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Archive-name: geography/infosystems-faq
Posting-Frequency: monthly
Last-modified: 1997/03/13
URLs: ftp://ftp.census.gov/pub/geo/gis-faq.txt
ftp://abraxas.adelphi.edu/pub/gis/FAQ
http://www.census.gov/geo/www/faq-index.html
(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. Administration:
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
there?
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
information?
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
one?
9. Is there a package available to convert from UTM to
latitude/longitude?
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?
5. Technobits:
1. What are some algorithms for calculating the distance between
2 points?
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?
Netiquette
----------
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
question 1)
If you have information that you think should be included in the FAQ,
please e-mail the information to Lisa Nyman .
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
goes away.
________________________________
Q1.1: How do I get the FAQ list?
The most current version is available
via anonymous FTP on
ftp://ftp.census.gov/pub/geo/gis-faq.txt
ftp://abraxas.adelphi.edu/gis/FAQ
Use your favorite WWW browser and take a peek at:
http://www.census.gov/geo/www/faq-index.html
To get the FAQ in plain text (mail message > 100K), send a mail message to
gis-faq-request@abraxas.adelphi.edu
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
lnyman@census.gov
______________________________________________________________________
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
apply:
(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
______________________________________________________________________
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
Willmott, 1989)
GIS are simultaneously the telescope, the microscope, the computer, and
the xerox machine of regional analysis and synthesis of spatial data.
(Abler, 1988)
From: David Mark
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: dmarble@magnus.acs.ohio-state.edu (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
Education.
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
contact.
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
lab facilities.
Contact the AAG, 1710 16th Str NW, Washington DC 20009-3198 for
ordering information. AAG phone: 202-234-1450 Email: guide@aag.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
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
ftp site.
ftp address:
ftp.ncgia.ucsb.edu
WWW address:
http://www.ncgia.ucsb.edu
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
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
forms:
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
processors.
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
law.
We wish to acknowledge the generous support of ESRI which has
contributed significantly to the start-up of this activity.
*********
Materials Available
There are several ASCII files located in the /ftp/biblio area.
These contain:
(A) A complete description of the Master Bibliography
project.
(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
EndNote)
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
GIS)
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-
Note)
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
publishers.
To access the currently available files enter the following
commands:
ftp 128.146.209.34 (this is BASTET@SBS.OHIO-STATE.EDU)
when you are asked to log in, respond with the user name of
anonymous
when you are asked for a password, please respond with your
Internet address.
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
here)
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
shortly.
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
http://thoth.sbs.ohio-state.edu/
______________________________________________________________________
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
that scale.
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
such testing.
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: tjmisek@hou.amoco.com (Thomas Misek)
The document that lists the format & form of the Vector Product Format
is:
Military Standard
MIL-STD-600006
30 September 1993
This 200+ page document has a complete description of the format.
[old address deleted - new address from newcomb@navo.navy.mil (Donald
R. Newcomb)]
The correct address for the public to request any MIL-STD is:
Naval Publications & Forms Center
Code 3051
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"
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
facilitating
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
ftp at:
ftp://sdts.er.usgs.gov/pub/sdts
More information on SDTS is also available by visiting the SDTS web page
located at:
http://mcmcweb.er.usgs.gov/sdts/
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 : sdts@usgs.gov
______________________________________________________________________
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
Richmond
Victoria 3121
Phone 429-9888
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
ISBN 0-940087-04-9
Ventana Press may be contacted at:
P.O. Box 2468
Chapel Hill
NC 27515
USA
Phone (919) 490-0062
Also, Virginia Hetrick, in sunny Calififornia
suggests:
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
the others.
WWW resources:
A page of links:
http://wwwis.cs.utwente.nl:8080/faase/DWG/dxf.html
Release 13 documentation in Windows Help format
with a supplementary browser to simplify searching:
http://www.cloudnet.com/~dyoung/
Release 10 documentation in text format:
ftp://ftp.cc.monash.edu.au/pub/graphics.formats/DXF.ascii.Z
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