Browsing by Author "Singels, Francois"
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- ItemReal-time stereo reconstruction using hierarchical dynamic programming and LULU filtering(Stellenbosch : University of Stellenbosch, 2010-03) Singels, Francois; Brink, Willie; Herbst, B. M.; University of Stellenbosch. Faculty of Science. Dept. of Mathematical Sciences.ENGLISH ABSTRACT: In this thesis we consider the essential topics relating to stereo-vision and the correspondence problem in general. The aim is to reconstruct a dense 3D scene from images captured by two spatially related cameras. Our main focus, however, is on speed and real-time implementation on a standard desktop PC. We wish to use the CPU to solve the correspondence problem and to reserve the GPU for model rendering. We discuss three fundamental types of algorithms and evaluate their suitability to this end. We eventually choose to implement a hierarchical version of the dynamic programming algorithm, because of the good balance between accuracy and speed. As we build our system from the ground up we gradually introduce necessary concepts and established geometric principles, common to most stereovision systems, and discuss them as they become relevant. It becomes clear that the greatest weakness of the hierarchical dynamic programming algorithm is scanline inconsistency. We nd that the one-dimensional LULU- lter is computationally inexpensive and e ective at removing outliers when applied across the scanlines. We take advantage of the hierarchical structure of our algorithm and sub-pixel re nement to produce results at video rates (roughly 20 frames per second). A 3D model is also constructed at video rates in an on-line system with only a small delay between obtaining the input images and rendering the model. Not only is the quality of our results highly competitive with those of other state of the art algorithms, but the achievable speed is also considerably faster.