Multi-Scale Video Cropping
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Hazem El-Alfy, David Jacobs
and Larry Davis, “Multi-Scale Video Cropping,” ACM Multimedia 07, Sep.
2007 Paper: pdf (446 KB) Presentation: ppt (3.95 MB) [20% acceptance: 18 out of 90 submissions to
the Applications Track.] Videos: (download with presentation in same folder. Do NOT modify names!) video1 (1.7MB), video2 (2.4MB), video3 (6.9MB), video4 (5.2MB), video5 (4.1MB), video6 (1.6MB), video7 (4.6MB), video8 (4.3MB), video9 (4.2MB). Additional videos (not on presentation): [AVI format – DivX codec compression] video10 (14.8MB) Matlab code: zip (19.4KB) |
Assigning Cameras to Subjects in Surveillance Systems
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Given an environment with obstacles, and many people moving through it, we construct a separate video for each person, by stitching together video segments from multiple cameras over time. We employ a novel approach, using bipartite matching, to assign a camera to each person as a function of time, with camera switches when needed. When the number of people is large, we cluster as many people as possible into small groups, then assign cameras to groups using a minimum cost matching algorithm. The method is tested using numerous runs from different simulators. Hazem El-Alfy, David Jacobs and Larry Davis,
“Assigning Cameras to Subjects in Video Surveillance Systems,” IEEE ICRA
’09, May 2009. Paper: pdf (338 KB). Presentation: zip (1.5 MB). |
Stochastic Multiple Scattering
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We solve the problem of wave scattering by multiple spheres, subject to uncertain boundary conditions. Uncertainty is modeled through a Karhunen-Loève expansion of the right hand side. Useful properties of spheres are exploited, by discretizing the problem in a basis of spherical harmonics, and speed-up is achieved through multipole reexpansion. Supervised
by: Howard Elman and Ramani Duraiswami. Hazem
El-Alfy, “Multiple Scattering from N Spheres with Uncertain Source
Location Using Stochastic Multipoles,” Scholarly Paper, M.Sc., Computer
Science, Paper: pdf Matlab
code: zip |
Implicitization Problem
f(x, y) = 2x4 - 3x2y
+ y4 - 2y3 + y2 = 0 |
Implicitization is the process of converting equations of curves and surfaces from parametric form into implicit form. We implement algorithms for currently available methods. In addition, we devise a new method for problems for which no direct method is available. The method relies on producing an approximation of the input problem. Several variants of this new method try to offer a compromise between its accuracy and versatility. Supervisors: Abdel-Karim Aboul-Hassan
and Mohamed Sayed. Hazem
El-Alfy, “Computer
Algebra and its Applications,” M. Sc.
Thesis, Engineering
Mathematics Department, Faculty of Engineering, Thesis: pdf |