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 Type            |Parameter Description                  |
+====================+==========================+=======================================+
|in                  |Input image               |Input image                            |
+--------------------+--------------------------+---------------------------------------+
|vec                 |Input File name           |Input File name                        |
+--------------------+--------------------------+---------------------------------------+
|out                 |Output File name          |Output File name                       |
+--------------------+--------------------------+---------------------------------------+
|outfield            |Choices                   |Choices                                |
+--------------------+--------------------------+---------------------------------------+
|outfield prefix     | *Choice*                 |Use a prefix and an incremental counter|
+--------------------+--------------------------+---------------------------------------+
|outfield list       | *Choice*                 |Use the given name list                |
+--------------------+--------------------------+---------------------------------------+
|outfield.prefix.name|String                    |String                                 |
+--------------------+--------------------------+---------------------------------------+
|outfield.list.names |String list               |String list                            |
+--------------------+--------------------------+---------------------------------------+
|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.

**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 classname in the input vectors. This field is copied to output.

**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_")

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

	SampleExtraction.SetParameterString("out", "sample_values.sqlite")

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

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

None

Authors
~~~~~~~

This application has been written by OTB-Team.