Class SoZeroCrossingsProcessing2d

  • All Implemented Interfaces:

    public class SoZeroCrossingsProcessing2d
    extends SoImageVizEngine
    SoZeroCrossingsProcessing2d engine. For an introduction to edge marking, see section Introduction to Edge Marking.

    Zero-crossings are points where the Laplacian switches from positive to negative values, and vice versa.

    A simple zero-crossing detection is obtained by thresholding the Laplacian to retain positive intensities, then detecting the boundaries of the binary image, as in Figure 1. Such zero-crossing points are not precisely located.

    Figure 1: Thresholding a laplacian to determine the zero crossings ZERO-CROSSINGS is even better to mark a point if the laplacian changes its sign in its 3x3 neighbourhood, and if the laplacian magnitude is smaller than all magnitudes in that neighbourhood, as in Figure 2.

    Figure 2: Zero-crossing a laplacian Compared to thresholding of a gradient, zero-crossings have the advantage of producing closed curves of 1 pixel thickness. This is most interesting when precise object boundary detection is the goal.

    File format/default:

    ZeroCrossingsProcessing2d {

      inImage NULL

    Library references: zero_crossings

    • Constructor Detail

      • SoZeroCrossingsProcessing2d

        public SoZeroCrossingsProcessing2d()