Intensity and edge-based symmetry detection applied to car-following
We present two methods for detecting symmetry in images, one based directly on the intensity values and another one based on a discrete representation of local orientation. A symmetry finder has been developed which uses the intensity-based method to search an image for compact regions which display some degree of mirror symmetry due to intensity similarities across a straight axis. In a different approach, we look at symmetry as a bilateral relationship between local orientations. A symmetryenhancing edge detector is presented which indicates edges dependent on the orientations at two different image positions. SEED, as we call it, is a detector element implemented by a feedforward network that holds the symmetry conditions. We use SEED to find the contours of symmetric objects of which we know the axis of symmetry from the intensity-based symmetry finder. The methods presented have been applied to the problem of visually guided car-following. Real-time experiments with a system for automatic headway control on motorways have been successful.
KeywordsLocal Orientation Visual Tracking Detector Element Directional Filter Symmetric Object
- 1.Friedberg, S. A.: Finding Axes of Skewed Symmetry. Computer Vision, Graphics, and Image Processing 34 (1986) 138–155Google Scholar
- 2.Marola, G.: Using Symmetry for Detecting and Locating Objects in a Picture. Computer Vision, Graphics, and Image Processing 46 (1989) 179–195Google Scholar
- 3.Saint-Marc, P., Medioni, G.: B-Spline Contour Representation and Symmetry Detection, Proceedings, First European Conf. on Computer Vision, Antibes, France (1990) 604–606Google Scholar