VanLUG Email Archive
Dave Michelson (dmichelson@home.com)
Wed, 05 May 1999 18:38:02 -0700
Andrew Daviel wrote:
>
> Thanks!
>
> There are some GIS data sets for Canada somewhere - can things like GRASS,
> drawmap import this data (probably arc/info - ASCII readable if only one
> knows what the format it...) ?
There are *so* many GIS data formats, it's incredible. Most of these
tools have lots of input filters but one almost always has to check
first to be sure that the software is compatible with the data (or vice
versa).
In the US, the USGS provides literally scads of freely available DEM and
LULC data through their web site, http://www.usgs.gov/. In the recent
past, they supplied the data in formats unique to each product but have
recently moved to a "universal" format called SDTS (Spatial Data
Transfer Standard). Designed by committee, it's very complicated and
has earned a reputation for being a real nightmare to deal with.
Support is improving all the time, though.
Elsewhere in the world, governments tend to hoard GIS data and charge
large sums for it. Natural Resources Canada maintains the National
Topographic Data Base (NTDB). It covers the entire Canadian landmass
and contains the features normally found on topographic maps at the
scales of 1:50 000 and 1:250 000. They charge $$$ for the data, but per
byte, not per mapsheet. See
http://www.ccg.nrcan.gc.ca/ext/html/english/products/ntdb/ntdb.html
for details.
British Columbia maintains a terrain database with even higher
resolution (1:20 000) called the
Terrain Resource Information Management (TRIM) System. Each mapsheet is
precisely 12 minutes of longitude wide by 6 minutes of latitude high and
costs $600 per set of files. See
http://www.env.gov.bc.ca/gdbc/trim.htm
for details.
In any case, the above URL's will point you towards info concerning the
formats in which each data set is available while the URL's for each
package (under http://SAL.KachinaTech.COM/E/6/E6.shtml) will point you
towards info concerning the formats which each package can handle.
Good luck!
-- Dave Michelson dmichelson@home.com
This archive was generated by hypermail 2.0b3 on Wed 05 May 1999 - 18:44:12 PDT