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Unformatted text preview: Appearing in Proc. Workshop on Representations of Visual Scenes, Cambridge MA, 1995. Physically-Valid View Synthesis by Image Interpolation Steven M. Seitz Charles R. Dyer seitz@cs.wisc.edu dyer@cs.wisc.edu Department of Computer Sciences University of Wisconsin Madison, WI 53706 very successful in the entertainment industry, providing a simple mechanism capable of producing visually appealing transformations from one image to another. Despite the popularity of morphing techniques, little attention has focused on the physical validity of the resulting images. In this paper, we investigate the feasibility of using image warping techniques for view synthesis. We use the term view synthesis to refer to the rendering of images of an observed object or scene from new viewpoints. A special case of view synthesis is view interpolation, which concerns the synthesis of a continuous series of views starting at one known viewpoint and ending at another. In the context of these de nitions, the main result of this paper is that for a broad class of scenes and images image interpolation is a physically valid mechanism for view interpolation. This result provides a theoretical basis for morphing techniques and demonstrates that views can be synthesized with simple 2D image operations. In addition, we demonstrate constructively that, unlike 3D structure recovery, view interpolation is well-posed and does not su er from the aperture problem. The result depends on an assumption of monotonicity which requires that corresponding scene points appear in the same order in both images. Practical applications of view synthesis include virtual teleconferencing 1, 2 with limited network bandwidth. By using view synthesis at the receiving end, di erent views of the participants can be synthesized from a small number of transmitted views. View synthesis has also been used to create panoramic mosaic images 3 . Several images of a scene can be combined to create a single mosaic image by warping the images to be consistent with a common viewpoint. An advantage of image-based view synthesis is that rendering time is independent of scene complexity. This property can be exploited to speed up rendering of complex scenes 4 . The remainder of the paper is structured as follows: Section 2 reviews related work in image-based view synthesis. Section 3 describes the projection model and relevant terminology. Section 4 formalizes the notion of view interpolation and proves that the problem is well-posed under a general visibility assumption. The feasibility of using image interpolation for view in- Abstract Image warping is a popular tool for smoothly transforming one image to another. Morphing" techniques based on geometric image interpolation create compelling visual e ects, but the validity of such transformations has not been established. In particular, does 2D interpolation of two views of the same scene produce a sequence of physically valid in-between views of that scene? In this paper, we describe a simple image recti cation procedure which guarantees that interpolation does in fact produce valid views, under generic assumptions about visibility and the projection process. T...
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