Browsing by Subject "Image sequences"

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    3-D motion estimation and wireframe adaptation including photometric effects for model-based coding of facial image sequences
    (IEEE, 1994-06) Bozdağı, G.; Tekalp, A. M.; Onural, L.
    We propose a novel formulation where 3-D global and local motion estimation and the adaptation of a generic wireframe model to a particular speaker are considered simultaneously within an optical flow based framework including the photometric effects of the motion. We use a flexible wireframe model whose local structure is characterized by the normal vectors of the patches which are related to the coordinates of the nodes. Geometrical constraints that describe the propagation of the movement of the nodes are introduced, which are then efficiently utilized to reduce the number of independent structure parameters. A stochastic relaxation algorithm has been used to determine optimum global motion estimates and the parameters describing the structure of the wireframe model. Results with both simulated and real facial image sequences are provided.
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    ItemOpen Access
    An improvement to MBASIC algorithm for 3-D motion and depth estimation
    (IEEE, 1994) Bozdağı, G.; Tekalp, A. M.; Onural, L.
    In model-based coding of facial images, the accuracy of motion and depth parameter estimates strongly affects the coding efficiency. MBASIC is a simple and effective iterative algorithm (recently proposed by Aizawa et al.) for 3-D motion and depth estimation when the initial depth estimates are relatively accurate. In this correspondence, we analyze its performance in the presence of errors in the initial depth estimates and propose a modification to MBASIC algorithm that significantly improves its robustness to random errors with only a small increase in the computational load.
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    ItemOpen Access
    Vision-based continuous Graffiti™-like text entry system
    (SPIE, 2004) Erdem, İ. A.; Erdem, M. E.; Atalay, V.; Çetin, A. Enis
    It is now possible to design real-time, low-cost computer version systems even in personal computers due to the recent advances in electronics and the computer industry. Due to this reason, it is feasible to develop computer-vision-based human-computer interaction systems. A vision-based continuous Graffiti™-like text entry system is presented. The user sketches characters in a Griffiti™-like alphabet in a continuous manner on a flat surface using a laser pointer. The beam of the laser pointer is tracked on the image sequences captured by a camera, and the corresponding written word is recognized from the extracted trace of the laser beam. © 2004 Society of Photo-Optical Instrumentation Engineers.