[GRASS5] GRASS -> SF
morten at untamo.net
Mon Feb 23 13:31:34 EST 2004
On Sat, 21 Feb 2004, Morten Hulden wrote:
> So, for me it would be very useful if I could interface the vector data in
> Postgis from both Mapserver and Grass. I use Grass alot for raster map
> generating and v.digitizing, but Grass is becoming a little 'isolated' now
> from the vector storage. Maybe there is something in 5.7 that I don't know
> about, but I haven't been able to get it to compile yet :-(
Only yesterday I managed to compile 5.7 so I got a chance to test Postgis
connectivity. (--with-nls causes errors in lib/raster/io.c, PACKAGE not
Vectors and attributes in Postgis/Postgres works fine, but areas are very,
very slow to render. As I understand it only lines and points are stored
in Postgris, but topology is rebuilt each time the monitor is redrawn.
That is bound to be slow, especially as the whole map is rebuilt, not only
the visible area.
It should be possible to make it faster, e.g. by using the Postgis BBOX
function to build only visible areas. To store full polygons in Postgis of
cause would help too, but that may not be easy to achieve. Maybe through
Retrieving full polygons is very fast, so Postgis itself is not the
problem; retrieving thousands of polygons and lines reprojecting them on
the fly takes only a few seconds in Mapserver.
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