Reconstruction of Sculpture From Its Profiles With Unknown Camera Positions

Wong, Kwan-Yee K.; Cipolla, Roberto

doi:10.1109/tip.2003.821113

Cited by 51 publications

(41 citation statements)

References 43 publications

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“…Wong and Cipolla [13] describe a system that is calibrated from silhouette views using the constraint of circular motion. Once an initial visual hull model is constructed from an approximately circular motion sequence, additional views from arbitrary viewpoints can be added to refine the model.…”

Section: Introductionmentioning

confidence: 99%

Shape-from-Silhouette with Two Mirrors and an Uncalibrated Camera

Forbes

Nicolls

Jager

et al. 2006

Computer Vision – ECCV 2006

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Abstract. Two planar mirrors are positioned to show five views of an object, and snapshots are captured from different viewpoints. We present closed form solutions for calculating the focal length, principal point, mirror and camera poses directly from the silhouette outlines of the object and its reflections. In the noisy case, these equations are used to form initial parameter estimates that are refined using iterative minimisation. The self-calibration allows the visual cones from each silhouette to be specified in a common reference frame so that the visual hull can be constructed. The proposed setup provides a simple method for creating 3D multimedia content that does not rely on specialised equipment. Experimental results demonstrate the reconstruction of a toy horse and a locust from real images. Synthetic images are used to quantify the sensitivity of the self-calibration to quantisation noise. In terms of the silhouette calibration ratio, degradation in silhouette quality has a greater effect on silhouette set consistency than computed calibration parameters.

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Section: Introductionmentioning

confidence: 99%

Shape-from-Silhouette with Two Mirrors and an Uncalibrated Camera

Forbes

Nicolls

Jager

et al. 2006

Computer Vision – ECCV 2006

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“…These methods also assume that the shape of the object is reasonably complex; Silhouettes of simple objects such as spheres do not have enough features, and intricate objects like branches have too many, making it hard to find correspondences automatically. Wong and Cipolla propose a technique that can recover the epipolar geometry regardless of the complexity of the silhouette, using the outer epipolar tangency which is similar in spirit to our approach (Wong and Cipolla 2004). The camera motion, however, is limited to circular motion since they use the multi-view camera-based imaging system.…”

Section: Robust Reconstruction Of Visual Hullmentioning

confidence: 99%

“…While the idea of minimizing silhouette discrepancy is well known in the traditional multi-view camera-based SFS (Sinha et al 2004;Yezzi and Soatto 2003;Wong and Cipolla 2004;Hernán-dez et al 2007), the key advantage over prior work is the reduced number of parameters our algorithm needs to optimize (three per view for the light source position, instead of six per view for rotation and translation of the camera). In turn, this allows us to apply our technique to a much larger number of views than possible before.…”

Section: Optimizing Light Source Positionsmentioning

confidence: 99%

The Theory and Practice of Coplanar Shadowgram Imaging for Acquiring Visual Hulls of Intricate Objects

et al. 2008

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Acquiring 3D models of intricate objects (like tree branches, bicycles and insects) is a challenging task due to severe self-occlusions, repeated thin structures, and surface discontinuities. In theory, a shape-from-silhouettes (SFS) approach can overcome these difficulties and reconstruct visual hulls that are close to the actual shapes, regardless of the complexity of the object. In practice, however, SFS is highly sensitive to errors in silhouette contours and the calibration of the imaging system, and has therefore not been used for obtaining accurate shapes with a large number of views. In this work, we present a practical approach to SFS using a novel technique called coplanar shadowgram imaging that allows us to use dozens to even hundreds of This is an extension and consolidation of our previous work on coplanar shadowgram imaging system (Yamazaki et al. 2007 views for visual hull reconstruction. A point light source is moved around an object and the shadows (silhouettes) cast onto a single background plane are imaged. We characterize this imaging system in terms of image projection, reconstruction ambiguity, epipolar geometry, and shape and source recovery. The coplanarity of the shadowgrams yields unique geometric properties that are not possible in traditional multi-view camera-based imaging systems. These properties allow us to derive a robust and automatic algorithm to recover the visual hull of an object and the 3D positions of the light source simultaneously, regardless of the complexity of the object. We demonstrate the acquisition of several intricate shapes with severe occlusions and thin structures, using 50 to 120 views.

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“…Using the notion of epipolar tangency points [11], there are some camera calibration methods just exploiting silhouettes [12,13,14].Although these methods also can provide accurate results, epipolar tangency points are few and sometimes not available per pair of images. Also, silhouettes are used to estimate pose of free-form objects [15].…”

Section: Related Workmentioning

confidence: 99%