Polygon Class Statistics

Computes statistics on a training polygon set.

Detailed description

The application processes a set of geometries intended for training (they should have a field giving the associated class). The geometries are analysed against a support image to compute statistics :

• number of samples per class
• number of samples per geometry

An optional raster mask can be used to discard samples. Different types of geometry are supported

: polygons, lines, points. The behaviour is different for each type of geometry :

• polygon: select pixels whose center is inside the polygon
• lines : select pixels intersecting the line
• points : select closest pixel to the point

Parameters

This section describes in details the parameters available for this application. Table [1] presents a summary of these parameters and the parameters keys to be used in command-line and programming languages. Application key is PolygonClassStatistics .

[1]	Table: Parameters table for Polygon Class Statistics.

Parameter Key	Parameter Type	Parameter Description
in	Input image	Input image
mask	Input image	Input image
vec	Input File name	Input File name
out	Output File name	Output File name
field	String	String
layer	Int	Int
ram	Int	Int
inxml	XML input parameters file	XML input parameters file
outxml	XML output parameters file	XML output parameters file

• InputImage: Support image that will be classified.
• InputMask: Validity mask (only pixels corresponding to a mask value greater than 0 will be used for statistics).
• Input vectors: Input geometries to analyse.
• Output Statistics: Output file to store statistics (XML format).
• Field Name: Name of the field carrying the class name in the input vectors.
• Layer Index: Layer index to read in the input vector file.
• Available RAM (Mb): Available memory for processing (in MB).
• Load otb application from xml file: Load otb application from xml file.
• Save otb application to xml file: Save otb application to xml file.

Example

To run this example in command-line, use the following:

otbcli_PolygonClassStatistics -in support_image.tif -vec variousVectors.sqlite -field label -out polygonStat.xml

To run this example from Python, use the following code snippet:

#!/usr/bin/python

# Import the otb applications package
import otbApplication

# The following line creates an instance of the PolygonClassStatistics application
PolygonClassStatistics = otbApplication.Registry.CreateApplication("PolygonClassStatistics")

# The following lines set all the application parameters:
PolygonClassStatistics.SetParameterString("in", "support_image.tif")

PolygonClassStatistics.SetParameterString("vec", "variousVectors.sqlite")

PolygonClassStatistics.SetParameterString("field", "label")

PolygonClassStatistics.SetParameterString("out", "polygonStat.xml")

# The following line execute the application
PolygonClassStatistics.ExecuteAndWriteOutput()

Limitations

None

Authors

This application has been written by OTB-Team.