DESCRIPTION
v.build builds support files for GRASS vector maps. These
support files supply topology and category information including
spatial index that are needed by other GRASS modules.
GRASS is generating these support files automatically, only in rare
cases the user has to (re)build them.
Refer to
vector data processing in GRASS GIS for
more information on GRASS vector data model.
NOTES
v.build creates support files only for vector maps located in
the user's current mapset. It's not possible to rebuild support files
(option=build) for vector maps from other mapsets.
In case of errors, the user can optionally generate an error
vector map containing the erroneous vectors for later inspection.
If error vector map is specified, v.build checks:
- isolated bondaries (which are not forming any areas),
- centroids outside of area,
- duplicated centroids.
Extensive checks for topological errors (flag -e) also
includes:
- lines or boundaries of zero length,
- intersecting boundaries, ie. overlapping areas,
- areas without centroids that are not isles.
EXAMPLES
Build topology
Note that option=build recreates also spatial and category
indices, not only topology. For linked OGR layers
(see v.external) also feature
index is created.
v.build map=urbanarea option=build
Note that the vector map urbanarea must be located in the
current mapset.
Dump topology or indices
Dump options print topology, spatial, category or feature index to
standard output. Such information can be printed also for vector maps
from other mapsets. A description of the vector topology is available in
the GRASS GIS 7 Programmer's Manual,
section "Vector library topology management".
v.build map=urbanarea option=dump
SEE ALSO
v.build.all,
v.build.polylines,
v.edit,
v.split
See also wxGUI vector digitizer.
AUTHORS
Dave Gerdes, U.S.Army Construction Engineering Research
Laboratory,
Michael Higgins, U.S.Army Construction Engineering Research Laboratory,
Radim Blazek, ITC-irst, Trento, Italy
Last changed: $Date$