SFSTextureExtraction - SFS Texture Extraction
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Computes Structural Feature Set textures on every pixel of the input image selected channel

Detailed description
--------------------

Structural Feature Set [1] are based on the histograms of the pixels in multiple directions of the image. The SFSTextureExtraction application computes the  6 following features: SFS'Length, SFS'Width, SFS'PSI, SFS'W-Mean, SFS'Ratio and SFS'SD (Standard Deviation). The texture indices are computed from the neighborhood of each pixel. It is possible to change the length of the calculation line (spatial threshold), as well as the maximum difference between a pixel of the line and the pixel at the center of the neighborhood (spectral threshold) [2].

Parameters
----------

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

.. [#] Table: Parameters table for SFS Texture Extraction.

+------------------+----------------------------------+--------------------------+
|Parameter Key     |Parameter Name                    |Parameter Type            |
+==================+==================================+==========================+
|in                |Input Image                       |Input image               |
+------------------+----------------------------------+--------------------------+
|channel           |Selected Channel                  |Int                       |
+------------------+----------------------------------+--------------------------+
|ram               |Available RAM (Mb)                |Int                       |
+------------------+----------------------------------+--------------------------+
|parameters        |Texture feature parameters        |Group                     |
+------------------+----------------------------------+--------------------------+
|parameters.spethre|Spectral Threshold                |Float                     |
+------------------+----------------------------------+--------------------------+
|parameters.spathre|Spatial Threshold                 |Int                       |
+------------------+----------------------------------+--------------------------+
|parameters.nbdir  |Number of Direction               |Int                       |
+------------------+----------------------------------+--------------------------+
|parameters.alpha  |Alpha                             |Float                     |
+------------------+----------------------------------+--------------------------+
|parameters.maxcons|Ratio Maximum Consideration Number|Int                       |
+------------------+----------------------------------+--------------------------+
|out               |Feature Output Image              |Output image              |
+------------------+----------------------------------+--------------------------+
|inxml             |Load otb application from xml file|XML input parameters file |
+------------------+----------------------------------+--------------------------+
|outxml            |Save otb application to xml file  |XML output parameters file|
+------------------+----------------------------------+--------------------------+

**Input Image**: The input image to compute the features on.

**Selected Channel**: The selected channel index.

**Available RAM (Mb)**: Available memory for processing (in MB).

**[Texture feature parameters]**: This group of parameters allows one to define SFS texture parameters. The available texture features are SFS'Length, SFS'Width, SFS'PSI, SFS'W-Mean, SFS'Ratio and SFS'SD. They are provided in this exact order in the output image.

- **Spectral Threshold**: Spectral Threshold.
- **Spatial Threshold**: Spatial Threshold.
- **Number of Direction**: Number of Direction.
- **Alpha**: Alpha.
- **Ratio Maximum Consideration Number**: Ratio Maximum Consideration Number.

**Feature Output Image**: Output image containing the SFS texture features.

**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_SFSTextureExtraction -in qb_RoadExtract.tif -channel 1 -parameters.spethre 50.0 -parameters.spathre 100 -out SFSTextures.tif

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 SFSTextureExtraction application 
	SFSTextureExtraction = otbApplication.Registry.CreateApplication("SFSTextureExtraction")

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

	SFSTextureExtraction.SetParameterInt("channel", 1)

	SFSTextureExtraction.SetParameterFloat("parameters.spethre", 50.0)

	SFSTextureExtraction.SetParameterInt("parameters.spathre", 100)

	SFSTextureExtraction.SetParameterString("out", "SFSTextures.tif")

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

Limitations
~~~~~~~~~~~

None

Authors
~~~~~~~

This application has been written by OTB-Team.

See Also
~~~~~~~~

These additional resources can be useful for further information: 
  | [1] HUANG, Xin, ZHANG, Liangpei, et LI, Pingxiang. Classification and extraction of spatial features in urban areas using high-resolution multispectral imagery. IEEE Geoscience and Remote Sensing Letters, 2007, vol. 4, no 2, p. 260-264.
  | [2] otbSFSTexturesImageFilter class