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Subject: Geographic Information Systems FAQ
This article was archived around: 15 Apr 1997 16:44:19 -0400
(pretty hypertext version of this document)
Frequently Asked Questions and General Info List (Long! > 3200 lines)
Periodic Posting to GIS-L and comp.infosystems.gis
GIS FAQ List (97-03-13)
This is the list of frequently asked questions (FAQ) about Geographic
Information Systems (GIS) along with answers to these questions.* This
FAQ is posted as a resource to the `comp.infosystems.gis' newsgroup
which is connected to the GISL LISTSERVER mailing list.
1. How do I get the FAQ list?
2. What is the difference between the newsgroup and listserv?
3. Can I post a commercial advertisement to this list/group?
2. Research and Universities:
1. What in the world is a 'GIS'?
2. What colleges and universities offer coursework in GIS?
3. What are the NCGIA anon ftp sites and what can be found
4. Where is that On-Line GIS Bibliography (and what's in it)?
3. Data Formats and Map Products:
1. What are the United States map accuracy standards?
2. What is the Vector Product Format and where can I get
3. What is this SDTS thing and is it available via ftp?
4. What is a DXF file and where can I get info about it?
5. What is DEM and where can I find out about some?
6. Where can I get information about TIGER/Line? I heard there
is a terrific new and improved 1992 release...
7. How do I order USGS maps?
8. What is the Digital Chart of the World (DCW) and how do I get
9. Is there a package available to convert from UTM to
10. Does a file exists of latitude and longitude of US cities?
11. Where can I get old antique maps?
12. Is there a standard for representing latitude and longitude?
13. Has anyone compiled a list of standards and formats?
4. Other Sources of Information:
1. What are some other related mailing lists, ftp sites and
internet sources for useful resources?
2. Hey! But how do I subscribe to GIS-L, MAP-L, etc?
3. What are some books and magazines available on GIS?
4. Where can I get a copy of the SpatioTemporal Bibliography?
5. What professional organizations are out there for GISers?
6. What are some journal titles which carry GIS articles?
7. How can I subscribe to the Int'l Journal of GIS?
8. What are some World Wide Web URLs for GIS information?
9. Where can I find pointers to satellite data?
10. Are any mailing lists archived anywhere?
11. Can you recommend any other resource documents?
12. Can you point me towards some on-line job resources?
1. What are some algorithms for calculating the distance between
2. What is GPS?
3. What can you tell me about map projections?
6. Software Issues
1. What are e-mail and paper addresses of some vendors?
2. What public domain or shareware GIS software is available and
where is it?
3. Will GRASS run under LINUX OS on my PC?
4. How can I convert ARC files to IDRISI?
5. How can I convert ARC coverages to GRASS?
6. Where can I find some AMLs to look at?
7. How can I convert ARC files to some other graphics formats?
8. How do Arc/Info and Intergraph MGE compare?
If someone asks a FAQ, please e-mail the answer instead of posting.
You should also include information on how to access the FAQ. (see
If you have information that you think should be included in the FAQ,
please e-mail the information to Lisa Nyman <email@example.com>.
Feel free to discuss the information on the net to get a consensus
if the answer is canonical.
If you believe that some information in the FAQ is wrong, please e-mail
us. We don't want the FAQ to generate more postings than it saves! We
are not the authors of much of this information, only the compilers.
We will work with you and the author to resolve the issue. Credit is
given for contributing information gotten from the Net.
Avoid flamewars. When you get the urge to flame, wait until the urge
Q1.1: How do I get the FAQ list?
The most current version is available
via anonymous FTP on
Use your favorite WWW browser and take a peek at:
To get the FAQ in plain text (mail message > 100K), send a mail message to
Content doesn't matter (null message is ok).
If you wish to receive a gzip'ed and uuencoded version of the FAQ
(about 50% compression), specify 'gzip' or 'gzipped' (case doesn't matter,
only the first 4 characters are significant) on the 'Subject:'
line of the message.
Caveat: your mailer must supply a valid 'From:' return address.
To contribute to the FAQ, send mail to
Q1.2: What is the difference between the newsgroup and listserv?
The newsgroup comp.infosystems.gis is a Usenet special interest news
distribution scheme that allows individuals with access to Usenet to
read and post articles. The system is somewhat like e-mail but
involves a network of news 'feeds' that pass the news along.
The listserv system is a mailing list of e-mail addresses which allows
members to send messages to the GIS-L mailing list. The GIS-L mailing
list consists of a large number of people interested in GIS who receive
GIS related articles using their normal e-mail software.
Check with the systems administrator(s) at your site
to see if you receive USENET news or if a site mail alias has
already been set up for the mailing list before subscribing.
This will help cutdown on network traffic.
Articles sent to either of the above will be sent to the other so there
is no need to post to both groups.
[PLEASE NOTE: IF YOU READ GIS-L AND REPLY TO A MESSAGE, YOUR REPLY MAY
SENT TO THE ENTIRE LIST, NOT JUST THE ORIGINAL SENDER OF
THE LETTER. KNOW THY MAILER!]
A note to Usenet posters: To avoid the above problem, if you are
posting something like "Send me mail if you want a copy of..."
set the Followup-to: line in the post header to 'poster'.
Please use meaningful subject headings. For example, 'TIGER: How do I
determine boundaries?' is preferable to 'Duh! Need help'.
** Place job title and location in the subject line of job announcements.
It is important that people remember that messages to GIS-L end up on
Usenet and those with Usenet access should read new user information in
the news.announce.newusers group. One highlight to note is that while
product information can be valuable to a group, please post only one
article per product, as this should -not- become a commercial
advertisement center (See 1.3 below).
This is not a moderated group or list so sometimes irrelevant junk
gets posted. Please ignore such posts and let them dissappear.
Also, please keep .signatures to a reasonable number of lines.
Q1.3: Can I post a commercial advertisement to this list/group?
In principle, announcement of professional services or products on Usenet
newsgroups is allowed. Because GIS is still a relatively immature field,
resisting commercial postings on GIS-L may mean that genuinely useful
information, which is of interest to a majority of subscribers, is lost.
However,because commercialisation of the internet is racing forward, we must
have strict guidelines if GIS-L is to remain a useful discussion forum.
Therefore, for GIS-L, the following guidelines for COMMERCIAL postings will
(1) The product which is the subject of the announcement must be directly
related to GIS. This not the place to announce your new graphics package.
(2) Messages should be short (20 lines or one screen page) and should
reference any extended information through a user-request facility
(such as an email address, ftp, WWW etc.).
(3) The address used to post the message must be a valid, accessible internet
email address which individuals can REPLY to. The "Reply-to" address
header in the message must point to your personal email address - not to
GIS-L. Where you are posting to the newsgroup, make sure the "Follow-up"
header field is set to "poster" and NOT to "comp.infosystems.gis".
(4) Messages advertising a product must have an informational content greatly
in excess of their promotional content. Superlative adjectives should not
be used. Stick to technical facts.
(5) Messages of a purely advertising nature, as distinct from product
announcements should not be posted.
(6) An organisation should restrict themselves to occasional announcements
(no more than one per month). Messages should not be repeated unless they
contain new or updated information.
(7) The product must be of truly INTERNATIONAL interest. Announcements
relating to niche products or only of limited regional applicability are
not encouraged unless reflecting significant new or unique development
which is likely to be of genuine interest to GIS-L readers.
(8) It is good practice to assist readers by using informative subject fields,
for example "Advert:", "Product Announcement:" or simply "AD:" prefixing
a three or four word description of your message. Blank subject fields
should be avoided at all costs (personally I ignore all such messages).
Using a prefix and informative subject make it much more likely the people
you want to read your message will actually read it.
If you are not sure whether your proposed posting meets these guidelines
then DO NOT POST to GIS-L. There is an excellent alternative,
if you are using news, then full press releases, product announcements
and any promotional materials can be posted to the group "comp.newprod".
Where an individual regards that these guidelines have been broken they should
email the POSTER and tell them so. Please draw their attention to this entry
in the FAQ. A large amount of incoming email is a very effective means of
discouraging the poster from breaking the rules in the future. Please make
sure you email the POSTER and not THE LIST (check the reply address before you
use the reply function of your mailer. Failing to check this will result in
you receiving lots of email for GIS-L readers unhappy about your behaviour!
This policy may be subject to change in the light of new circumstances.
Thanks to Bruce gittings <BRUCE@geovax.ed.ac.uk>
Q2.1: What in the world is a 'GIS'?
From: Scott Freundschuh
What Is A Geographic Information System (GIS)?
An information system that is designed to work with data referenced by
spatial or geographic coordinates. In other words, a GIS is both a
database system with specific capabilities for spatially-referenced
data, as well as a set of operations for working [analysis] with the
data. (Star and Estes, 1990)
A system for capturing, storing, checking, integrating, manipulating,
analyzing and displaying data which are spatially referenced to the
Earth. (Chorley, 1987)
Automated systems for the capture, storage, retrieval, analysis, and
display of spatial data. (Clarke, 1990)
A system of hardware, software, and procedures designed to support the
capture, management, manipulation, analysis, modeling and display of
spatially-referenced data for solving complex planning and management
problems. (NCGIA lecture by David Cowen, 1989)
An integrated package for the input, storage, analysis, and output of
spatial information... analysis being the most significant. (Gaile and
GIS are simultaneously the telescope, the microscope, the computer, and
the xerox machine of regional analysis and synthesis of spatial data.
From: David Mark <firstname.lastname@example.org>
Can we come up with a definition of GIS that would provide a "truth in
advertizing" product defnition for what software can be advertized as being
a GIS, and what cannot,a definition which, when applied to all the packages
that we agree are GISs returns "TRUE", and for the others returns "FALSE".
From: email@example.com (Duane F Marble)
One of the distinctions is the ability to do overlay. Not draw two
things on top of each other, but the logical operation. The creation
of buffers via computation is also closely related. The distinction is
between mapping and analysis.
From time to time, theoretical discussions on this question pop-up.
Q2.2: What colleges and universities offer coursework in GIS?
Many schools throughout the world offer coursework in GIS and related
studies in different academic departments including Geography, Computer
Science, and Urban Planning among others.
Sources of Information:
1. Geo Info Systems May 1992, Academic GIS Directory: GIS in Higher
This is a list compiled by John Morgan with Barbara Fleury (Towson
State University) which includes courses offered by University
departments all over the world. Listing are by University,
department type, and by state and country. Information in the
listings include course titles, school addresses and persons to
2. Guides to Geography Departments, annual publication of the AAG.
[What does AAG mean? Association of American Geographers]
This publications provides graduate and undergraduate programs for
geography departments at US and Canadian Universities. Info
provided includes faculty, program options and requirements, and
Contact the AAG, 1710 16th Str NW, Washington DC 20009-3198 for
ordering information. AAG phone: 202-234-1450 Email: firstname.lastname@example.org
Note: Many faculty participate in Usenet and listserv discussions and
are directly accessible via Email.
Q2.3: What are the NCGIA anon ftp sites and what can be found there?
From: Karen Kemp <kemp@ncgia.UCSB.EDU>
The National Center for Geographic Information and Analysis (NCGIA) has a
publicly available ftp site as well as a WWW homepage which points at the
If the Santa Barbara site is unavailable, this site is mirrored at the
other two NCGIA centers:
University of Maine: grouse.umesve.maine.edu in the pub/NCGIA/UCSB directory
SUNY Buffalo: ncgia.geog.buffalo.edu
As of January 1995, about 30% of the pre-1995 technical report series are
available through ftp. New reports will be added as the digital files
become available. To see the full list of NCGIA technical reports, view
the file "pub_list" available both at the root directory of our ftp site
and inside the pub directory.
To access the files in this site, ftp to "ftp.ncgia.ucsb.edu" as the user
"anonymous" with any password, and "cd" into the "pub/Publications"
directory. Here there are several directories:
annual_reports - NCGIA annual reports
biblio - GIS bibliographies
final_reports - final reports on closed research initiatives
pubs_list - ASCII version of the current publication list
tech_reports - reports from the NCGIA Technical Report series
These directories have subdirectories by year and within those are
subdirectories by document. Within each of the document subdirectories you
will usually find "text" and "postscript" versions. In some cases there
are also other digital formats, data files and readme files.
Q2.4: Where is that On_Line GIS bibliography (and what's in it)?
From: Duane F. Marble <email@example.com>
GIS MASTER BIBLIOGRAPHY PROJECT
Department of Geography
The Ohio State University
Columbus, Ohio 43210
The first update components of the GIS Master Bibliography are
now available on-line. All entries contain a full abstract (used
with permission of the copyright holder) and are available in two
REFER - a standard ASCII file utilizing standard codes (e.g.,
%A) which permit use of the file with software available
on most UNIX systems or it may be searched in most word
ENDNOTE - a binary library file configured for the commercial
EndNote and EndNote Plus software (available for either
the PC or the Mac). EndNote permits citation formatting
for a variety of journals, automatic addition of refer-
ences to papers, etc.
Please feel free to copy and make use of this bibliographic
material in your own research and development activities. Please do
NOT redistribute all or even part of the bibliography without
written permission from the publisher since reproduction of the
abstracted material is governed by standard international copyright
We wish to acknowledge the generous support of ESRI which has
contributed significantly to the start-up of this activity.
There are several ASCII files located in the /ftp/biblio area.
(A) A complete description of the Master Bibliography
(B) A time-stamped list of the materials currently available.
(C) A list of contact addresses for the publishers of the
materials in the various bibliographic files.
International Journal of Geographical Information Systems
All issues from inception of publication thru 1992 - one file
containing 177,510 bytes (REFER) or 199,168 bytes (PC
Current (1993) issues: each issue is in a separate file with
the first issue of 1993 designated as IJGIS_A.REF or
IJGIS_A.LIB, the second as IJGIS_B, etc. There will be at
total of six issues in 1993.
International Journal of Remote Sensing
Selected articles relating to GIS starting with 1993: each
issue (one or more articles) is in a separate file with
the first issue of 1993 designated as IJRS_A.REF or
IJRS_A.LIB, the second as IJRS_B, etc. NOTE: not all
issues contain GIS-related articles!
International Symposia on Spatial Data Handling (IGU Commission on
1984 thru 1992 (First thru Fifth Symposia) - separate files
1984 - 40,861 bytes (REFER) or 60,928 bytes (PC EndNote)
1986 - 56,325 bytes (REFER) or 73,728 bytes (PC EndNote)
1988 - 33,556 bytes (REFER) or 53,248 bytes (PC EndNote)
1990 - 116,554 bytes (REFER) or 155,136 bytes (PC End-
1992- 84,661 bytes (REFER) or 105,472 bytes (PC EndNote)
Urban & Regional Information Systems Association
1992 Annual Conference Proceedings: one file containing
126,260 bytes (REFER) or 165,888 bytes (PC EndNote)
1993 Annual Conference Proceedings: one file containing 72,853
bytes (REFER) or 99,840 bytes (PC EndNote)
Obtaining Copies of Current Files via Anonymous FTP
Access to current files is available via anonymous FTP for
those individuals and organizations having access to the Internet.
Because of copyright restrictions, files will be restricted to
those instances where formal agreements have been signed with the
To access the currently available files enter the following
ftp 188.8.131.52 (this is BASTET@SBS.OHIO-STATE.EDU)
when you are asked to log in, respond with the user name of
when you are asked for a password, please respond with your
When the log on operation is completed, change to the
appropriate directory by using one of the following commands:
cd biblio (this places you in the base direc-
tory for the project -- several
ASCII information files are located
cd /biblio/gis.refer (this places you in a directory with
files in REFER (ASCII) format)
cd /biblio/gis.pc (this places you in a directory with
files in EndNote format for the PC)
NOTE: Mac versions of the EndNote libraries will be available
cd /biblio/gis.mac (this places you in a directory with
files in EndNote format for the Mac)
You may now copy any of the available files. For example, to
copy the ASCII bibliographic entries for the 1992 Spatial Data
Handling Symposium select the gis.refer directory and issue the
command: get sdh92.refer
FTP also supports the command mget which permits the retrieval of
multiple files using wild card specifications. For example to
retrieve all of the ASCII files dealing with the various Spatial
Data Handling Symposia, select the gis.refer directory and issue
the command: mget sdh*.*
If you are planning to copy either the PC or Mac versions of the
EndNote binary files, you must issue the following command before
issuing the command to get a copy of the desired file- binary
After the file(s) have been copied, they should reside in your
default directory on your home machine. To leave the FTP session,
issue the final command: quit
The master bibliography is searchable at the URL
Q3.1: What are the United States map accuracy standards?
From: rcw@scicom.AlphaCDC.COM (Robert White)
United States National Map Accuracy Standards
With a view to the utmost economy and expedition in producing maps
which fulfill not only the broad needs for standard or principal maps,
but also the reasonable particular needs of individual agencies,
standards of accuracy for published maps are defined as follows:
1. Horizontal Accuracy. For maps on publication scales larger than
1:20,000, not more than 10 percent of the points tested shall be in
error by more than 1/30 inch, measured on the publication scale; for
maps on publication scales of 1:20,000 or smaller, 1/50 inch. These
limits of accuracy shall apply in all cases to positions of well-
defined points only. Well-defined points are those that are easily
visible or recoverable on the ground, such as the following:
monuments or markers, such as bench marks, property boundary
monuments, intersections of roads, railroads, etc.; corners of large
buildings or structures (or center points of small buildings); etc.
In general what is well defined will also be determined by what is
plottable on the scale of the map with 1/100 inch. Thus while the
intersection of two road or property lines meeting at right angles
would come within a sensible interpretation, identification of the
intersection of such lines meeting at an acute angle would obviously
not be practicable within 1/100 inch. Similarly, features not
identifiable upon the ground within close limits are not to be
considered as test points within the limits quoted, even though
their positions may be scaled closely upon the map. In this class
would come timber lines, soil boundaries, etc.
2. Vertical Accuracy, as applied to contour maps on all publication
scales, shall be such that not more than 10 percent of the
elevations tested shall be in error more than one-half the contour
interval. In checking elevations taken from the map, the apparent
vertical error may be decreased by assuming a horizontal
displacement within the permissible horizontal error for a map of
3. The accuracy of any map may be tested by comparing the positions of
points whose locations or elevations are shown upon it with
corresponding positions as determined by surveys of a higher
accuracy. Tests shall be made by the producing agency, which shall
also determine which of its maps are to be tested, and the extent of
4. Published maps meeting these accuracy requirements shall note this
fact on their legends, as follows: "This map complies with National
Map Accuracy Standards."
5. Published maps whose errors exceed those afore stated shall omit from
their legends all mention of standard accuracy.
6. When a published map is a considerable enlargement of a map drawing
(manuscript) or of a published map, that fact shall be stated in the
legend. For example, "This map is an enlargement of a
1:20,000-scale map drawing," or "This map is an enlargement of a
1:24,000-scale published map."
7. To facilitate ready interchange and use of basic information for map
construction among all federal map making agencies, manuscript maps
and published maps, wherever economically feasible and consistent
with the uses to which the map is to be put, shall conform to
latitude and longitude boundaries, being 15 minutes of latitude and
longitude, or 7.5 minutes or 3-3/4 minutes in size.
US Bureau of the Budget
Issued June 10, 1941
Revised April 26, 1943
Revised June 17, 1947
Q3.2: What is the Vector Product Format and where can I get information?
From: firstname.lastname@example.org (Thomas Misek)
The document that lists the format & form of the Vector Product Format
30 September 1993
This 200+ page document has a complete description of the format.
[old address deleted - new address from email@example.com (Donald
The correct address for the public to request any MIL-STD is:
Naval Publications & Forms Center
5801 Tabot Ave.
Philadelphia, PA 19120
Phone: (215) 697-2000
This is DoD's central supply house for MIL-STDs. They are, by the way,
all free to US addresses.
[original article continues]
Since the VPF has been created as a means for transmitting digital
geographic databases, I, for one, would be interested in any programs
that make use of the format.
Q3.3: What is this SDTS thing and is it available via ftp?
From: "Dan Henke" <firstname.lastname@example.org>
Spatial Data Transfer Standard (SDTS) is a standard which by definition is " a
document that specifies a set of rules". The SDTS provides a way of
the transfer of digital spatial data between dissimilar computer systems. It
also preserves the information meaning and minimizes the need for any external
information. This standard not only allows the transfer of spatial data,
attributes and georeferencing but also the data quality report, data dictionary
and any other associated metadata.
Promoting and facilitating the transfer of spatial data between dissimilar
computer systems provides users and producers of spatial data with a way to
gain access to a greater amount of otherwise inaccessable data. It also
promotes data exchange and data sharing, which in turn increase the quality and
the integrity of existing spatial data.
SDTS is designed to support all types of spatial data. A single translator that
could support all the different types and options of data is probably not
practical. It is much better to implement SDTS through the use of profiles. A
profile is a subset of SDTS which was created to transfer a specific type of
spatial data with as few SDTS options as possible. The Topological Vector
Profile (TVP) was the first developed and applies to geographic vector data
with planar graph topology. This profile will handle both USGS DLG-3 and DLG-F
data as well as the Census Bureau's TIGER data. The Raster Profile was
developed to accomodate image data, digital terrain models,gridded GIS layers,
and other gridded data. This profile will accomodate USGS DEM's and DOQ's.
SDTS was approved as Federal Information Processing Standard (FIPS) Publication
173 in 1992 after 12 years of development and testing and in 1994 became
mandatory for federal agencies. SDTS is available for use also by state and
local goverments, the private sector and research and academic organizations.
SDTS information including the Standard itself and much more is available via
More information on SDTS is also available by visiting the SDTS web page
You may also write :
SDTS Task Force
U. S. Geological Survey
1400 Independence Road
Rolla, MO. 65401
or Call 573/308-3543, FAX 573/308-3652
or e-mail : email@example.com
Q3.4: What is a DXF file and where can I get info about it?
From: tchild@AUTODESK.COM (Timothy Child)
DXF(R) is the Drawing eXchange Format from AutoCAD. The definitive
documentation for this format is in the current AutoCAD Release 12
Customization Manual. I believe that a copy of the DXF appendix is also
posted on the Autodesk Compuserve forum. Try contacting the Autodesk
Australian office for details on this:
9 Clifton St.
P.O. Box 458
Another good reference for the DXF format is provided in:
The AutoCAD Database Book
Authors: F.H. Jones and L. Martin
Published by Ventana Press
Ventana Press may be contacted at:
P.O. Box 2468
Phone (919) 490-0062
Also, Virginia Hetrick, in sunny Calififornia <IARGRAF@MVS.OAC.UCLA.EDU>
Kay, David C., and John R. Levine (1992) Graphics File Formats.
Sorry, I don't know either the ISBN number or the publisher since
I just got an ad with the book identified in it and it specifically
says that it contains a description of DXF formats. I'd suspect
that this one is probably more readily available in libraries than
A page of links:
Release 13 documentation in Windows Help format
with a supplementary browser to simplify searching:
Release 10 documentation in text format:
Q3.5: What is DEM?
From: David Mark (firstname.lastname@example.org)
The terminology in this area is somewhat complicated. The U.S.
Geological Survey does indeed have a 'product' that is called "Digital
Elevation Model". These are gridded elevation data, 30 m resolution.
Standard data sets cover 7.5 minute by 7.5 minute areas equivalent to
USGS 1:24,000 scale maps. The USGS has another data-set series called
"Digital Terrain Models", most or all of which were originally
developed by the US Army and/or Defense Mapping agency, from 1:250,000
Outside of USGS, there is some disagrement in the literature as to
whether "Digital Elevation Model" (DEM) is a _generic_ term for all
digital data for elevations, including TINs, digitized contours, etc.,
or whether the DEM term should be restricted to regular rectangular
grids. Those who prefer to restrict the term DEM to grids often prefer
to use "Digital Terrain Model" (DTM) as the _generic_ term for all
computerized elevation data.
Bruce Gittings maintains a Digital Elevation Data catalogue, which is posted
monthly on GIS-L. This catalogue, which is regularly updated, contains
descriptions of a large number of topographic and bathymetric datasets with
local, regional and global extent. There are also useful references to a
number of other types of data (eg. USGS products, Digital Chart of the World,
regional databases for Asia, Europe etc.). It is well worth checking this list
before looking elsewhere for data.
The most up-to-date version of this catalogue is available through the
Edinburgh GIS WWW server.
The catalogue is also available through a mail server. Send e-mail to
email@example.com for full details of how to use this service.
DEMs are available from spectrum.xerox.com [184.108.40.206], /pub/map
Lee Moore -- Webster Research Center, Xerox Corp.
Voice: +1 (716) 422 2496
Arpa, Internet: Moore.Wbst128@Xerox.Com
For information on converting DEM to ARCVIEW format, see
Q3.6: Where can I get information about TIGER/Line? I heard there is a terrific new and improved release... :-)
For information on TIGER/Line products and releases,
call the US Census Bureau at 301-457-4100
Call particular vendors for TIGER to vendor-format conversion problems.
Also, get TIGER information on the WWW at:
And while we're on the subject of Census Data....
From: Henk Meij <firstname.lastname@example.org>
A data archive was created and is maintained by the National
Aeronautics and Space Administration (NASA), under GSFC Letter
Contract NAS5-32632, by the Socioeconomic Data and Applications
Center (SEDAC) of the Consortium for International Earth Science
Information Network (CIESIN) in cooperation with the Urban Information
Center (UIC) at the University of Missouri St. Louis.
The archive contains boundary files based on 1992 TIGER/Line, standard
extract files based on 1990 STF3A, Block statistics from STF1B,
and enhanced migration files based
on STP28, county to county. This is alla vailable at:
<login in as "ftp" or "anonymous">
<send email address as password>
o helpful readme files will be displayed to the screen
o documentation, albeit still sparse, online
o all files in (binary) zipped archive-file format
(use ftp mode BINARY for retrieval)
o unzip binaries for many platforms provided as well as
unzip/zip source code
Q3.7: How do I order USGS maps?
It's easy. Just call (in the US) 1-800-USA-MAPS
Q3.8: What is the Digital Chart of the World (DCW) and how do I get one?
From: Mike Phoenix <esri!mailgate_esri!mike_phoenix@UUNET.UU.NET>
The Digital Chart of the World is a 1.7 GB digital geographic database
that is available on CD-ROM. It was input from 1:1,000,000 Operational
Navigation Charts and 1:2,000,000 Joint Navigation Charts. It includes
17 layers, aeronautical info, data quality info, drainage, supplemental
drainage, hypsography, hypsography supplemental, land cover, ocean
features, physiography, political/ocean, populated places, railroads,
transportation structure, utilities, and vegetation.
It is ISO9660 compatible and only $200.00. It is available from:
For civilian customers only (military users have a different set of
contacts in each of the four regions). In the US, Latin America, Asia,
U.S. Geological Survey
ESIC-Open File Section
Mail Stop 517
Denver, CO 80225, USA
Tel. (303) 202-4200 <-- new number
Products and Services Division
Surveys, Mapping, and Remote Sensing Sector
Energy, Mines and Resources Canada
615 Booth Street, Room 400
Ottawa, Ontario, CANADA K1A 0E4
Tel. (613) 995-2123
Fax. (613) 995-6001
Cambridge CB2 INR
Tel. (0223) 311479
Fax. (0223) 66440
AUSMAP Data Unit
P.O. Box 2
BELCONNEN ACT 2617
Sindre Langaas <SINDRE@system.ecology.su.se> has more info at
From: email@example.com (Karl A. Nyberg)
Payment (check, money order, purchase order, or Government account)
must accompany order. Make all drafts payable to the Department of the
Interior -- U. S. Geological Survey.
The DCW package can also be purchased over-the-counter from any Earth
Science Information Center [ESIC] by check, money order, purchase
order, Government account, credit card, or cash. Missing or defective
material will be replaced free if reported to the office that took the
order, by telephone or in writing, within 90 days of purchase.
Cost $200 per package.
Includes 4 CD ROMs, 3 5.25 and 3.5 floppies containing various source
and executable files for VPFVIEW, a program for displaying the data on
You need DOS 3.1 or higher, CD-ROM Extensions 2.0 or higher. 8086
with 8087, VGA or EGA and arrow key, mouse, 30MB hard drive with at
least 20 percent free 1MB RAM, CD ROM drive.
I was told that the FASTEST way was to order it from Denver. I sent in
my check on 8/21 and received the package today from UPS.
I believe that DoD components can order directly from DMA, although I
don't know how. That information is probably classified, and I don't
have either a clearance OR a need to know. :-)
There's apparently also a version of VPFVIEW in process for the Sun
SPARC, with public availability estimated to be within the next couple
months. (That's what I'm looking forward to!)
The DCW is also available as an Arc/Info coverage.
for more info.
Q3.9 Is there a package available to convert FROM UTM to latitude/longitude?
An on-line service is available at:
The Geographic Calculator
Resolution Mapping, Inc., River Road, P.O. Box 718, Newcastle, ME
04553. (207) 563-2311. The GC is a Microsoft Windows application that
enables conversion to-from Lat/Long, State Plane, UTM, Landsat WRS,
user defined coordinate and other systems. It sells for $225. This is
a solution if you don't have something like Arc/Info, in which these
CONVERTsions are standard fare.
Terra Data, Inc (Bramblebush,
Croton-on-Hudson, NY 10520) (212 675-2971).
it does map projections; Mac based; $499.
PROJ is a standard Unix filter function which converts geographic longitude
and latitude coordinates into cartesian coordinates, (lambda,phi) -> (x,y),
by means of a wide variety of cartographic projection functions. For many
of the projection functions the inverse conversion, (x,y) -> (lambda,phi),
can also be performed."
The Unix version of the software (buildable with gcc) and
PC-DOS version of the software (both executable & source) are located in
This software supports a *very* robust set of coordinate projection systems,
datums, and ellipsoids. This software is especially useful if you have to
convert large batches of coordinates.
GeoConverter ($5.00 shareware)
This software does accurate conversions between
UTM and Long/Lat for Macintosh computers.
Q3.10: Does a file exists of latitude and longitude of US cities?
From: Craig Best <firstname.lastname@example.org>
Yes, the Census Bureau has such a beast at
This is a self-extracting file containing 51 dbf files,
one for each state and DC.
Q3.11: Where can I get old antique maps?
Contact the International Map Dealers Association.
Norman Strasma is the Executive V.P., and their offices are in
Kankakee, Il (PO Box 1789, Zip=60901-1789, phone 815-939-4627)
Library of Congress
Also, try local libraries [Ed. note: I got a *great* map of
Buffalo from 1854 at the Erie County Public Library. It's an old
insurance map with building types denoted.].
Q3.12: Is there a standard for representing latitude and longitude?
Yes. ISO 6709:1983 Standard Representation of Latitude, Longitude and
Altitude for Geographic Point Locations.
Q3.13: Has anyone compiled a list of standards and formats?
Yes, people are attempting to do this. For a start, check out:
Q4.1: What are some other related mailing lists, ftp sites and internet sources for useful resources?
A. Bill Thoen has compiled a *huge* resource list titled
"On-line Resources Earth Sciences". This list is very detailed
and well organized. It is a valuable addition to any
library and is available at:
Also, see Bill's articles in the Feb and August 1994 GIS World.
Q4.2: How do I subscribe to GIS-L?
If you are unable to access the comp.infosystems.gis newsgroup,
you can see the same discussion by subscribing to GIS-L.
Send the one line message: subscribe GIS-L <your_name>
Items to be distributed to the list should be sent to
GIS-L@URISA.ORG or posted to comp.infosystems.gis.
To Subscribe to ESRI-L: Send message to: "email@example.com".
In the subject line of the message, type the word: "subscribe"
To Unsubscribe from ESRI-L: Send message to: "firstname.lastname@example.org".
In the subject line of the message, type the word: "unsubscribe"
To subscribe to ai-geostats, send the following in the body (not
the subject line) of an email message to "Majordomo@gis.psu.edu":
This will subscribe the account from which you send the message to
the ai-geostats list.
ai-geostats-digest also exists. Send mail to
email@example.com to get the info.
Q4.3: What are some books and magazines available on GIS?
____ GeoInfo Systems Magazine, PO Box 7678, Riverton, NJ 08077-9178
$59/year. Email: firstname.lastname@example.org
____ GIS World and Business Geographics magazines, and the 199x GIS
Sourcebook, all from GIS World Inc, 155 E Boardwalk Drive,
Suite 250, Fort Collins, CO 80525. Email: email@example.com
____ Proceedings: 5th International Symposium on Spatial $50.00
Data Handling. IGU Commission on GIS, August 1992,
Charleston, South Carolina.
Two volume set contains more than seventy selected papers
representing the state of the art in geographical information
____ Time in Geographic Information Systems, by Gail Langran. $40.00
Taylor & Francis, 1992.
Thorough examination of the conceptual, logical, and physical
design of temporal GISs. This book reviews the literature;
discusses implementation issues such as clustering, quality
control, and volume control; and introduces original and
previously unpublished research on the extension of existing
spatial data structuring techniques to a three-dimensional
____ Accuracy of Spatial Databases, edited by Michael Goodchild. $77.00
Taylor & Francis, 1989.
Detailed treatment of error and accuracy, particularly of
modelling uncertainty and reliability, testing accuracy, and
the practical implications for use of spatial data.
____ An Album of Map Projections, U.S.G.S. Professional Paper 1453,
John Snyder and Philip Voxland, 1989.
____ Analytical and Computer Cartography, by Keith Clarke. $52.00
Prentice Hall, 1990.
____ Applications of Spatial Data Structures, by Hanan Samet. $45.25
Applications of hierarchical data structures in computer
graphics,image processing, and GIS.
____ Building Databases for Global Science, edited by Helen $93.00
Mounsey. General Editor: Roger Tomlinson.
Taylor & Francis, 1988.
Papers from the first meeting of the International
Geographical Union's Global Database Planning Project.
____ Design and Analysis of Spatial Data Structures, by $43.25
Hanan Samet. Addison-Wesley, 1990.
Hierarchical (quadtree and octree) data structures.
____ Fundamentals of Geographic Information Systems: A $60.00
Compendium. ACSM, 1990.
____ Fundamentals of Spatial Information Systems $49.95
Robert Laurini and Derek Thompson
Academic Press, London, UK 1992, 700 pages approx.,
ISBN 0-12-438380-7. (Particularly nice illustartions ;-))
____ Geographic and Land Information Systems for $45.00
Practicing Surveyors: a Compendium. ACSM, 1991.
____ Geographic Information Systems: A Management $57.00
Perspective, by Stan Aronoff. WDL Publications, 1989.
An excellent introduction to GIS principles and applications
for users and managers.
____ Geographic Information Systems: An Introduction, by $51.00
Jeffrey Star and John Estes. Prentice Hall, 1990.
Introductory textbook for students and professionals.
____ Geographic Information Systems and Cartographic $51.00
Modelling, by Dana Tomlin. Prentice Hall, 1990.
Introduction to cartographic modelling, emphasizing
environmental decisions, that develops a high-level
cartographic computing language.
____ Geographic Information Systems for Resource $60.00
Management, edited by William Ripple. ACSM, 1986.
Papers on land suitability; water, soil, and vegetation
resource management; and urban and global GIS applications.
____ Geographical Information Systems: Principles and $295.00
Applications, edited by David J. Maguire, Michael
F. Goodchild and David W. Rhind. John Wiley & Sons, 1991.
Two-volume boxed set contains sixty new papers; the most
ambitious, extensive, and authoritative GIS book to date.
____ The Geography Coloring Book, by Wynn Kapit $10.00
Harper Collins, 1991.
A creative and expert study aid for learning geography.
Contains coloring plates and index.
____ The Global Positioning System and GIS, by Michael Kennedy
An educational tool intended as an introduction for all mapping science
professionals, managers, and students. For use in the classroom, or
as a self-teaching guidebook, "GPS and GIS" explains how GPS works,
examines software and hardware options, and provides theory to
application in a manual. Ann Arbor Press ISBN 1-57504-017-4
____ Handbook of Relational Database Design, by Candace $46.00
Fleming and Barbara von Halle. Addison-Wesley, 1989.
This book provides a practical approach to designing relational
databases. It contains two complementary design methodologies: logical
data modeling and relational database design. The methodologies are
independent of product-specific implementations and have been applied
to numerous relational product environments.
____ (workbook). UGC Corporation, 1990.
Management-level primer on GIS with accompanying video.
[Ed. note: at one time this was offered without the video free
____ How to Choose A GIS Consultant, available free from
EI Technologies, LLC, 2620 S. Parker Road, Ste. 150,
Aurora, CO 80014.
____ Interpreting Space: GIS and Archaeology, edited by $79.00
Kathleen M. S. Allen, Stanton W. Green and Ezra B. W.
Zubrow. Taylor & Francis, 1990.
The first book to address the use of GIS in archaeology and
____ Introduction to Database Systems, Vol I, by C. J. Date. $46.25
Fifth edition. Addison-Wesley, 1990.
____ Introduction to Database Systems, Vol II, by C. J. Date. $45.25
____ Introduction to Urban GIS, by William Huxhold (paper). $32.50
Oxford University Press, 1991.
____ Introductory Readings in Geographic Information $39.00
Systems, edited by Donna Pequet and Duane Marble.
(paper). Taylor & Francis, 1990.
Selection of articles on various aspects of GIS.
____ Map Appreciation, by Mark Monmonier. $41.00
Prentice Hall, 1988.
Teaches how to work with maps and promotes graphic literacy.
____ Map Generalization: Making Rules for Knowledge $95.00
Representation, edited by Barbara Buttenfield and Robert
John Wiley & Sons, 1991.
This book is the first to focus on the development of a rule
base for digital mapping. It identifies the problems involved
in the development of a rule base for digital maps used in
GIS, and it provides a framework to help solve these problems,
improve efficiency, preserve consistency, and incorporate
sound principles into digital mapping.
____ Mapping the Next Millenium: The Discovery of New $30.00
Geographies, by Stephen Hall
Random House, 1992.
Contains reports from the scientific frontiers where virtually
every aspect of the physical cosmos is being mapped, including
the floor of the ocean, the hole in the ozone layer, the
interior of the earth, atoms and chromosomes, the farthest
planets of the solar system, the large-scale structure of the
universe, and even the mathematical construct known as pi.
_____ Map Projections---A Working Manual. USGS Professional Paper 1395.
by John Snyder. $32. Available from USGS Distribution Center, Box
25286, MS 306, Denver Federal Center, Denver, CO 80225.
____ Principles of Geographical Information Systems for $44.00
Land Resources Assessment, by P. A. Burrough.
Oxford University Press, 1986.
Textbook for more advanced GIS specialists.
____ Reactive Data Structures for Geographic Information Systems,
Peter van Oosterom 1994
Oxford University Press, ISBN 0-19-823320-5.
This 200-page book is part of the "Spatial Information Systems" series
of Oxford University Press (General Editors: P.H.T. Beckett,P.A. Burrough,
M.F. Goodchild, and P. Switzer). The full price of the book is 25 pounds.
In addition to an overview of GIS-technology this book contains many
recent research results. This is illustrated with many figures (80) and
references (296) and easy accessible by an index with 872 entries.
____ Statistics for Spatial Data, by Noel Cressie. $90.00
John Wiley & Sons, 1991.
The most comprehensive and readable text to date on the
analysis of spatial data through statistical models. It
unifies a previously disparate subject under a common approach
____ Three Dimensional Applications in Geographic Information $66.00
Systems, edited by Jonathan Raper.
Taylor & Francis, 1989.
Survey of approaches and problems in modelling real
Q4.4: Where can I get a copy of the SpatioTemporal Bibliography?
From: soo@CS.ARIZONA.EDU (Michael Soo)
If you would like a copy of the document or the database and do not
have ftp access, we ask that you first try the ftpmail facility
available on cs.arizona.edu. Simply send an e-mail message to
firstname.lastname@example.org that contains the ftp commands needed to
retrieve the desired files. The subject line of the message is
For example, to retrieve both the postscript bibliography and the
bibliographic database, the body of the message should contain the
The files will be mailed back to you, divided into chunks that can be
glued together with the help of your favorite editor.
Q4.5: What are some professional organizations out there for GISers?
URISA is the Urban and Regional Information Systems Assn
900 Second St. NE, Ste 304
Washington, DC 20002
(202) 289-1685 Email: email@example.com
URISA is a large organization of primarily governmental interest folks
that use information systems in general, and it has a large element of
GIS interests included in that. They hold a large national conference,
publish a journal, and distribute periodic newsletters, including one
devoted exclusively to GIS job listings (URISA Marketplace).
14456 E. Evans Ave
Aurora, CO 80014
AM/FM-I is another fairly large organization that deals largely with
GIS applications in facilities management and utilities-related mapping.
It also hosts an annual conference, publishes a newsletter, and provides
educational support through scholarships and internships.
---Martin D. Crossland
Computer Information Systems Dept
AAG is the Association of American Geographers, the address is
1710 Sixteenth St NW, Washington, DC 20009-3198 USA.
Voice (202) 234-1450, FAX: (202) 234-2744
E-Mail: firstname.lastname@example.org. Membership: email@example.com
Q4.6: What are some journals which carry GIS articles?
From: Casson Stallings and Friends <firstname.lastname@example.org>
Annals of the Association of American Geographers
Business Geographics (business)
Cartography and GIS
Computer (algorithms and visualization)
Computers, Environment, and Urban Systems
Computers and Geoscience
IEEE Trans. on Comp. Graphics and Applications (visualizaiton)
International Journal of GIS
Photogrammetric Engineering and Remote Sensing
Journals that carry some GIS articles:
International Journal of Remote Sensing
Remote Sensing Review
Q4.7: How can I subscribe to the Int'l Journal of GIS?
From: Duane F. Marble <email@example.com>
Dr. Peter F. Fisher
Midlands Regional Research Laboratory
Department of Geography
University of Leicester
Leicester, LE1 7RH
North American Editor:
Dr. Keith Clarke
Department of Geology and Geography
City University of New York
695 Park Avenue
New York, NY 10021
Online or Print Version (GISO):
Personal: US$239 (print only)
Online and Print Version (GISOP):
United States, Canada, and Mexico Subscriptions:
Taylor & Francis, Inc.
1900 Frost Road, Suite 101
Bristol, PA 19007
R. Hill & Son Ltd.
119 Gardenvale Road, Suite 2
Gardenvale, Victoria 3185
New Zealand Subscriptions:
R. Hill & Son Ltd.
Universal Subscription Agency Pvt. Ltd.
101-102 Community Centre
Malviya Nagar Extn
Post Bag No. 8
New Delhi 110017
Kinokuniya Company Ltd.
P.O. Box 55
Q4.8: What are some World Wide Web URLs for GIS information?
[Ed. Note 2/13/97: It's a waste of space to keep a list of URLs
here so from now on I'll only list a few good jump sites.]
Yahoo! GIS Page
Jim Aylward's Great GIS Net Sites
Paul Leunissen's GIS*Links
Q4.9 Where can I find pointers to satellite data?
One site is SOEST SATELLITE OCEANOGRAPHY LABORATORY:
Q4.10: Are any mailing lists archived anywhere?
ESRI-L, ARCVIEW-L and IMAGRS-L are archives at:
To Get ESRI-L Archives: For a list of all the ESRI-L archive server commands,
send a message with "archive" in the subject line and "help" in the body
to "firstname.lastname@example.org". You will receive a document that explains how
to search and retrieve the ESRI-L archives.
ai-geostats is archives at:
Q4.11: Can you recommend any other resource documents?
The Virtual Earth - A Tour of the WWW for Earth Scientists
Q4.12: Can you point me towards some on-line job resources?
Sure we can. Use your favorite WWW browser to access:
The GIS Jobs Clearinghouse
The Geosci Jobs Archive
Q5.1: What is the best way to calculate the great circle distance (which deliberately ignores elevation differences) between 2 points?
(This answer was prepared by Robert G. Chamberlain of Caltech (JPL):
email@example.com and reviewed on the comp.infosystems.gis
newsgroup in Oct 1996.)
If the distance is less than about 20 km (12 mi) and the locations of the
two points in Cartesian coordinates are X1,Y1 and X2,Y2 then the
d = sqrt((X2 - X1)^2 + (Y2 - Y1)^2)
will result in an error of
less than 30 meters (100 ft) for latitudes less than 70 degrees
less than 20 meters ( 66 ft) for latitudes less than 50 degrees
less than 9 meters ( 30 ft) for latitudes less than 30 degrees
(These error statements reflect both the convergence of
the meridians and the curvature of the parallels.)
The flat-Earth distance d will be expressed in the same units as
If the locations are not already in Cartesian coordinates, the
computational cost of converting from spherical coordinates and
then using the flat-Earth model may exceed that of using the
more accurate spherical model.
Otherwise, presuming a spherical Earth with radius R (see below), and the
locations of the two points in spherical coordinates (longitude and
latitude) are lon1,lat1 and lon2,lat2 then the
Haversine Formula (from R.W. Sinnott, "Virtues of the Haversine",
Sky and Telescope, vol. 68, no. 2, 1984, p. 159):
dlon = lon2 - lon1
dlat = lat2 - lat1
a = sin^2(dlat/2) + cos(lat1) * cos(lat2) * sin^2(dlon/2)
c = 2 * arcsin(min(1,sqrt(a)))
d = R * c
will give mathematically and computationally exact results. The
intermediate result c is the great circle distance in radians.
The great circle distance d will be in the same units as R.
The min() function protects against possible roundoff errors that
could sabotage computation of the arcsine if the two points are
very nearly antipodal (that is, on opposide sides of the Earth).
Under these conditions, the Haversine Formula is ill-conditioned
(see the discussion below), but the error, perhaps as large as
2 km (1 mi), is in the context of a distance near 20,000 km
Most computers require the arguments of trignometric functions to
be expressed in radians. To convert lon1,lat1 and lon2,lat2 from
degrees, minutes, and seconds to radians, first convert them to
decimal degrees. To convert decimal degrees to radians, multiply
the number of degrees by pi/180 = 0.017453293 radians/degree.
Inverse trigonometric functions return results expressed in
radians. To express c in decimal degrees, multiply the number of
radians by 180/pi = 57.295780 degrees/radian. (But be sure to
multiply the number of RADIANS by R to get d.)
The problem of determining the great circle distance on a sphere
has been around for hundreds of years, as have both the Law of
Cosines solution (given below but not recommended) and the
Haversine Formula. Sinnott gets the credit here because he was
quoted by Snyder (cited below). Perhaps someone will provide the
truly seminal reference so the proper attribution can be given?
The Pythagorean flat-Earth approximation assumes that meridians are
parallel, that the parallels of latitude are negligibly different from
great circles, and that great circles are negligibly different from
straight lines. Close to the poles, the parallels of latitude are not only
shorter than great circles, but indispensably curved. Taking this into
account leads to the use of polar coordinates and the planar law of cosines
for computing short distances near the poles: The
Polar Coordinate Flat-Earth Formula
a = pi/2 - lat1
b = pi/2 - lat2
c = sqrt(a^2 + b^2 - 2 * a * b * cos(lon2 - lon1)
d = R * c
will give smaller maximum errors than the Pythagorean Theorem for
higher latitudes and greater distances. (The maximum errors, which
depend upon azimuth in addition to separation distance, are equal
at 80 degrees latitude when the separation is 33 km (20 mi),
82 degrees at 18 km (11 mi), 84 degrees at 9 km (5.4 mi).) But
even at 88 degrees the polar error can be as large as 20 meters
(66 ft) when the distance between the points is 20 km (12 mi).
The latitudes lat1 and lat2 must be expressed in radians (see
above); pi/2 = 1.5707963. Again, the intermediate result c is the
distance in radians and the distance d is in the same units as R.
An UNRELIABLE way to calculate distance on a spherical Earth is the
Law of Cosines for Spherical Trigonometry
** NOT RECOMMENDED **
a = sin(lat1) * sin(lat2)
b = cos(lat1) * cos(lat2) * cos(lon2 - lon1)
c = arccos(a + b)
d = R * c
Although this formula is mathematically exact, it is unreliable
for small distances because the inverse cosine is ill-conditioned.
Sinnott (in the article cited above) offers the following table
to illustrate the point:
cos (5 degrees) = 0.996194698
cos (1 degree) = 0.999847695
cos (1 minute) = 0.9999999577
cos (1 second) = 0.9999999999882
cos (0.05 sec) = 0.999999999999971
A computer carrying seven significant figures cannot distinguish
the cosines of any distances smaller than about one minute of arc.
The function min(1,(a + b)) could replace (a + b) as the argument
for the inverse cosine for the same reason as in Sinnott's Formula,
but doing so would "polish a cannonball".
5.1a: What value should I use for the radius of the Earth, R?
The historical definition of a "nautical mile" is "one minute of arc of a
great circle of the earth". Since the earth is not a perfect sphere, that
definition is ambiguous. However, the internationally accepted (SI) value
for the length of a nautical mile is (exactly, by definition) 1.852 km or
exactly 1.852/1.609344 international miles (that is, approximately 1.15078
miles - either "international" or "U.S. statute"). Thus, the implied
"official" circumference is 360 degrees times 60 minutes/degree times 1.852
km/minute = 40003.2 km. The implied radius is the circumference divided by
R = 6367 km = 3956 mi
The shape of the Earth is well approximated by an oblate spheroid with a
polar radius of 6357 km and an equatorial radius of 6378 km. PROVIDED a
spherical approximation is satisfactory, any value in that range will do,
R (in km) = 6378 - 21 * sin(lat) See the WARNING below!
R (in mi) = 3963 - 13 * sin(lat)
where lat is a latitude near which the bulk of your calculations occur.
WARNING: This formula for R gives but a rough approximation to the radius
of curvature as a function of latitude. The radius of curvature varies
with direction and latitude; according to Snyder ("Map Projections - A
Working Manual", by John P. Snyder, U.S. Geological Survey Professional
Paper 1395, United States Government Printing Office, Washington DC, 1987,
p24), in the plane of the meridian it is given by
R' = a * (1 - e^2) / (1 - e^2 * sin^2(lat))^(3/2)
where a is the equatorial radius, b is the polar radius, and
e is the eccentricity of the ellipsoid = (1 - b^2/a^2)^(1/2).
5.1b: When is it NOT okay to assume the Earth is a sphere?
A quick test is: Compute the values of R produced by the equation with the
WARNING when you use the highest and lowest latitudes that occur in your
analysis. Compare the results produced by using these two values in your
analysis. If the different results are different enough to cause you to
change your action (or your recommendation, or your interpretation of the
implication of the results, etc.), then assuming the Earth is spherical is
For most purposes, it is quite satisfactory to treat the Earth as a sphere.
If necessary, an ellipsoid can provide a better approximation. Some
standard textbooks that may be helpful follow (reviews are by Steve
Robertson of Tangent Survey Systems in Canada: firstname.lastname@example.org):
Bomford, Guy 1980 _Geodesy_ Clarendon Press, Oxford
Review: For geodetic computations, this is pretty well
the standard in English. It's a cookbook and offers no
Vanicek, Petr, and Krakiwsky, Edward 1986 _Geodesy, the Concepts_
Review: This offers a great, but quite involved, discussion
of the concepts behind geometrical (and all other) geodesy.
Torge, Wolfgang 1980 _Geodesy_ de Gruyter, Berlin
(translated to English by C. Jekeli)
Review: This concentrates mostly on gravimetric geodesy, but
has some geometrical stuff, well explained without too much
Software for solving distance and azimuth problems on the ellipsoid can be
obtained (as of 10/10/96) by anonymous ftp from several sources, two of
which are listed below:
The URL of the National Geodetic Survey (of the National Oceanic and
Atmospheric Administration in the US Department of Commerce) is:
Review (by Ronald C. McConnell of Bellcore:
email@example.com): They have Fortran source and PC
executable versions of both the normal "inverse" great circle
calculations (two lat/long pairs to distance and bearing), and
the less used "forward" calculation (one lat/long pair plus
bearing and distance to the second lat/long pair). They have
both 2-dimensional and 3-dimensional versions of each. The
inverse program works to within a few seconds or a few
minutes, depending on the fortran compiler, of the antipodal
points. The forward program seems immune to any and all
problem locations and pairs of locations. You can choose
among a couple of dozen ellipsoids.
See the read.me file for explanations. The NGS software directory may
contain other listing of interest. Its URL is:
Case is relevant in many URLs - eg: this one.
Another anonymous ftp source for ellipsoid software is the US Geological
Survey (of the US Department of the Interior), at:
Again, see the README file for explanations. The URLs for the USGS
directory and home page are:
5.1c: When is it NOT okay to assume the Earth is an ellipsoid?
The shape the Earth would assume if it were all measured at mean sea level
is called the geoid. The geoid varies no more than about a hundred meters
above or below a well-fitting ellipsoid, a variation far less than the
ellipsoid varies from the sphere. Terrain relief is reported relative to
the geoid. (Paraphrased from p. 11 of the book by Snyder cited above.)
Distances on the surface of the geoid are not particularly meaningful.
However, there are applications, such as long-term prediction of orbits of
Earth satellites, that require better approximations than are provided by
an ellipsoid. Astrodynamics texts, such as
Kaula, William M. 1966 _Theory of Satellite Geodesy_ Blaisdell
Publishing Co., Waltham, MA (This book may be out of print.)
Battin, Richard H. 1964 _Astronautical Guidance_ McGraw-Hill,
New York (There may be later editions.)
may be consulted for further information.
Distances on the surface of the terrain, whether geodesic, on roads,
cross-country, or straight-line, depend on relief (including elevation
differences), the status of engineering projects, and perhaps even route
selection. Hence, computation is idiosyncratic and not well suited to
Q5.2: What is GPS?
More information is available from:
Richard Langley <firstname.lastname@example.org> maintains a
list of GPS informations sources.
From: Ed Keller <email@example.com>
Greg Holmberg <firstname.lastname@example.org>
Don Cooke <email@example.com>
GPS consists of three parts: the 24 satellites, a portable receiver, and the
control center on Earth. Each satellite carries a computer
and a very accurate atomic clock.
The control center calculates each satellite's orbit a week or
so into the future, predicts ionospheric conditions over that time, and then
uploads this information into the satellite's computer. This information is
called the "ephemeris". By consulting its clock and the ephemeris, the
satellite can tell where it is in the sky at any given microsecond during
the week. It transmits its position and the current time continuously.
Each receiver has a less accurate clock. When activated, it listens for
satellites that are scheduled to be above the horizon each satellite has its
own assigned radio frequency).It then subtracts the first received time from
the time on its internal clock. This gives a distance, which can be pictured
as a sphere around the satellite several hundred miles in diameter. The next
signal will define a similar sphere, and the intersection of the two is a
circle which passes through the Earth.
If the system were ideal, a second time and location signature from another
satellite would give a precise triangulation. In reality, three signals are
needed simultaneously for latitude and longitude, and a fourth is required
for fixing altitude in steps of less than a few hundred feet.
The reason for this apparent gross inaccuracy is a DoD policy called
"Selective Availablity". he satellites are instructed to "dither" both their
times and their locations, that is, they round off their transmissions into
less accurate steps. This is done mainly to prevent a foreign military power
from using the GPS as a free,super-accurate,preinstalled targeting computer.
There are two ways to use GPS to find your position. The first technique
(discussed above) gives instant results anywhere with just one receiver. The
penalty is the decreased accuracy. You can expect a single receiver
GPS-calculated position to be within 100 meters of where a surveyor would
place it. The best measurements are made when three satellites are 120
degrees apart around the horizon, and the fourth satellite is directly over-
head. If you desire greater accuracy, the arrival time of the signal at the
receiver may be compared with that of signals received simultaneously
at another location whose exact coordinates are known.The difference between
these two sets of data yields a location accurate to within 0.5 to 20
meters, and is known appropriately as "Differential GPS".
If you desire even greater accuracy, the underlying carrier wave of the
signals can be analyzed after capture, and compared with signals received
simultaneously at another known location. The difference between
these two sets of data yields a location accurate to within a centimeter.
Why does the GPS signal include ionospheric data when timing
data would suffice?
The ionosphere is a high-altitude layer of the Earth's atmosphere that
receives punishing amounts of solar radiation. This radiation ionizes the
gases, causing the layer to have varying permeability to radio waves. As the
thickness of the ionosphere changes, the GPS signal (coming from outside the
atmosphere is slowed briefly by a predictable amount. If this deceleration
is accounted for in the receiver, the timing skew can be subtracted, and
greater accuracy is achieved.
GPS Satellite Surveying by Alfred Leick (John Wiley & Sons, 1990) or
Guide to GPS Positioning by David Wells et al.
"Poor Man's Cruise" front page,Wall Street Journal, August 26, 1993
GPS World Magazine GPS Report (pricey)
P.O. Box 10460 7811 Montrose Road
Eugene, OR 97440 Potomac MD 20854
and an excellent primer on GPS "the new utility" from Trimble:
645 North Mary Ave
Sunnyvale CA 94086
Q5.3: What can you tell me about map projections?
From: John Ganter <firstname.lastname@example.org>
Map Projection Bibliography:
The "bible" of map projections is often considered to be:
Snyder, J. P. 1987, Map projections--a working manual: U.S. Geological Survey
Prof. Paper 1395, 383 p. Reprinted 1989 and 1994 with corrections.
[General work superseding Snyder, 1982, Map projections used by the U.S.
Geological Survey: U.S. Geological Survey Bull. 1532.]
Available for $32 + 3.50 S/H from: USGS Information Services, Box 25286,
Building 810, Denver Federal Center, Denver, CO 80225, 303-202-4700; Fax
Q6.1: What are e-mail and paper addresses, and WWW sites of some vendors?
For a complete USMail address list of GIS and mapping vendors, consult
the GIS Sourcebook (annual) from GIS World Magazine.
Caliper Corporation Product: GISP+, Maptitude
1172 Beacon Street TransCad, GISDK
Newton, MA 02161
(617) 527-5113 (Fax)
email@example.com (product information)
firstname.lastname@example.org (technical support)
Coherent Research, Inc. (CRi)
One Adler Drive
East Syracuse, NY 13057
Election Data Services, Inc
1225 I St NW, Suite 700
Washington DC 20005
The place to call for just about anything related to USA
EROS Data Center
Mundt Federal Building
Sioux Falls, SD 57198
Customer Services: 605-594-6151
Environmental Systems Research Institute (ESRI)
380 New York Street,
Redlands, CA USA 92373
For Help with ESRI products, you can send email to the above address.
In correspondence be sure to include your name, organization, system,
OS revision, Arc/Info revision and your ESRI client number (if you know it).
The e-mail address for more info on the Etak road map and vehicle
navigation software is email@example.com.
"genasys-l" the mail list for users of Genasys related GIS.
Subscription requests made to:
Body of message to include...
subscribe genasys-l firstname.lastname@example.org (Your Name)
Generation 5 Technology, Inc. Products: Geo/SQL,
Sheridan Park 8
8670 Wolff Court
Westminster, Colorado 80030 Phone: (303) 427-0055
Geographic Data Technology, Inc. (GDT)
11 Lafayette St
Lebanon NH 03766
800-331-7881 (sales/voice mail)
Tel.: +49 2173 9153 10
Fax.: +49 2173 9153 30
(geographic technical informationsystem/relational database)
Digital Matrix Services, Inc.
3191 Coral Way, #900
Miami, FL 33145
Ph: (305) 445-6100
Fax: (305) 442-1823
BBS: (305) 529-9303
Ingres (Intelligent DataBase), An ASK Company (this may be of new
interest here because of the ability to define data types in the
database, such as polygon, line, etc )
1080 Marina Village Parkway
Alameda, CA 94501-1041
510-769-1400 or (NA only) 1-800-4-INGRES
Ingres' email address: email@example.com A volunteer
address for referals: firstname.lastname@example.org
Utilities & Mapping Sciences Division
Huntsville, Alabama 35894-0001
Mail Stop: IW17B5
U.S. 800-345-4856 (toll free)
Canada 800-461-5297 (toll free)
Middle East 971-4-367555
All Other 205-730-2700 (U.S.)
522 South Road
Poughkeepsie, NY 12601-5400
Graphics Program Generator (GPG)
One Global View
Troy, NY 12180
Sales: 800-FAST-MAP email@example.com
Tech Support: 800-552-2511 firstname.lastname@example.org
SHL Systemhouse Inc.
50 O'Connor Street, Suite 501
Canada K1P 6L2
SHL Systemhouse's email address: email@example.com
I can be contacted at firstname.lastname@example.org.
GeoVision Systems Limited
80 Park Street
Camberley, Surrey GU15 3PT
Tel: 0276-677707 (From North America 011-44-276-677707)
SICAD (BS2000) and SICAD/open (Unix)
For the USA:
Information Systems Inc.
200 Wheeler Road
Burlington MA 01803
Phone (617) 273 0480
Fax (617) 221 0231
International Business Development
Smallworld Systems Ltd.
61-69 Newmarket Road
Phone (UK): 0223-460199
Grid ref (UK): TL 460 589
Strategic Mapping Inc Products: Atlas GIS, Atlas Graphics ...
3135 Kifer Road
Santa Clara, CA 95051
Telephone: (408) 970 9600
(408) 970 9977 (Product Support)
Facsimile: (408) 970 9999
SYSTEM 9 can be reached at the following address:
61 Middlefield Road
TYDAC Technologies Inc. Product: SPANS
2 Gurdwara Road
Canada K2E 1A2
tel: (613) 226-5525
fax: (613) 226-3819
For questions, queries or quandries in regards to our product please contact
Q6.2: What public domain or shareware GIS/carto software is available and where is it?
This list seems to be growing with software that does indeed
have a price, so the wording of the question may be misleading.
You can buy it for $60 from the AAG Microcomputer Specialty Group.
Send all Atlas GIS for DOS orders to
Eugene Turner, Dept of Geography, California State U, Northbridge
Purchase orders acceptable, but checks perferred.
General Cartographic Transformation Package or GCTP
This is a package of FORTRAN procedures that provides
forward and inverse projection of about 23 cartrographic
projections. It is the "official" system of the National Mapping
Division (NMD) of the US Geological Survey. It also provides
conversion of State Plane Coordinate System. It is documented
with *.txt, *.ps and word processor files as well as hard copy
It is currently available via ftp from:
as file public/amdahl/gctpv2.dat
It is also available from:
Phone: 1-800-USA-MAPS Fax:: (703) 648-5548
At the moment, prices for mail-order material is unknown.
For software questions and assistance contact:
Phone: (703) 648-4667 Fax: (703) 648-4722
U.S. Geological Survey
510 National Center
Reston, VA 22092
The General Cartographic Transformation Package (GCTP) was converted to the
C programming language, and several new projections were added. This new
version, GCTPc, is being made available informally by EDC. The directories
and files containing this package are available via anonymous ftp.
Periodic updates and corrections will be put in this directory for access
by the science community. Descriptions of these updates will be added to
the README file in the main directory.
The Package has been tar'd and compressed under the directory name gctpc.
To access GCTPc, retrieve the file gctpc.tar.Z by anonymous ftp from
This file can be retrieved by following these steps:
ftp> cd pub/software/gctpc
ftp> get gctpc.tar.Z
Then on a UNIX system type:
% uncompress gctpc.tar
% tar -xvf gctpc.tar
The National Geodetic Survey (NOAA/NGS) provides many FORTRAN procedures
and DOS programs for cartographic projections as well as datum
conversions and other geodetic information. At this moment,
the only way to get this material is by phone or mail ordering
although there appears to be some effort afoot to establish
Contact (they take plastic):
NOAA, National Geodetic Survey, N/CG174
1315 East-West Highway, Station 9202
Silver Spring, MD 20910-3282
Phone: (301)713-3242; FAX (301)713-4172
Mon-Fri 7 a.m.-4:30 p.m. Eastern Time.
For complete list of products, ask for "Catalog of Products
and Services of the National Geodetic Survey" and "Geodetic and
Charting Publications". Prices are nominal for most software
products (~$30 US) and *certainly* better than the $90+ they
were charging in 1992.
GIV Geologic Information Visualizatio mapping software
This PC based software from the USGS allows a user to turn a paper
map into digital data, display and manipulate different image
types, combine maps with images and text, and integrate data.
Contact Christine Cook, USGS at 703-648-6481 (email email@example.com)
GeoSim, developed at Virgia Tech depts of Geography and Computer Science
Project GeoSim consists of a series of self contained modules that
serve as lab excersizes compatible with intruductory geography
courses. These modules are appropriate for students at both the
undergraduate and high school level. Educational goals are based
on the widely adopted 'Guidelines for Geographic Education' (1994)
co-authored by GeoSim team member Robert W. Morrill.
GeoSim modules are interactive, allowing students to make decisions
and manipulate geographic data in ways that encourage learning while
maintaining student interest. The software runs on PCs, Macintoshes,
and machines running X-windows. The modules include: Migration
Modeling of the US, Migration and Sense of Place, Migration and
Political Power in the US, Human Population, and Maps and Mapping.
The software is available vi ftp and gopher at geosim.cs.vt.edu
or via the WWW at
ivmaps, a package of map display software for USGS and DMA digital
map data, is now available. It can be retrieved via e-mail by sending
"get ivmaps ivmaps-0.4.1.tar.gz" as the body of a message (no
subject required) to firstname.lastname@example.org, or ftp'ed from
ivmaps is a collection of C++ class libraries and example display
programs that support both DLG and VPF map formats in a common
framework. Built on PROJ-4.3, ivtools-0.4, InterViews 3.1, and
Unidraw, the software represents a reasonable starting point for the
construction of custom interactive map-based user interfaces.
Currently supported databases include DCW and DLG 1:2M. ivmaps has
been built and tested on the following Unix/X11 platforms:
SunOS 4.1.3 (MIT's X11R5, gcc-2.5.8)
Irix 5.2 (SGI's X11R5, gcc-2.6.1)
Linux 1.2 (Slackware 2.2, XFree86 3.1, gcc-2.5.8 and gcc-2.6.4-elf)
It should be fairly straightforward to build on other Unix platforms
with gcc, and perhaps with other compilers as well. Please send us diffs
and build instructions for other platforms if you are able to build it.
- Hybrid vector/raster map server for user-written client applications -
megatelVISOR enables the user to perform complex manipulations of
text and graphics data against a map background.
The core of megatelVISOR is a so-called "VIEWER" which allows to
record, store and recall maps (drawings, pictures, charts, etc. )
of any magnitude. The magnitude of the scanned maps is only limited
by mass-storage capability restrictions.
The map-data input, i.e. the scanning of the graphic mass data
(maps, plans, aerial reconnaissance photos, etc.), can be done by a
standard scanner . The data are then compressed and stored on hard
disk or CD. The handling of the scanning process and the storage is
very simple, so that non-technical users may scan the maps without
difficulties. The stored maps can be accessed from MS-DOS and UNIX
UNIX users of megatelVISOR via network.
megatelVISOR via network.
megatelVISOR supplies diverse functions for graphic vector editing
on the map (drawing, moving, copy/paste, colouring, hatching etc)
that are provided by standard graphics systems running under
MS-WINDOWS 3.1, NeXTSTEP, OpenStep and X-WINDOWS, Windows NT.
The input for the generation of the vector layers is possible from
the workstations manual I/O facilities (keyboard and mouse) as well
as the import of vector data from ASCII delimited format (DXF and
The vector-management system of megatelVISOR 1.5 consists of a
new geometrical-database, based on a reorganisation-free
v-tree-index procedure that provides a very fast access even when
there is a very high number of vector objects to handle.
Features of the resulting map (basic rastered map plus vector layers)
are configurable from menue, which is adapted and similar to that
of the graphical user interface GUI (e.g. MS-WINDOWS, NeXTSTEP,
MOTIF ) so that non-technical users can perform all editing
megatelVISOR is a universal front-end for graphical applications.
The VIEWER exchanges messages with other applications via DDE
(MS-WINDOWS VIEWER) TCP/IP and Distributed Objects (UNIX Viewers).
This includes external control of viewing functions, drawing by
other applications as well as editing these (or new) objects in the
VIEWER and sending them to the appropriate application.
The incorporation of data files compatible with ASCII delimited
format is possible. By (Mouse-Click-) adressing a layers graphical
information (i.e. point,polygon or area) the target information of
the database (or the text processor) will be searched and displayed
with all stored attributes. Reversely the results of database
manipulations may be displayed on the layer/map.
Possible applications include technical documentation and land
Prices (1Q1996) DM 7800.00 plus VAT.
The program package megatelVISOR consists of several parts.
Item prices in Deutsche Mark (DM) are given without VAT:
Number of licenses 1 2-9 10 and more
Viewer 3950 3550 3250
Toolbox 3950 3550 3250
Additional DXF-Interface DM 230.
You only need the toolbox if you want to generate maps from scans.
Please address project specific questions to
R. Gath, Dr. H. Bischoff
Wiener Strasse 3, D-28359 Bremen, Germany
Tel. ++49 421 22095-0 , Fax ++ 49 421 22095-16
GMT (generic mapping tool) by Paul Wessel, School of Ocean and Earth
Sciences and Technology (SOEST) / University of Hawaii can
- display various kinds of fancy maps (Postscript from formatted ascii
- apply diverse analyses (fits, contours, fft, etc) on the data
- transform to many coordinate systems
- run in connection with NetCDF
- be used in connection with own routines
more info can be got from reading the (thick) manual.
GMT documentation & sources: anonymous ftp from kiawe.soest.hawaii.edu
(220.127.116.11). in the pub/gmt directory
GMT uses several functions in the netCDF library. Copy the file
netcdf.tar.Z from unidata.ucar.edu (18.104.22.168) using anonymous ftp.
Then uncompress/tar and follow their instructions for installation.
The U.S. Army Construction Engineering Research Laboratory's
(USA-CERL) Geographic Resources Analysis Support System (GRASS) was
developed to provide management tools to Army environmental
planners and land managers. GRASS also has many applications for Civil
Works project planning and design. GRASS has many capabilities,
including the handling of different representations of data:
RASTER DATA -- raster (or grid cell type) data can be used for
analyzing, overlaying, and modeling areal features such as soil types
or forested areas.
VECTOR DATA -- vector data can be used to represent linear features
such as roads, streams or area edges and can be combined with raster
data for display purposes or for analysis.
POINT DATA -- point data can be used to represent landmarks or the
location of significant sites.
From: email@example.com (Scott Wade)
One way to obtain GRASS is via anonymous ftp from moon.cecer.army.mil
[22.214.171.124]. It is available at any time.
This is complete message form Office of GRASS Integration:
From: Ken Brownfield <firstname.lastname@example.org>
The OGI GRASS FTP server has been moved and reorganized.
The FTP site is now available 24 hours a day, seven days a week. (!)
The name of the new FTP site machine is still moon.cecer.army.mil, but
the IP number has changed to 126.96.36.199. From any Internet
machine, moon.cecer.army.mil should still work fine. After connecting
to the moon, change your directory (using cd) to the grass directory.
Since the new site is shared between many offices here at cerl, grass
is in its own directory on the ftp site.
The site has been reorganized in a more intuitive manner, so programs
and updates should be easier to find. When GRASS v4.1 has been
released, bug fixes will be separated from new programs and existing
program _upgrades_. We hope that the lifted time limitations will give
everyone a chance to access the FTP site at normal working hours. If
you have problems, comments, or suggestions, please send mail to ftp-
MOSS for the IBM PC can be found on ftp.csn.org [188.8.131.52] in the
PC MOSS contact: Sol Katz email@example.com
FTP contact: Bill Thoen <firstname.lastname@example.org>
I have recently posted the source code to PC MOSS at ftp.csn.org. To get it,
ftp to ftp.csn.org and look in the COGS/MOSS directory for mosssrc.zip
and mosssrc2.zip. It's public domain code and written in
FORTRAN. MOSS is a vector-based GIS system widely used by the
US BLM and others. The workstation version is several revs ahead
of the PC version, and (in case you're wondering) the PC version is
no longer being updated.
The MOSS source code (and many other GIS-oriented files not on this
ftp site) can also be found on GISnet BBS. GISnet's number is
(303) 447-0927, (Boulder, Colorado) and you can call anytime at 1200,
2400, 9600 baud. However file downloading from GISnet requires a
subscription ($48/yr), but you *can* download the full list of files,
and a few other files for no charge.
Please don't ask me questions about how to compile, link, etc. or
anything about the algorithms involved in this code. I just put
this out there because I think it may be of interest, but I can't
offer tech support, because I don't know it very well myself, and
besides, the code is fully self-documenting anyway... (muhaha!)
The source code for PC MOSS as well as the executables (and manual)
are on ftp.csn.org (128.138.313.21) in the /COGS/MOSS directory.
The pc code is several rev's behind the current version.
Current version is available from the blm in prime magsav
format for about $250. or in ascii for about $500. (cost of distribution).
also autometric inc. distributes an UNIX X-windows version, contact
them at 303-989-6399 (fax 303-989-5799)
Although MOSS is PD, to my knowledge, no one who has acquired it has posted
it on a FTP site. The vector portions of the current version have been
ported to 3 different operating systems. It is believed that a port to the
PC would not be difficult.
For those brave souls who might be considering porting PD MOSS to
a new platform, a copy of the moss programmers manual has been uploaded to
dsc.blm.gov in the ftp/pub/gis directory.
Arcview 1.0 for Window 3.x
Available via ftp at
Arc Digitised Raster Graphics (ARDG)
From: email@example.com (John Schuster)
Code for viewing ADRG (Arc Digitised Raster Graphics) files is
available on the GRIPS II CD-ROM. The U.S. Army Engineer Topographic
Labs (Juan Perez) gave me permission to post the code on the net, so
I've posted adrg.zip to spectrum.xerox.com. The GRIPS II (Gov. Raster
Image Processing Software) CD-ROM is available from CD-ROM Inc. at
1-800-821-5245 for $49. Special thanks to Peter Z. Simpson for
pointing this out.
OzGIS Mapping System Version 10.3
OzGIS is a software system for displaying geographically referenced
data, such as Census data or environment data, as maps and diagrams on
screens, printers and plotters on an IBM PC compatible. DOS and
WINDOWS versions are available.
The OzGIS mapping system is available for anonymous ftp from many sites.
Both DOS and WINDOWS versions are available from the SIMTEL20
archive and mirrors:
OAK.Oakland.Edu (184.108.40.206), wuarchive.wustl.edu (220.127.116.11),
archive.orst.edu (18.104.22.168), ftp.uu.net (22.214.171.124), nic.funet.fi
(126.96.36.199), src.doc.ic.ac.uk (188.8.131.52), nic.switch.ch
(184.108.40.206), archie.au (220.127.116.11), or nctuccca.edu.tw (18.104.22.168).
The WINDOWS version is available on the major FTP site ftp.cica.indiana.edu
and mirrors in directory pub/pc/win3/misc:
530-USA Sites: wuarchive.wustl.edu [22.214.171.124]
530- gatekeeper.dec.com [126.96.36.199]
530-Non-USA Sites: monu6.cc.monash.edu.au [188.8.131.52] (Australia)
530- nic.funet.fi [184.108.40.206] (Finland)
530- ftp.uni-stuttgart.de [220.127.116.11]
530- ftp.iij.ad.jp [18.104.22.168] (Tokyo)
530- ftp.technion.ac.il [22.214.171.124] (Israel)
530- src.doc.ic.ac.uk [126.96.36.199] (London)
The DOS software is available as 7 files OZD101A.ZIP to OZD101G.ZIP, and
the WINDOWS version as 13 files OZW103A.ZIP to OZW103M.ZIP
You should also get a copy of Info-ZIP's free portable UNZIP program,
which is recommended for these archives. It is file unz50p1.exe in directory
/pub/msdos/zip This is a self extracting file i.e. just type UNZ50P1 and you
end up with UNZIP.EXE which you use as e.g. "UNZIP OZD103A" to unpack each
of the files.
You should look at the file OZ*A.ZIP first as it contains a set of example
maps and basic specifications as text files. You need to put the file in a
new \OZGIS on your PC hard disk,UNZIP it, and type OZDEMO. The demo displays
a series of saved screens (standard VGA) that should give a good idea of the
capabilities of OzGIS.
DOS6.0: 286, 640K ram, EGA, 8meg disk
WINDOWS3.1: 386+, 4meg ram, mouse, 8meg disk
The basic price of OzGIS (until end 94) is A$500 (US$350), with educational
discounts and various options. VISA and Mastercard accepted.
See the ORDER.DOC file.
OzGIS is developed by The Clever Company, QMDD box 6108,
Queanbeyan, Australia 2620.
The Defense Mapping Agency (DMA) is also a source of considerable
cartographic software and information. Unlike the NMD/USGS
and NGS, DMA information is international in scope. Some products
(mostly maps) are sold through the USGS, but an outlet for software
and other geodetic information is currently unknown.
Fractal Landscape Generators
Many people have written fractal landscape generators. For example
for the Mac some of these generators were written by
firstname.lastname@example.org (Paul D. Bourke).
Many of the programs are available from the FTP sites and mail
archive servers. Check with Archie (a well known example is Fractint -
besides fractal images, it generates height fields).
U.T.M. and State Plane Coordinate Conversion Software
This program by John Banta is Windows shareware and is available at
R2V for Windows and Windows NT, a raster to vector conversion system.
The system combines the power of automatic digitizing technology
with a menu-driven graphical user interface in the Microsoft Windows and
32-bit Windows NT environment.
Input: Images in TIFF format, supports bi-level, gray scale and color images.
No software limit for image sizes.Also supports SPOT satellite image
Output: MapInfo(MIF), DXF, ArcView 2 and Arc/Info vector file formats
and TIFF format for images.
Vectorization: Fully automatic and fast. It extracts vector data from maps,
aerial photos and even satellite images of bi-level, gray scale
or color types.
Vector Editing: A complete vector editor is provided using the scanned image as
Image Processing: Vertical and horizontal flip, transpose, crop a region,
smoothing using median filter, negate. Pixel values can be viewed
in realtime using the Pixel Tool. Various image type conversion
Vector Registration and Merge: Registration is performed using a geometric
transformation derived from user specified control points. Multiple
vector sets can be merged into a single set.
Print: Any printer supported by Windows.
Demo: A demo version of the system is available by anonymous ftp at
or disk by request.
Prices: US$1495.00 US$960.00 for educational use.
For more information, please contact:
Able Software Co., 5 Appletree Lane, Lexington, MA 02173
Phone: 617-862-2804 FAX: 617-862-2640
Q6.3: Will GRASS run under LINUX OS on my PC?
From Mark Line <email@example.com>
For GRASS 4.1
I've found these binaries to be plug-and-play. They're the newest version
You can mention me (Mark) as a source of information on GRASS
on Linux, if you want.
Q6.4: How do you convert ARC coverages to IDRISI?
From: Mike Killion <firstname.lastname@example.org>
To convert an ARC/INFO coverage to an IDRISI image (.img) file -
1) use the ARC command POLYGRID to convert the ARC coverage to an ERDAS
16-bit file (there are other options,but this one has been the least trouble
in my experience.) You will need to provide the coordinates of the lower
left corner of your coverage,and information about cell
size(cell resolution, number
of rows and columns), and you'll need to specify one numeric item to be
used as the "z-value" for the new raster image.
2)use the IDRISI command ERDIDRIS (locate under the Import/Export menu) to
convert the ERDAS file to an IDRISI image file. Before the new IDRISI image
can be used, you'll have to create a documentation file for it.
Another option is to UNGEN your ARC coverage then use the 3DRISI command
3RCIDRIS, but I've never had much luck with this one.
Q6.5: How do I convert ARC coverages to GRASS?
[Ed. note: As with most lists, this one has been edited
due to length.]
For help with ESRI products and importing or exporting data formats,
see the ESRI web site
From: Steve Bower <steveb@VCGI.UVM.EDU>
SUMMARY: Arc/Info -> GRASS data conversions.
TOPIC: Convert a polygon coverage from Arc/Info to GRASS
Use a coverage named 'school' as an example to show the procedure:
STEP 1. --- Get data out of Arc/Info
1.1 get line data
Arc: ungenerate line school school.lin
1.2 get label point data
Arc: ungenerate point school school.lab
1.3 get label text (attribute) data from INFO
ENTER COMMAND >OUTPUT ../school.txt
ENTER COMMAND >SELECT SCHOOL.PAT
12 RECORD(S) SELECTED
ENTER COMMAND >LIST PRINT (See Note2)
ENTER COMMAND >Q STOP
school.txt should look like this:
$RECNO AREA PERIMETER SCHOOL# SCHOOL-ID SCHOOL-NAME
1 -2.46815E+09 216,729.700 1 0
2 3.871248E+08 121,106.100 2 5 Springdale
3 2.923594E+08 114,518.100 3 11 Fayetteville
4 2.754085E+08 144,500.300 4 6 Prairie Grove (See Note1)
5 83192210.000 54,980.120 5 7 Farmington
6 98547120.000 53,769.720 6 4 Siloam Springs
7 3.852254E+08 112,999.100 7 3 Lincoln
8 2.611844E+08 101,406.700 8 1 Elkins
9 1.898218E+08 112,633.000 9 8 Greenland
10 2.734009E+08 101,322.400 10 9 West Fork
11 1.676338E+08 66,904.990 11 2 Winslow
12 54256160.000 32,175.590 12 10 West Fork
STEP 2. --- Bring data into GRASS
2.1 create a subdirectory called 'arc' in your current mapset if necessary
and copy school.lin school.lab school.txt to the 'arc' directory
GRASS 4.1beta>v.in.arc type=polygon lines_in=school.lin points_in=school.lab
text_in=school.txt vector_out=sch_dist idcol=5 catcol=5 attcol=6
GRASS 4.1beta > v.support map=sch_dist
Note1: If the attribute text contains blank,(for example,Prairie Grove), the
second word is dropped after running 'v.in.arc'. My only suggestion
is to edit the dig_cats file so that the complete attributes can be
Note2: If the PAT file contains a lot of columns, you have to use the INFO
command - REPORT to create a report which looks like the above
example(school.txt). For more information about REPORT refer to
INFO Reference Manual.
1) UNGENERATE the ARC coverage. Coverages that will end up as GRASS
vector files need only lines, e.g. UNGENERATE lines <your_coverage>.
Those that contain polygons and are destined to become raster layers
need lines and points, eg:
UNGENERATE lines <your_coverage> <lines_output_filename>
UNGENERATE points <your_coverage> <points_output_filename>
Next, use DISPLAY or PRINT (I think-- this is from memory) from within
INFO to print out the fields you need from the database.
2) Move all of the ungenerated files and the database text files to
$LOCATION/arc-- you'll probably have to create the arc directory
yourself. The files MUST be in this directory. $LOCATION is defined
by GRASS at startup, so if you mv them from within a GRASS session,
they'll go to the right place.
3) Use v.in.arc to suck the files into GRASS. The g.manual entry
explains things pretty well. This is probably where problems will
occur if any occur at all. This program is touchy about the format of
the ungenerated file.
4) Run v.support on the resulting file. Be sure to use the <build>
option. In my experience, v.support generates tons of error messages,
but few of these are ever significant, so don't let them throw you.
5) Run v.digit on the v.support output. At a minimum, run v.digit with
no digitizer (mouse mode), fill in the information regarding scale,
window boundaries, etc, then let v.digit draw the file. When it
finishes, you can either save the resulting vector layer as is or
modify it. If it is destined for raster-hood, you should probably
check and make sure that all polygons are closed-- see the v.digit
tutorial for additional details if you need them.
6) If you want to build raster coverages, run v.to.rast on the vector
layer after v.digit. As I recall, v.to.rast creates a HUGE temporary
file, so be sure you have lots of disk space available.
7) Run r.support to assign a color table, check category labels, etc.
Voila-- you're done!
Michael Camann email@example.com
Q6.6: Where can I find some AMLs to look at?
AMLs and other ESRI scripts are available at
For information on ESRI Inter-Application Communication, with AML, Avenue,
and Visual Basic code samples, see:
And there is the following book:
ESRI part number 420259
ARC Macro Language: Developing ARC/INFO menus and macros
The unit price is $50.00 (U.S.) and discounts are available as
10% for university faculty & students (copy of valid
10% discount for federal government
40% discount for educational institutions and bookstores
Shipping: $10 for surface; $15 for second-day air; $26 for
Sales tax: payable in many states
Form of payment: check, purchase order, or Master Card/Visa
Attn: Customer Support Workstation
380 New York Street
Redlands, CA 92373
Fax: (909) 793-4801
Telephone: (909) 793-2853, ex. 2050 (credit card orders only)
THE ABOVE IS DOMESTIC U.S. ONLY! INTERNATIONAL ORDERS MUST BE
PLACED THROUGH THE LOCAL ARC/INFO DISTRIBUTOR.
Q6.7: How can I convert ARC files to some other graphics formats?
Summary From: Fred J. Calef III <mapduxbury@UMBSKY.CC.UMB.EDU>
POSTSCRIPT: It seems the postscript file Arc/INFO makes is not a
true Encapsulated Postscript File. It seems to be a little more
than a plain postscript file but not quite an EPS file. Here are
1) Use the unix2dos command on unix systems to add control-returns
to the file which dos needs to read the file properly (Arc/INFO's
postscript file being an ASCII file)
2) FTP the file using the ASCII option because the postscript file
is in ASCII format
3) Use the Ghost Script utility (available via FTP) to read the file,
then output it in EPS format.
****As a special note, GhostScript can be FTPed from prep.ai.mit.edu
in directory /pub/gnu.
4) Use a program that reads pure ASCII postscript files (such as Word on
ADOBE ILLUSTRATOR: This file format is similiar to postscript, but with
some differences (whatever they are). I received some specific responses
to correcting this format.
1) Edit the file and add these lines after the line containing %%EndProlog
(said to be line 8):
This supposedly makes it readable with Corel Draw.
2) Make sure you close the file by issuing another DISPLAY command or
QUITting out of Arcplot. This puts the bounding box around the file.
3) You can run an awk program in the unix environment to fix the file. Here
is the command line:
nawk -f fix_ai.awk bad_ai_file > good_ai_file
Here is the awk program:
# Program to convert Arc/Info Illustrator output so Corel Draw
# can handle it.
This should allow you to read the file in Corel Draw.
TIFF: I have found one way to succesfully bring a TIFF file into the pc
1) FTP the TIFF file using the binary option. Then use Corel Draw (I used
v3.0) to read the file with the PhotoPaint module. This successfully reads
the file,but all of the areas using black are valued as white! On the screen
there should be a pallette tool displaying all of the colors used in the
image. Double click on the white block on the palette to bring up another
tool that allows you to adjust the color to any in the spectrum. Move the
red, green, and blue sliders to the opposite end of the slider spectrum. You
can then press the preview button to see if this gives you the correct color
scheme of the image. Then you can press the OK button to transform the image
to the setting you changed it to. You should have the proper color balance
now. Save the image to keep this change.
(I've tried other programs to read the original Arc/INFO TIFF file, but came
up with a black screen)
Computer Graphics Metafile (CGM): The only response I received about this
format was that they could not successfully use the Arc/INFO generated file.
OTHER WAYS TO CAPTURE IMAGES IN ARC/INFO:Here are some other ways to capture
images in Arc/INFO.
1) IN the UNIX environment, use the SNAPSHOT Utility (available via FTP) to
capture the image off of the screen, then use HIJACK to convert it into
another file format. The resolution is not suppose to be that great.
2) Import your coverages into ARCVIEW, make the image to be captured and use
it to make a WINDOWS BITMAP image.
3) Output to an HPGL file, then use the Wordperfect utility GRAPHCONV.EXE to
convert it to a .wpg file. Review the options of this utility (This solution
came from a recent summary on putting postscript files into Wordperfect).
These are the suggestions, but I have not personally verified them (except
the TIFF suggestion which is my own).There has been alot of talk about these
problems and I hope these possible solutions work out. Maybe ESRI can or has
addressed these problems in 7.0...one can only hope...
Q6.8: How do Arc/Info and Intergraph MGE compare?
Summary from: Chris Wade <firstname.lastname@example.org>
At my company, data Chromatics, Inc. we use both arc/info and intergrpah mge.
We perform a variety of GIS consulting services to public and private sector
clients, with particular emphasis on data integration.
For larger scale implementations, we prefer intergraph for two main reasons:
1. It is based on on industry standard cad package (Microstation) which is
known by most people with cad or mapping experience and
2. The MGE database structure permits full use of standard SQL databases such
Oracle, Informix or Ingres. In Arc, while you can use an oracle database,
you can't use an oracle table...you must use the info table.
Arc is not a CAD package. Since most large scale projects require traditional
input work, your costs can be reduced by selecting a package with a direct
(not translated) cad input function such as autocad or microstation. From
the database standpoint, I can hire a database programmer in Oracle and,
with little or no additional training, have him or her peforming query
development for end users that may not need graphic interfaces. This is not
easily accomplished with arc.
On the smaller scale, Arc can be implemented with less training costs.
There are some good programs from Intergraph that a GIS operation could
probably be happy using. Raster to vector conversion software comes to mind.
The basic product on which all Intergraph is based (Microstation - a CAD
program) is quite good. However I found the following things about Intergraph
to be quite irritating:
1. Since it was built on top of a CAD system, it is essentially a "kludge"
system in my opinion. "Kludge" systems are inherently buggy I think. I
would say that ArcCad probably suffers from the same kinds of problems
(although I must admit I have never actually worked with it before).
2. If you are talking about Unix workstation platforms, then Intergraphs
program only run on Intergraph equipment as far as I know. The I equipment
seems to have a lot of hardware problems. Also the operating system is
based on System 5 unix, and seems pretty primitive after working with BSD
unix on Suns (this is probably another bias, and of course, Sun is moving
to Solaris, which is also System 5 based - bummer!).
3. The software is menu based for the most part, which is probably good for
most users. I however have a problem with "black boxes". I personally like
command line software, because I feel I have a better understanding of exactly
what I am doing. It is harder to learn of course. Even though Intergraph is
menu based, there seems to be a excessive amount of system files that have
to be dealt with by hand. I don't understand why the software does not take
care of many of these files for the user. The idea of a menu interface is
supposed to protect the user from this kind of problem
4. Packaging is a REAL problem I think. With Intergraph you have to buy a
whole bunch of individual packages to put together a usable system. Most of
the programs have descriptive names such as IPSNUC27, which is very informative
to they purchaser (don't let the sarcasm drip on you). I don't think the
sales people understand all the different pieces much less the prospective
buyer. A/I (for the moment at least) comes more or less bundled. The basic
package lets you do most of the GIS things you need to do. Add on's like
COGO, are also bundles of programs.
5. Documentation is terrible, although it looks impressive on the bookshelf.
6. Creating your own menuing interface is a major problem with Intergraph.
They use a programming language (MDL) which is very similar to C, but is not
truly compiled. A/I's AML is much easier to develope with in my opinion. Of
course, if you want to be sure you will be invaluable to your boss (assuming
they commit to Intergraph), then do a lot of programming in MDL. This should
guarantee job security because there are so few people who understand/want to
program in this language.
My impressions so far of Intergraph is that it is seems very hard to use
(remember my A/I bias here). It is very different to A/I in its layout and
how it requires you to do things but the end result will be the same. It
has a wonderful windows interface and this helps immensely. It is much more
stable than Arctools and heaps easier than command line entry and AML
programming. However, for the dedicated types, there is a command line to
do everything and you can customise Intergraph (though not as easily as A/I,
but many wouldn't need to due to the friendly user interface which already
exists). Intergraph can be run in batch mode so that many processes can be
automated such as refreshing point coverages to take into account database
changes that may have occurred during a days operations. Intergraph handles
graphics better than A/I, that is because all graphics are controlled
through Microstation CAD which is the core of the Intergraph GIS, as you
probably already know.
I feel that once I am used to Intergraph software I will be away laughing.
All the functionality is there and then some ie Remote sensing and 3D add
I think that the dominant application that your GIS system will be put to is
the most important thing to consider. If you are doing AM/FM, such as
utilities management and lots of CAD type stuff than definitely go with
Intergraph. Microstation is a wonderful CAD package and the GIS
functionality is built on top of this. Intergraph has great 3D
functionality and this appeals to us for its potential in monitoring air and
groundwater pollution, flood hazard assessment etc etc.
If your needs are more thematic and natural resource information based, then
Arc/Info probably has the edge.
You probably have a short list of essential things you need to do - like
build a parcel database. My brother Kip White, who works for El Paso
County, CO, has just completed 1,500,000 parcels out of 3,000,000 using
his Arc/Info system 6.1.1. So it works ;-) Note that these parcels are not
digitized, but entered from plats using COGO measurements. You should
probably do it this way and use GPS too for best accuracy. Lots of hard
work. He has a group of 5 working with him on an older VAX installation.
I'd ask for references, descriptions, and/or
demos from each company. I've found I get a warm and furry feeling
talking to people who were in my shoes a year a year ago.
AMLs are a nice way to automate tasks for a particular situation.
I'm an Arc user too, but I think some of the CAD technology in
Microstation, which is what I'm familiar with on the Intergraph side,
is second-to-none. I like the way Intergraph is efficient vis-a-vis
digitizing techniques and drawing file sizes. Speed of access is
very good to.
So get yourself both! Arc/Info imports the IGDS files ;-)
Intergraph's approach is to develop generic application that are built on
their basic software of Intergraph Graphic Design Software (IGDS).
Applications such as Scan Data Capture, which was sold as a
separate software package were primarily macros written
to combine IGDS functions. Whereas ARC/INFO gives
you the "tool box" to develop your own specific applications.
If you have the staff to write and maintain you applications, I feel that
ARC/INFO is the way to go. However, Intergraph's support (both hardware and
software) were fantastic. You had only one number to call and get you
problems taken care of.
I use and teach both systems on a regular basis. Like you, I cut my teeth
on ARC, but I have used MGE and other Intergraph products enough to
be fairly comfortable (I've even switched from using Erdas for remote
sensing to Intergraph's ISI).
connecting to a database:
MGE on Clix or NT -- incredibly simple because of RIS
ARC -- takes some work
MGE -- uses Microstation for graphic manipulation, very nice CADD product
ARC -- arcedit and ADS are clumsy in comparison
simplicity of use
MGE -- more complex to learn than Arc, requires more "gis" knowledge
ARC -- relatively easy to learn despite the number of giga-commands
MGE/Intergraph -- incredible amount of stuff that interfaces directly to
MGE, we have retired our digitizers and use their
vectorization (GEOVEC) and character recognition
(ISCR) software for data capture
ARC -- ADS and ARCSCAN (Haven't used ARCSCAN)
MGE ---on Clix (System V unix) or NT (I love NT, this comes from an
affirmed unix head who has Linux on a home computer). NT is
a stable and reasonably fast operating system. Setting up the
network is laughably simple as is connecting to databases.
ARC --Runs great on Unix boxes (I'm most familiar with SUN OS)
It's difficult to compare performance, since the platforms are so
different. MGE runs on WinNT or an Intergraph Clipper with UNIX. I tried
out the proprietary Clipper box. Even on the Clipper, MGE is not very
standard, it uses a proprietary graphics interface instead of XWindows.
The ARC/Info package, on the other hand, runs on most popular UNIX
platforms (I used a fast Sun SPARC10) and uses XWindows for graphics.
It's almost impossible to compare the performance between these two
very different platforms. Both seemed acceptable in performance.
Both products are "loaded". I'm confident that either will be able to
"get the job done", regardless of the requirements.
1A. MGE architecture: MGE is built around a CAD system. If the planned
geo-system is CAD-intensive, then MGE has a distinct edge. ESRI
provides the ARC/CAD product to compete in this arena, but MGE is
a CAD at its core. The data is stored in layers or covers. The
product has a built-in GUI, but it is not that easy to use (Now let's
see, which of these 500 buttons do I need to press?). MGE does come
with a bundled C-language interface, which I consider important.
1B. ARC/Info architecture: ARC is also stored as covers. It is much
more concerned with "topographical-correctness" than MGE. For example,
when I move MGE data to ARC, ARC will find and gripe about edges that
don't match, polygons that don't close, centroids that are missing, etc..
MGE never finds anything wrong with cleaned ARC data. If the planned
geo-system is to be used for cartographic or polygonal study, then
ARC would be a better choice. ARC/Info is command-line driven. You
can build your own GUI, using the bundled ARCTools package as your
prototype or you can just use the ARCTools as is. Eventually though,
(if you are the programmer) you're going to have to learn those zillion
command names. ARC/Info does NOT come with a 'C' interface; you must
use their own AML language. I consider this a minus.
From: Bryant Ralston <email@example.com>
I have worked with both and it really begins with the data structure
of both packages. MGE is built on top of a CAD data model while ARC/INFO's
data structure was built from the ground up as a topoligcal data structure.
Therefore, ARC/INFO really was designed as a GIS while MGE was a CAD-program
(Microstation) with a GIS toolbox grafted onto it. As a result, MGE requires
more 'hands-on' managing of the associated databases while ARC/INFO manages
the database for you. I personally am a geographer and consider myself more
of a GIS user than a CAD user although I started in CAD design with AutoCAD.
Now ESRI has an ArcCAD package similiar in nature to MGE but built on
top of AutoCAD. Beware though to introductory GIS users or former AutoCAD
users ArcCAD can be very confusing.
All in all, to compare ARC/INFO to MGE really depends on what you want
out of your GIS system and the amount of data you have and the form
you have it in now. If you are a traditional Microstation user and have
lots of design files then MGE is probably for you but be careful when you
want to use ARC coverages because the attribute linkages do not translate
very well. With ARC/INFO rev 7.02, they are supposed to be able to export
RIS linkages for use in MGE but I haven't tried it yet.
End of FAQ
(C) 1994, 1995, 1996 Lisa Nyman. This document may be distributed freely
provided this copyright notice is included. Permission is not granted
for commercial use. The mention of product trade names in no way endorses
these products or the companies which develop and distribute them.
Also, this document represents collective knowledge of many people.
The editors, any government, or business are not responsible for
errors in the content. Your mileage may vary. Any prices mentioned
are of course subject to change.
Lisa W. Nyman <firstname.lastname@example.org> |Standard Disclaimer: |In Karate one|
------------------------------------ |I speak for me, not U.S.|does not make|
Personal email: email@example.com|________________________|the first |
GIS FAQ: http://www.census.gov/geo/www/faq-index.html |move. |