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Creating Lens Undistortion Maps

To calibrate camera for lens distortion an easy graphical tool can be used. The following steps must be taken:

  1. Add a UndistortImage filter to your program.
  2. Select the filter and click the "..." button by the inSpatialMap input in the Properties window. The calibration editor will open up.
  3. Set the number of rows and columns of the chessboard grid:

  4. Collect input images for the calibration process by dragging some from the image selector at the top of the window or by loading them from files.

  5. Select images which cover most of the input image area. Only images with a detected grid should be selected.

    After the selection the area coverage is computed.

  6. Click "Generate" to generate a spatial map. Check the generation quality. The calibration quality depends on the covered area and the quality of the calibration chessboard.

  7. Preview remapped images in the "Preview" tab.

Tips on generating map:

  • Try to cover at least 75% of the input image area. To get high quality results the chessboard grid should appear near all borders of the image.
  • Avoid overlapping of the chessboard grids. These point will not improve the quality but will extend computation time.
  • Put the chessboard not only at different locations, but also at different rotations.
  • Reducing the number of images will reduce computation time.
  • Always check results of remapping in the preview window. Provided invalid chessboard points can introduce a computation error, which can result in invalid calibration map.
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