ZonalStatistics

This application computes zonal statistics

Description

This application computes zonal statistics from label image, or vector data. The application inputs one input multiband image, and another input for zones definition. Zones can be defined with a label image (inzone.labelimage.in) or a vector data layer (inzone.vector.in). The following statistics are computed over each zones: mean, min, max, and standard deviation. Statistics can be exported in a vector layer (if the input zone definition is a label image, it will be vectorized) or in a XML file

This application has several output images and supports “multi-writing”. Instead of computing and writing each image independently, the streamed image blocks are written in a synchronous way for each output. The output images will be computed strip by strip, using the available RAM to compute the strip size, and a user defined streaming mode can be specified using the streaming extended filenames (type, mode and value). Note that multi-writing can be disabled using the multi-write extended filename option: &multiwrite=false, in this case the output images will be written one by one. Note that multi-writing is not supported for MPI writers.

Parameters

Input Image -in image Mandatory

Background value to ignore in statistics computation -inbv float

Type of input for the zone definitions -inzone [vector|labelimage] Default value: vector

  • Input objects from vector data
  • Input objects from label image

Input objects from vector data options

Input vector data -inzone.vector.in vectorfile Mandatory

Reproject the input vector -inzone.vector.reproject bool Default value: false

Input objects from label image options

Input label image -inzone.labelimage.in image Mandatory

No-data value for the input label image -inzone.labelimage.nodata int

Format of the output stats -out [vector|xml|raster] Default value: vector

  • Output vector data
  • Output XML file
  • Output raster image

Output vector data options

Filename for the output vector data -out.vector.filename vectorfile Mandatory

Output XML file options

Filename for the output xml file -out.xml.filename string Mandatory

Output raster image options

File name for the raster image -out.raster.filename image [dtype] Mandatory

Background value for the output raster -out.raster.bv float

Available RAM (MB) -ram int Default value: 256
Available memory for processing (in MB).

Examples

From the command-line:

otbcli_ZonalStatistics -in input.tif -inzone.vector.in myvector.shp -out.vector.filename myvector_with_stats.shp

From Python:

import otbApplication

app = otbApplication.Registry.CreateApplication("ZonalStatistics")

app.SetParameterString("in", "input.tif")
app.SetParameterString("inzone.vector.in", "myvector.shp")
app.SetParameterString("out.vector.filename", "myvector_with_stats.shp")

app.ExecuteAndWriteOutput()

Limitations

  1. The inzone.vector.in must fit in memory (if “inzone” is “vector”). 2) The vectorized label image must also fit in memory (if “out” is “vector”): if not, consider using “out” to “xml”