[GRASS5] Re: An internal db for GRASS
grass5 at geog.uni-hannover.de
Sat, 10 Feb 2001 12:23:35 -0800 (PST)
On Sat, 10 Feb 2001, Roger S. Miller wrote:
> Forgive my ignorance, but...
Welcome to my club! :-)
> Postgres handles geometric data -- points, circles, polylines, polygons
> and so on -- and includes functions to determine if a point is in an
> area, two lines intersect and others (but no sort of raster
> functionality). How different is that from handling spacial data
> structures? Are those structures something that for some reason
> couldn't be addressed as a user-defined type?
I know it does. When I brought this up months ago, I was told by those who
I assume know much better than I, that it was not suitable for an arc-node
format such as GRASS.
Thinking about this just now, it occurs to me that we'd use points and
arcs as graphic types. The problem is that postgres does not handle
topology. What it would take to handle topology within postgres, GRASS or a
separate (but tightly integrated) program is beyond my knowledge.
Looking at ARC/Info export data, I see that vectors have attributes such
as LPOLY, RPOLY and so on. Is this computationally too difficult to store in
a postgres database along with each spatial arc or point? I don't know.
Sure, raster data is handled well internally and we don't want/need to
mess with that. But, multi-attribute sites data and vector data are a
I have a bunch of questions directly related to this point, but that'll be
the subject of a separate message later today.
> I was of the impression that Postgres was under a Berkeley license, not
> GPL. Is the distinction significant?
It was a while since I looked at the postgres license, so I just did. Here
Portions Copyright (c) 1996-2000, PostgreSQL, Inc
Portions Copyright (c) 1994 Regents of the University of California
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose, without fee, and without a written agreement
is hereby granted, provided that the above copyright notice and this
paragraph and the following two paragraphs appear in all copies.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
The third paragraph says it all. So, it's not GPL, but it can be used and
distributed without restriction, either as part of the GRASS distribution or
if we tell folks, "get your own copy". It's also not the usual BSD license,
either. I'm not a lawyer, but this looks quite unrestrictive to me.
Dr. Richard B. Shepard, President
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