Re: [seul-edu] Free USGS topo maps online

["Jonathan Byron" <geodigest@telocity.com>]

There are several GIS projects in the works that are GPLed or otherwise
free. Start with www.freegis.org for pointers.  GRASS is the one of the
oldest and best known free GISs - it was started by the US Army Corps of
Engineers, and then spun off to the public when the commercial GIS firms
convinced the politicians that the government had no business creating free
software that took bussiness away from the $10,000 a copy GIS vendors. GRASS
works primarily with the raster data model, and has very limited vector
support.

The topo maps that you mentioned are actually scanned images of the maps
(raster images) - they do not have the geographic information like
coordinates, projection info, or attributes built into the data except as
colors that humans interpret. It would take some work to get these maps into
a real GIS.  There are other topographic data formats that are available
free, like the Digital Line Graph, or DLG - this is a vector form where each
geometric object (like a road or contour line) has a link to a database, and
properties like the name of the road, speed limit, or elevation.  There is
less Free Software available for vector files, but look at MapServer,
Practical Map Server, and OpenMap for starters.

And yes, we do need development of better Free (TM) GIS software!!

Jonathan Byron
Assistant Professor of Geography
Jacksonville University


----- Original Message -----
From: <brk@slip.net>
To: <seul-sci@seul.org>; <seul-edu@seul.org>
Sent: Friday, April 13, 2001 11:46 AM
Subject: [seul-edu] Free USGS topo maps online


> After much searching, I finally called the USGS and was sent to this
> page for free topo maps, http://www.topowest.com/.
>
> As we chatted for a few minutes, it was determined that a GIS is needed
> to actually deciper the USGS data and create maps from it.  Is there a
> product out there or a project in progress?
>
> Mapping is useful to lots of folks, should we create something if it is
> not there yet?
>
> Bill Ries-Knight
>