On 15/05/09 12:23, achim wrote:
Hello folks,
I wonder, how you deal with vector-data. I am really not happy with it,
even with help from qgis. Do I have to go deep into PostGis (which does
not support topology, as far as I know) to make some more or less
advanced working steps like selecting areas, which intersect with
another,
v.select. In grass 6.x it only provides the option "overlap", but in grass7, you get the full GEOS set, i.e.: equals, disjoint, intersects, touches, crosses, within, contains, overlaps, relates.
combine line vector layers and break on intersections
v.patch + v.clean
, measure
length of lines even in an latlong projection...
v.to.db, although I'm not 100% sure how that deals with lat-long. Only comment in the man page:
"When calculating perimeters in Latitude-Longitude locations, the geodesic distance between the vertices is used."
I would suppose that this is the same for line length...
Any hints for dealing with vector data in fossgis are welcome.
You have tons of options. GRASS has a very advanced vector engine and you should be able to do most of what you need, once you get used to it.
Start by reading this:
http://grass.itc.it/grass64/manuals/html64_user/vectorintro.html
Moritz