DESCRIPTION

The v.dissolve module is used to merge adjacent areas in a vector map which share the same category value. The resulting merged area(s) retains this category value. GRASS defines a vector area as composite entity consisting of a set of closed boundaries and a centroid. The centroids must contain a category number (see v.centroids), this number is linked to area attributes and database links. Multiple attributes may be linked to a single vector entity through numbered fields referred to as layers. Refer to v.category for more details.

Merging of areas can also be accomplished using "v.extract -d" which provides some additional options. In fact, v.dissolve is simply a front-end to that module.

(GRASS Shell Script)

EXAMPLES

Basic use

v.dissolve input=undissolved output=dissolved

Dissolving based on column attributes

# check column names:
v.info -c polbnda_italy

# reclass based on desired column:
v.reclass polbnda_italy out=polbnda_italy_recl_nam col=vmap_nam

# dissolve:
v.dissove input=polbnda_italy_recl_nam output=pol_italy_regions

SEE ALSO

v.category, v.centroids, v.extract, v.reclass

AUTHORS

module: M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand
help page: Trevor Wiens

Last changed: $Date$