640 A PROBABILISTIC APPROACH TO GEOMETRIC HASHING USING LINE FEATURES F. Tsai, June 1993 Most current object recognition algorithms assume reliable image segmentation, which in practice is often not available. We examine the combination of the Hough Transform with a variation of Geometric Hashing as a technique for model-based object recognition in seriously degraded single intensity images. Prior work on the performance analysis of geometric hashing has focused on point features and shown its noise sensitivity. This paper uses line features to compute recognition invariants in a potentially more robust way. We investigate the statistical behavior of these line features analytically. Various viewing transformations, which 2-D (or flat 3-D) objects undergo during image formation, are considered. For the case of affine transformations, which are often suitable substitutes for more general perspective transformations, we show experimentally that the technique is noise resistant and can be used in highly occluded environments.