DESCRIPTION allows the user to select features from a vector map by features from another one.

Supported operators (without GEOS):

Supported operators (with GEOS):


Only features with category numbers will be considered. If required the v.category module can be used to add them. Typically boundaries do not need to be given a category number, as an area's attributes are inherited from the centroid. Typically points, lines, and centroids will always want to have a cat number. E.g. take a road which separates two farms. It is ambiguous as to which farm an attribute that is attached to the road belongs to. The boundary only needs a cat number if it will hold its own attributes, such as road name or pavement form. A centroid in each paddock holds the information with respect to ownership, area, etc.


Extract fire stations (points) from urban area map (polygon) - North Carolina data set: ainput=firestations binput=urbanarea output=urban_firestations \
Extract Italian rivers from VMAP0 watercourses map: ainput=watrcrsl_eurnasia_wgs84 binput=italy_area \
         output=watrcrsl_italy operator=overlap


Processing areas with GEOS is currently incredibly slow. Significant speed-up is required.


v.category, v.overlay, v.extract

GRASS SQL interface


Radim Blazek
GEOS support by Martin Landa, Czech Technical University in Prague, Czech Republic

Last changed: $Date$