v.buildgrass - Online in the Cloud

PROGRAM:

NAME

v.build - Creates topology for vector map.
Optionally also checks for topological errors.

KEYWORDS

vector, topology, geometry

SYNOPSIS

v.build
v.build --help
v.build [-e] map=name [error=name] option=string[,string,...] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]

Flags:
-e
Extensive checks for topological errors
Perform in-depth checks for topological errors when building topology

--overwrite
Allow output files to overwrite existing files

--help
Print usage summary

--verbose
Verbose module output

--quiet
Quiet module output

--ui
Force launching GUI dialog

Parameters:
map=name [required]
Name of vector map

error=name
Name for output vector map where erroneous vector features are written to

option=string[,string,...] [required]
Build topology or dump topology or indeces to standard output
Options: build, dump, sdump, cdump, fdump
Default: build
build: build topology
dump: write topology to stdout
sdump: write spatial index to stdout
cdump: write category index to stdout
fdump: write feature index to stdout (OGR simple-feature-based formats only)

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 indeces, 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

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