Photometric Method For Determining Surface Orientation From Multiple Images

Woodham, Robert J.

doi:10.1117/12.7972479

Cited by 1,715 publications

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“…From these luminance distributions, it is theoretically possible to estimate the local surface structure uniquely (Woodham, 1980). Predictions Woodham (1980) showed theoretically that the local surface structure can be reconstructed uniquely from at least three different luminance distributions. The luminance distributions that belong to the same shape will be obtained by varying the illuminant direction.…”

Section: Experiments 3 Local Shape From An Animated Sequence Of Intensmentioning

confidence: 99%

“…Thus, in order to find the local surface structure on the basis of shading, one has to make assumptions about the illuminant direction and the surface properties (Horn, 1975(Horn, , 1977Pentland, 1984Pentland, , 1989. Another method to estimate the local surface structure from shading is to combine the information given by several intensity patterns of one shape (Woodham, 1980). Most computational theories on shape from shading calculate the surface shape locally (Horn, 1975(Horn, , 1977Pentland, 1984Pentland, , 1989Woodham, 1980).…”

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confidence: 99%

“…Another method to estimate the local surface structure from shading is to combine the information given by several intensity patterns of one shape (Woodham, 1980). Most computational theories on shape from shading calculate the surface shape locally (Horn, 1975(Horn, , 1977Pentland, 1984Pentland, , 1989Woodham, 1980). It is not clear whether human observers are able to judge the local shape of an object on the basis of shading.…”

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Perception of local shape from shading

Erens

Kappers

Koenderink

1993

Perception & Psychophysics

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Theoretically, metric solid shape is not determined uniquely by shading. Consequently, human vision has difficulty in categorizing shape when shading is the only cue. In the present research, subjects were required to categorize shaded quadric surfaces. We found that they were rather poor at this task; they confused hyperbolic and elliptic (both convex and concave) shapes easily. When a cast shadow visually indicated the direction of the illuminant, they were able to notice the concavity or convexity of elliptic shapes. However, they still confused elliptic and hyperbolic ones. Finally, when an animated sequence of eight intensity patterns belonging to one quadric shape had been displayed, the subjects were able to categorize the quadrics. However, the results are still quite moderate. Our experiments indicate that local shading structure is only a weak shape cue when presented in the absence of other visual cues. 145With the present generation of rendering algorithms, it is apparently relatively easy to generate very "natural" images on a computer screen. The three-dimensional impression created by these images is very compelling. However, such an informal observation has to be quantified. Very little research has been done on the perception of solid shape on the basis of shading.Computer images provide several visual cues that potentially contribute to the perception of solid shape (Gibson, 1950). The role of shading in these images is complicated because extracting shape from shading is not a trivial task. The shading is determined by the surface orientation, the illuminant direction, and the surface properties. This means that the same luminance distribution can be generated by several different surfaces. For instance, the luminance distribution of concave and convex spheres is exactly the same. Thus, in order to find the local surface structure on the basis of shading, one has to make assumptions about the illuminant direction and the surface properties (Horn, 1975(Horn, , 1977Pentland, 1984Pentland, , 1989. Another method to estimate the local surface structure from shading is to combine the information given by several intensity patterns of one shape (Woodham, 1980). Most computational theories on shape from shading calculate the surface shape locally (Horn, 1975(Horn, , 1977Pentland, 1984Pentland, , 1989Woodham, 1980). It is not clear whether human observers are able to judge the local shape of an object on the basis of shading.Several psychophysical experiments report observers' ability to estimate local surface structure from shading (Biilthoff & Mallot, 1988;Mingolla & Todd, 1986;Todd & Mingolla, 1983;Todd & Reichel, 1991). These experiments indicated that human observers are very poor at this. Other experiments have shown that observers cannot distinguish local shapes such as concave and convex spheres when they do not know the illuminant direction (Berbaum, Bever, & Sup Chung, 1984;Ramachandran, 1988). In most of these studies, a very restricted set of shapes such as spheres (Berbaum et al., 1984), ...

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Section: Experiments 3 Local Shape From An Animated Sequence Of Intensmentioning

confidence: 99%

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Perception of local shape from shading

Erens

Kappers

Koenderink

1993

Perception & Psychophysics

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“…Surfaces can be recovered by using a technique known as photometric stereo Forsyth & Ponce (2002); Horn et al (1978);Silver (1980);Woodham (1989 accomplished by using minimum squares for solving a linear system of M equations, each one expressing the pixel intensity as a function of the direction of the incident light (Lambert's cosine law) for each pixel. From surface normals maps, it is possible to reconstruct the surface of each face by using shapelets Kovesi (2005).…”

Section: Recovery Of the Face Surface For Each Training Identitymentioning

confidence: 99%

Face Image Synthesis and Interpretation Using 3D Illumination-Based AAM Models

Ayala-Raggi¹,

Altamirano²,

Cruz-Enriquez³

2011

New Approaches to Characterization and Recognition of Faces

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“…Photometric stereo, by using multiple images, each taken with the same viewpoint but a different illuminant explicitly known [23,24,9] or implicitly determined [1], recovers a non-uniform albedo, as well as the surface orientation.…”

Section: Previous Workmentioning

confidence: 99%

Recovery of Reflectances and Varying Illuminants from Multiple Views

Luong

Fua

Leclerc

2002

Computer Vision — ECCV 2002

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Abstract. We introduce a new methodology for radiometric reconstruction from multiple images. It opens new possibilities because it allows simultaneous recovery of varying unknown illuminants (one per image), surface albedoes, and cameras' radiometric responses. Designed to complement geometric reconstruction techniques, it only requires as input the geometry of the scene and of the cameras. Unlike photometric stereo approaches, it is not restricted to images taken from a single viewpoint. Linear and non-linear implementations in the Lambertian case are proposed; simulation results are discussed and compared to related work to demonstrate the gain in stability; and results on real images are shown.

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Photometric Method For Determining Surface Orientation From Multiple Images

Cited by 1,715 publications

References 0 publications

Perception of local shape from shading

Perception of local shape from shading

Face Image Synthesis and Interpretation Using 3D Illumination-Based AAM Models

Recovery of Reflectances and Varying Illuminants from Multiple Views

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