Revision as of 18:19, 8 December 2018

Classification with Orfeo Toolbox

Training per-pixel classifiers

• Type into the search box of the Windows taskbar: mapla.bat. Click on mapla.bat to open Monteverdi Application Launcher.
• In the search engine of mapla, type TrainImages and double click TrainImagesClassifer.
• In the Input Image List click on + and select a (or optional: several) multispectral images: Subset_S2A_MSIL2A_20170619T_MUL.tif .
• In the Input Vector Data List choose a vector polygon file with training areas: lab07_training_input.shp.
• Activate the checkbox Validation Vector Data List and choose a vector polygon file with an independent sample of validation areas: lab07_validation_input.shp
• In the Output model specify an output model file: e.g. svm.model
• Activate the checkbox and save the Output confusion matrix or contingency table as ConfusionMatrixSVM.csv.
• In the Bound sample number by minimum field type 0.
• Set the training and validation sample ratio to 0. (0 = all training data).
• Set Field containing the class integer label to C_ID (C_ID refers to the column that contains the LUC code in the training and validation vector file).
• Choose LibSVM classifier from the drop down list as Classifier to use for the training.
• The SVN Kernel Type is Gaussian radial basis function.
• Switch the Parameters optimization to on.
• Set user defined seed with an integer value.
• Click on Execute.

500px

Classification

1. Open Orfeo Toolbox --> Image Classification (see figure C).
2. Set Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif as Input image.
3. Set SVM.model as Model file.
4. Set Subset_S2A_MSIL2A_20170619T_MUL_BOA.xml as Statistical file.
5. Save the Output image as su_svm.tif.
6. Evaluate classification results.
   1. Add the classification result su_svm.tif to QGIS.
   2. Right click su_svm.tif in the TOC and select Properties --> Style --> Style --> Load Style.
   3. Load lab05_MinDist.qml.

Compute a confusion matrix with independent reference data

1. Open Orfeo Toolbox --> ComputeConfusionMatrix (Vector).
2. Set su_svm.tif as Input image.
3. Set lab05_validation.shp as Input reference vector data.
4. Set Field name to C_ID.