NAME
v.rast.bufferstats - Calculates statistics of raster map(s) for buffers around vector geometries.
KEYWORDS
vector,
raster,
buffer,
statistics
SYNOPSIS
v.rast.bufferstats
v.rast.bufferstats --help
v.rast.bufferstats [-tpurl] input=name raster=name[,name,...] buffers=integer[,integer,...] type=string[,string,...] [layer=string] column_prefix=string[,string,...] [methods=string[,string,...]] [percentile=integer] [output=name] [separator=character] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -t
- Tabulate area within buffers for categories in raster map(s)
- -p
- Used with -t flag will return percentage of area for categories
- -u
- Update columns if they already exist
- -r
- Remove columns without data
- -l
- Use labels for column names if possible
- --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:
- input=name [required]
- Name of input vector map
- Vector map containing geometries to compute buffer statistics for
- raster=name[,name,...] [required]
- Raster map(s) to calculate statistics from
- buffers=integer[,integer,...] [required]
- Buffer distance(s) in map units
- type=string[,string,...] [required]
- Vector type to work on
- Options: points, lines, areas
- Default: points,lines,areas
- layer=string
- Layer number or name
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 1
- column_prefix=string[,string,...] [required]
- Column prefix for new attribute columns
- methods=string[,string,...]
- The methods to use
- Options: number, number_null, minimum, maximum, range, sum, average, average_abs, stddev, variance, coeff_var, first_quartile, median, third_quartile
- Default: number,number_null,minimum,maximum,range,sum,average,average_abs,stddev,variance,coeff_var,first_quartile,median,third_quartile
- percentile=integer
- Percentile to calculate
- Options: 0-100
- output=name
- Name for output file (if "-" output to stdout)
- separator=character
- Field separator
- Field separator in output file
- Default: |
The purpose of the
v.rast.bufferstats module is to provide
local environmental context to a series of input geometries.
It computes statistics from multiple input raster maps within multiple
buffers around selected geometries in the input vector map.
Available statistics are either
- statistics provided by r.univar or
- if the t-flag is checked - area of, number of and/or the most frequent (mode) raster categories
within the buffers using r.stats.
If the output option is specified, results are written to a text
file or stdout instead of the attribute table of the input map.
The output file is produced with the following column order:
cat | prefix | buffer| statistic/measure | value
separated by the user defined separator (default is |).
The module temporarily modifies the computational region. The region is set to the
extent of the respective buffers, while the alignment of the current region is kept.
# Preparations
g.region -p raster=elevation,geology_30m
v.clip -r input=bridges output=bridges_wake
# Tabulate area of land cover map
g.region -p raster=elevation,geology_30m align=geology_30m
v.rast.bufferstats -t input=bridges_wake raster=geology_30m buffers=100,250,500 column_prefix=geology
# Compute terrain statistics and update vector attribute table
g.region -p raster=elevation,geology_30m align=elevation
r.slope.aspect elevation=elevation slope=slope aspect=aspect
v.rast.bufferstats input=bridges_wake raster=altitude,slope,aspect buffers=100,250,500 column_prefix=altitude,slope,aspect methods=minimum,maximum,average,stddev percentile=5,95
In order to avoid topological issues with overlapping buffers, the module loops over the
input geometries. However, this comes at costs with regards to performance.
For a larger number of geometries in the vector map, it can be therefore more appropriate to
compute neighborhood statistics with
r.neighbors and to extract (
v.what.rast,
r.what) or aggregate (
v.rast.stats) from those maps with neighborhood statistics.
The module is affected by the following underlying library issue:
Currently, the module uses GRASS native buffering through pygrass which should be replaced by buffering using GEOS:
https://trac.osgeo.org/grass/ticket/3628
r.univar
r.stats
v.rast.stats
Stefan Blumentrath, Norwegian Institute for Nature Research, Oslo, Norway
SOURCE CODE
Available at:
v.rast.bufferstats source code
(history)
Latest change: Tuesday Mar 26 20:41:36 2024 in commit: 3b09b1d78f6e96ffebacac6e36f0afd91ad0c091
Main index |
Vector index |
Topics index |
Keywords index |
Graphical index |
Full index
© 2003-2024
GRASS Development Team,
GRASS GIS 8.4.1dev Reference Manual