SampleExtraction - Sample Extraction
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Extracts samples values from an image.

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

The application extracts samples values from animage using positions contained in a vector data file. 

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 *SampleExtraction* .

.. [#] Table: Parameters table for Sample Extraction.

+--------------------+---------------------------------------+--------------------------+
|Parameter Key       |Parameter Name                         |Parameter Type            |
+====================+=======================================+==========================+
|in                  |InputImage                             |Input image               |
+--------------------+---------------------------------------+--------------------------+
|vec                 |Input sampling positions               |Input File name           |
+--------------------+---------------------------------------+--------------------------+
|out                 |Output samples                         |Output File name          |
+--------------------+---------------------------------------+--------------------------+
|outfield            |Output field names                     |Choices                   |
+--------------------+---------------------------------------+--------------------------+
|outfield prefix     |Use a prefix and an incremental counter| *Choice*                 |
+--------------------+---------------------------------------+--------------------------+
|outfield list       |Use the given name list                | *Choice*                 |
+--------------------+---------------------------------------+--------------------------+
|outfield.prefix.name|Output field prefix                    |String                    |
+--------------------+---------------------------------------+--------------------------+
|outfield.list.names |Output field names                     |String list               |
+--------------------+---------------------------------------+--------------------------+
|field               |Field Name                             |List                      |
+--------------------+---------------------------------------+--------------------------+
|layer               |Layer Index                            |Int                       |
+--------------------+---------------------------------------+--------------------------+
|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.

**Input sampling positions**: Vector data file containing samplingpositions. (OGR format).

**Output samples**: Output vector data file storing samplevalues (OGR format). If not given, the input vector data file is updated.

**Output field names**: Choice between naming method for output fields. Available choices are: 

- **Use a prefix and an incremental counter**: Use a prefix and an incremental counter.

 * **Output field prefix**: Prefix used to form the field names thatwill contain the extracted values.

- **Use the given name list**: Use the given name list.

 * **Output field names**: Full list of output field names.


**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_SampleExtraction -in support_image.tif -vec sample_positions.sqlite -outfield prefix -outfield.prefix.name band_ -field label -out sample_values.sqlite

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

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

	SampleExtraction.SetParameterString("vec", "sample_positions.sqlite")

	SampleExtraction.SetParameterString("outfield","prefix")

	SampleExtraction.SetParameterString("outfield.prefix.name", "band_")

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

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

None

Authors
~~~~~~~

This application has been written by OTB-Team.