PolygonClassStatistics - 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 Name | Parameter Type |
|---|---|---|
| in | InputImage | Input image |
| mask | InputMask | Input image |
| vec | Input vectors | Input File name |
| out | Output Statistics | Output File name |
| field | Field Name | List |
| layer | Layer Index | Int |
| elev | Elevation management | Group |
| elev.dem | DEM directory | Directory |
| elev.geoid | Geoid File | Input File name |
| elev.default | Default elevation | Float |
| ram | Available RAM (Mb) | Int |
| inxml | Load otb application from xml file | XML input parameters file |
| outxml | Save otb application to xml 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.
[Elevation management]: This group of parameters allows managing elevation values. Supported formats are SRTM, DTED or any geotiff. DownloadSRTMTiles application could be a useful tool to list/download tiles related to a product.
- DEM directory: This parameter allows selecting a directory containing Digital Elevation Model files. Note that this directory should contain only DEM files. Unexpected behaviour might occurs if other images are found in this directory.
- Geoid File: Use a geoid grid to get the height above the ellipsoid in case there is no DEM available, no coverage for some points or pixels with no_data in the DEM tiles. A version of the geoid can be found on the OTB website (http://hg.orfeo-toolbox.org/OTB-Data/raw-file/404aa6e4b3e0/Input/DEM/egm96.grd).
- Default elevation: This parameter allows setting the default height above ellipsoid when there is no DEM available, no coverage for some points or pixels with no_data in the DEM tiles, and no geoid file has been set. This is also used by some application as an average elevation value.
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")
# The following line execute the application
PolygonClassStatistics.ExecuteAndWriteOutput()
Limitations¶
None
Authors¶
This application has been written by OTB-Team.