Definiens Developer 7 - PCI Geomatics

Definiens Developer 7 - Reference Book3 Algorithms ReferenceSee chessboard segmentation reference.Input ParametersThese parameters are identical for the first and the second layer.ChessboardSegmentation on page 15LayerChoose the image layer to analyze form the drop-down menu. Use todisable one of the two filters. If you select , then the following parameterswill be inactive.Scale 1-4You can define several scales to be analyzed at the same time. If at least one scale istested positive, the pixel will be classified as image object.By default, no scale is used what is indicated by a scale value of 0. To define a scale, editthe scale value.The scale value n defines a frame with a side length of 2d' with d := {all pixels withdistance to the current pixel ≤ |n|*2+1 but > (|n|-2)*2+1} with the current pixel in itscenter. The mean value of the pixels inside this frame is compared with the mean valueof the pixels inside a cube with a side length of 2d' with d' := {all pixels with distance tothe current pixel ≤ (|n|-2)*2+1 but not the pixel itself}. In case of |n|≤3 it is just the pixelvalue.Figure 8: Scale testing of the contrast filter segmentation.Select a positive scale value to find objects that are brighter than their surroundings onthe given scale. Select a negative scale value to find objects that are darker than theirsurroundings on the given scale.GradientUse additional minimum gradient criterion for objects. Using gradients can increase thecomputing time the algorithm. Set this parameter to 0 to disable the gradient criterion.Lower ThresholdPixels with layer intensity below this threshold will be assigned to the ignored bythreshold class.Upper ThresholdPixels with layer intensity above this threshold will be assigned to the ignored bythreshold class.26