Supervised classification (Tutorial)

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(Train image classifier)
(Training of per-pixel classifier)
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* Type into the search box of the Windows taskbar: {{typed|text=mapla.bat}}. Click on mapla.bat to open  Monteverdi Application Launcher.
 
* Type into the search box of the Windows taskbar: {{typed|text=mapla.bat}}. Click on mapla.bat to open  Monteverdi Application Launcher.
 
* In the search engine of mapla, type {{typed|text=TrainImages}} and double click '''TrainImagesClassifer'''.
 
* In the search engine of mapla, type {{typed|text=TrainImages}} and double click '''TrainImagesClassifer'''.
* Specify a multispectral image as Input Image: the Sentinel-2 image ''Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif ''
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* In the {{button|text=Input Image List}} specify one (or several) multispectral image: ''Subset_S2A_MSIL2A_20170619T_MUL.tif ''.
* Specify directory and name for the XML Output image. Specify the extension '''.xml''' for this file.
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* In the {{button|text=Input Vector List}} choose a vector polygon file with training areas.  
* (see figure '''B''').
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* Set ''Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif'' as {{button|text=Input image list}}.
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* Set ''lab07_training_input.shp'' as {{button|text=Input vector list}}.
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* Set ''Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif.xml'' as {{button|text=Input XML image statistics file}}.
 
* Set ''Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif.xml'' as {{button|text=Input XML image statistics file}}.
 
* Set {{button|text=Name of discrimination field}} to ''C_ID'' (C_ID refers to the column that contains the LUC code).
 
* Set {{button|text=Name of discrimination field}} to ''C_ID'' (C_ID refers to the column that contains the LUC code).

Revision as of 17:34, 8 December 2018

Contents

Classification with Orfeo Toolbox

Training of per-pixel classifier

  • 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 specify one (or several) multispectral image: Subset_S2A_MSIL2A_20170619T_MUL.tif .
  • In the Input Vector List choose a vector polygon file with training areas.
  • Set Subset_S2A_MSIL2A_20170619T_MUL_BOA.tif.xml as Input XML image statistics file.
  • Set Name of discrimination field to C_ID (C_ID refers to the column that contains the LUC code).
  • Save the Output confusion matrix as ConfusionMatrixSVM.csv.
  • Save the Output model as SVM.model.
  • Click on Execute.
  • Calculation of accuracies :
    Open ConfusionMatrixSVM.csv in LibreOffice or MS Excel and calculate overall, producer and consumer accuracies.

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.
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