Madagascar2011 - 10 - OTB Object Based Image Analysis

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Madagascar2011 - 10 - OTB Object Based Image Analysis

  1. 1. Orfeo ToolboxObjects detection Stéphane MAYstephane.may@cnes.fr orfeo-toolbox.org 1
  2. 2. Objects detectionType of objects searched Buildings Roads Rivers Tents Boats, planes Etc. orfeo-toolbox.org 2
  3. 3. Objects detectionMultiples approaches Radiometry (if the object has a homogenous specific radiometry) ➢ Thresholds on radiometry values ➢ Spectral angle Textures and contours ➢ Local correlation, local mutal information Contours ➢ HOG (Histogram of Gradient) Segments (radiometry + contours) ➢ Computation of segments features and selection with SVM for example orfeo-toolbox.org 3
  4. 4. Use case 1 : objects detectionMenu File > Open ./output_fus1.tifMenu Filtering > Feature extraction Original data Angle spectral on 1 point of the object Angle spectral on 2nd point of the object Others as you wantMenu Filtering > Band Math if(min(im1b2, im1b3)<0.15,im1b1,0) Try yours... orfeo-toolbox.org 4
  5. 5. Use case 2 : connected component segmentation (1/3) Menu File > Open ./output_fus1.tif Menu Filtering > Connected Segmentation Module Mask Formulas ➢ ndvi(b3,b4)<0.5 ➢ (b1>300) * (b2 >400) Display : Mask output. Click on Update. Display : Masked image. Click on Update. Connected component formulas ➢ distance < 100 (Distance between adjacent pixels is less than 100) ➢ (p1b1>300) * (p1b2 >200) Display : Segmentation output. Click on Update. orfeo-toolbox.org 5
  6. 6. Use case 2 : connected component segmentation (2/3) Objects min area 10 30 Display : Relabelling with small objects. Click on Update. Object analysis formula ➢ (SHAPE_RegionRatio > 0.4) and (SHAPE_SizeOnBorder==0) Display : Filter output. Click on Update. In the viewer, right click on a segment : features are printed in the main window => Now try your formulas ! orfeo-toolbox.org 6
  7. 7. Use case 2 : connected component segmentation (3/3)Menu visualization > Viewer Raster : reader0 Vector data to display : OuputVectorDataOutputVectorData Right click > Export dataset houses.shp (shapefile->SIG) orfeo-toolbox.org 7
  8. 8. Connected component segmentation orfeo-toolbox.org 8
  9. 9. Use case 3 : object labelling (1/2)Menu File > Open ./output_fus1.tifMenu Filtering > Mean shift module Spatial radius : 5, Spectral value : 30, Min region : 50Menu learning > Object labelling Image to classify : Reader0 Labeled Image : MeanShift->LabeledImage Add 1 class for object. Right click on twice on segments to select them. Add 2nd class for non object. Right click on twice on segments to select them. Tab Learning. Classify. orfeo-toolbox.org 9
  10. 10. Use case 3 : object labelling (2/2)Tab Objects. ➢ Click on Sample (list of segments ID with features near the threshold of SVM classification) ➢ Select one segment ID. Select the other class. Right click to redefine.Tab Learning. Classify.Save/quit orfeo-toolbox.org 10
  11. 11. Object labelling (1/5) orfeo-toolbox.org 11
  12. 12. Object labelling (2/5) orfeo-toolbox.org 12
  13. 13. Object labelling (3/5) orfeo-toolbox.org 13
  14. 14. Object labelling (4/5) orfeo-toolbox.org 14
  15. 15. Object labelling (5/5) orfeo-toolbox.org 15
  16. 16. MonteverdiThank you for your attention ! orfeo-toolbox.org 16

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