When: Wednesday, May 07, 10:00 a.m.- 11:30 a.m.

Where: 3305 Newell-Simon Hall

Yaser Sheikh, Carnegie Mellon University

SCS Faculty Candidate Talk

Abstract:
With the proliferation of camera-enabled cell phones, domestic robots, and wearable computers, moving cameras are being introduced /en masse/ into society. The confluence of camera motion and the motion of objects in the scene complicates the task of understanding the scene from video. In this talk, I discuss how and when it is possible to disambiguate these two sources of motion, towards the goal of analyzing dynamic scenes from moving cameras.

I begin by considering a single camera viewing a dynamic scene. Unlike contemporary approaches to this problem, which try to model the variation in the shape of objects, I show that modeling the variation of points along time is better motivated physically and produces more stable reconstructions. This model also intuitively characterizes the inherent reconstruction ambiguity for a single camera and motivates the study of dynamic scenes from /multiple/ moving cameras. I present the case for conducting this analysis in spacetime, where a dynamic scene is considered a body in spacetime, and each video a spacetime image of this body. Through this representation, I demonstrate that classic algorithms in multiview geometry that deal with static scenes can be lifted to spacetime, and applied directly for dynamic scene analysis. The analogues of factorization approaches and the fundamental matrix are described, leading to new, intuitive, relationships between the epipolar geometries of perspective images, linear pushbroom images and epipolar plane images.

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