ENH update readme

(cherry picked from commit b88d92d)

python/plugins/processing/algs/otb/maintenance/README

@@ -1,11 +1,64 @@
+Requirements
+============
 
-Requirement
-1) qgis
-2) sextante_taudem (TauDEM-1.1.1.zip)
-3) sextante (sextante-1.0.9.zip)
-4) PYTHONPATH=.:/usr/lib/otb/python:/usr/share/qgis/python/plugins:~/.qgis2/python/plugins
-5) ITK_AUTOLOAD_PATH=/usr/lib/otb/applications 
+QGIS
+----
+Python plugins
+--------------
+Set OTB environment
+--------------------
+
+export PYTHONPATH=/path/to/OTB/install/lib/otb/python/:$PYTHONPATH
+# Environment variable for old OTB versions
+export ITK_AUTOLOAD_PATH=/path/to/OTB/install/lib/otb/applications/
+# Environment variable for new OTB versions
+export OTB_APPLICATION_PATH=/path/to/OTB/install/lib/otb/applications/
+# Set LD_LIBRARY_PATH
+export LD_LIBRARY_PATH=/path/to/OTB/install/lib/:$LD_LIBRARY_PATH
+
+Set QGIS environment
+---------------------
+export PYTHONPATH=:/usr/share/qgis/python/plugins:~/.qgis2/python/plugins:$PYTHONPATH
+# Set LD_LIBRARY_PATH
+export LD_LIBRARY_PATH=/path/to/QGIS/install/lib/:$LD_LIBRARY_PATH
+# Add maintenance folder to python path
+export PYTHONPATH=/path/to/QGIS/src/python/plugins/processing/algs/otb/maintenance:$PYTHONPATH
+
+Check the white and black list for the current OTB version
+----------------------------------------------------------
+In the maintenance directory, the OTB applications are split in two files black_list.xml and white_list.xml.
+These files are organized as follows :
+For each OTB version, a new node version with id as attribute is added to the node data.
+Each application is then added in the node app_name.
+```xml
+<?xml version="1.0"?>
+<data>
+    <version id="3.16">
+        <app_name>BinaryMorphologicalOperation</app_name>
+        <app_name>EdgeExtraction</app_name>
+        <app_name>GrayScaleMorphologicalOperation</app_name>
+        <app_name>DimensionalityReduction</app_name>
+        <app_name>Pansharpening</app_name>
+        <app_name>ExtractROI</app_name>
+        <app_name>RigidTransformResample</app_name>
+        <app_name>Segmentation</app_name>
+        <app_name>KMeansClassification</app_name>
+        <app_name>TrainSVMImagesClassifier</app_name>
+        <app_name>ComputeConfusionMatrix</app_name>
+        <app_name>OpticalCalibration</app_name>
+        <app_name>SarRadiometricCalibration</app_name>
+        <app_name>Smoothing</app_name>
+    </version>
+</data>
+```
+The list of available applications for each version is not fixed.
+
+OTBSpecific_XMLcreation.py
+--------------------------
+Warning : Some of the applications needs to be split to be user-friendly. Here comes the file OTBSpecific_XMLcreation.py. 
+Each function follows the pattern getNameOfTheOTBApplication().
 
 Creating xml files
-cd .qgis2/python/plugin/sextante/otb/maintenance
+------------------
+cd /path/to/QGIS/src/python/plugins/processing/algs/otb/maintenance
 python ./OTBHelper.py