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ETH Zurich - Department of Information Technology and Electrical Engineering - Computer Vision Laboratory


Fast PRISM: Branch and Bound Hough Transform for Object Class Detection

Alain Lehmann, Bastian Leibe, Luc Van Gool
International Journal of Computer Vision
Vol. 94, No. 2, pp. 175-197, June 2011


This paper addresses the task of efficient object class detection by means of the Hough transform. This approach has been made popular by the Implicit Shape Model (ISM) and has been adopted many times. Although ISM exhibits robust detection performance, its probabilistic formulation is unsatisfactory. The PRincipled Implicit Shape Model (PRISM) overcomes these problems by interpreting Hough voting as a dual implementation of linear sliding-window detection. It thereby gives a sound justification to the voting procedure and imposes minimal constraints. We demonstrate PRISM's flexibility by two complementary implementations: a generatively trained Gaussian Mixture Model as well as a discriminatively trained histogram approach. Both systems achieve state-of-the-art performance. Detections are found by gradient-based or branch and bound search, respectively. The latter greatly benefits from PRISM's feature-centric view. It thereby avoids the unfavourable memory trade-off and any on-line pre-processing of the original Efficient Subwindow Search (ESS). Moreover, our approach takes account of the features' scale value while ESS does not. Finally, we show how to avoid soft-matching and spatial pyramid descriptors during detection without losing their positive effect. This makes algorithms simpler and faster. Both are possible if the object model is properly regularised and we discuss a modification of SVMs which allows for doing so.

Link to publisher's page
  author = {Alain Lehmann and Bastian Leibe and Luc Van Gool},
  title = {Fast PRISM: Branch and Bound Hough Transform for Object Class Detection },
  journal = {International Journal of Computer Vision},
  year = {2011},
  month = {June},
  pages = {175-197},
  volume = {94},
  number = {2},
  keywords = {Object detection - Hough transform - Sliding-window - Branch and bound - Soft-matching - Spatial pyramid histograms}