Instrumentation for Empirical Studies in the Modeling of Visual Appearance

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EIA 0224431Belhumeur, Peter N.Kriegman, David J.Columbia University Title: CISE RR: Instrumentation for Empirical Studies in the Modeling of Visual Appearance This project, supporting experimental validation of computer vision algorithms for shape modeling and analysis, aims at building two independent systems to support computer vision. Methods for shape reconstruction and reflectance recovery, termed Helmholtz reciprocity stereopsis and light field reconstruction that exploit previously neglected physical principles, are able to recover surface shape regardless of the object's BRDF. The two special purpose imaging systems will be built at Columbia University and the University of Illinois at Urbana-Champaign (UIUC). The Columbia rig, composed of sixteen imaging modules that can be arranged in different configurations, directly supports research in Helmholtz reciprocity stereopsis. The UIUC rig, consisting of two arms that move their endpoints over the surface of a sphere, directly supports the light field reconstruction method. The two new pieces of hardware will contribute to the following four projects:Helmholtz Stereopsis,Light Field Reconstruction,Image-Based Modeling and Rendering, andTexture and Reflectance Estimation from Small Datasets.The first project exploits the symmetries in an object's surface reflectance. The Helmholtz stereopsis method can reconstruct surfaces with complex reflectance, e.g., highly non-Lambertian. The Helmholtz rig will be used to gather datasets of objects in a manner such that they can be processed using the Helmholtz stereopsis shape recovery method. The second uses images gathered from a double covering of a surface's incident light field to reconstruct both the surface shape and an effective bi-directional reflectance distribution on a point-by-point basis. The illumination/viewpoint rig will be used to gather data in a manner such that it can be processed with the light field reconstruction method. The third utilizes the datasets gathered by both rigs for image-based and modeling projects to render photorealistic images of objects under novel viewpoint and arbitrary illuminations. Datasets of objects, with their 3-D shape reconstructed, are collected and their reflectance is modeled. These models of shape and reflectance are then used to synthesize novel images of the objects and composite them into still pictures and video footage. The objects will be catalogued by their visual appearance. The last project uses the datasets gathered by the light field rendering rig for developing low-dimensional models of texture and reflectance. These models are then used to estimate texture and reflectance properties from a small number of images. Thus, images characterizing reflectance properties of a wide variety of materials will be created and distributed satisfying the following goals to Develop, refine, analyze, and empirically validate the method of Helmholtz stereopsis,Develop, refine, and analyze the light field reconstruction method,Apply the reconstruction methods to image-based rendering, andDevelop and refine data-driven low-dimensional non-parametric models for surface reflection and textures that vary with viewpoint and lighting.