Unifying diffuse and specular reflections for the photometric stereo problem

Mecca, Roberto; Quéau, Yvain

doi:10.1109/wacv.2016.7477643

Cited by 19 publications

(17 citation statements)

References 36 publications

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“…The same problem exists for the method in Ref. [38], which needs the mean depth value. However, this information is unknown and is not always available in real world applications.…”

Section: Prior Knowledge Of Depth Unnecessarymentioning

confidence: 97%

“…As a result, a variational approach in Ref. [38] is considered to solve their model, using ten input images from purely specular or purely diffuse surfaces. Considering only the diffuse component or specular component alone is not sufficient for practical applications.…”

Section: Spatially Varying Materialsmentioning

confidence: 99%

“…[38], we do not use any smoothness constraints for object structure to tackle artifacts which can disrupt the recovery of fine details. Thus, surfaces with delicate geometric structures can be reconstructed by our approach: see Figs.…”

Section: Smoothness Constraints Unnecessarymentioning

confidence: 99%

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Photometric stereo for strong specular highlights

2018

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Photometric stereo is a fundamental technique in computer vision known to produce 3D shape with high accuracy. It uses several input images of a static scene taken from one and the same camera position but under varying illumination. The vast majority of studies in this 3D reconstruction method assume orthographic projection for the camera model. In addition, they mainly use the Lambertian reflectance model as the way that light scatters at surfaces. Thus, providing reliable photometric stereo results from real world objects still remains a challenging task. We address 3D reconstruction by use of a more realistic set of assumptions, combining for the first time the complete Blinn-Phong reflectance model and perspective projection. Furthermore, we compare two different methods of incorporating the perspective projection into our model. Experiments are performed on both synthetic and real world images; the latter do not benefit from laboratory conditions. The results show the high potential of our method even for complex real world applications such as medical endoscopy images which may include many specular highlights.

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“…The same problem exists for the method in Ref. [38], which needs the mean depth value. However, this information is unknown and is not always available in real world applications.…”

Section: Prior Knowledge Of Depth Unnecessarymentioning

confidence: 97%

Section: Spatially Varying Materialsmentioning

confidence: 99%

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Photometric stereo for strong specular highlights

2018

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“…We extend the model presented in [2] which includes perspective viewing geometry, point light source parameterization and Blinn-Phong specular reflectance [1], by considering non-negligible ambient light as an additional pixel-wise component (A(x, y)) to the usual irradiance model. Theory We assume the following irradiance equation for the i th light source placed at point (ξ i , η i , ζ i ):…”

Section: Extended Abstractmentioning

confidence: 99%

Near-Field Photometric Stereo in Ambient Light

Logothetis¹,

Mecca²,

Quéau³

et al. 2016

Procedings of the British Machine Vision Conference 2016

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Extended AbstractShape recovery from shading information has recently regained importance due to the improvement towards making the Photometric Stereo technique more reliable in terms of appearance of reflective objects. However, although more advanced models have been lately proposed, 3D scanners based on this technology do not provide reliable reconstructions as long as the considered irradiance equation neglects any additive bias. Depending on the context, such bias assumes different physical meanings. For example, in murky water it is known as saturated backscattered effect or for acquisition in pure air medium it is known as ambient light. Although the theoretical part covers both cases, this work mostly focuses on the pure air acquisition case. Indeed, we present a new approach based on ratios of differences of images where an exhaustive set of physical features are tackled while dealing with Photometric Stereo acquisition with considerable importance for the ambient light. To the best of our knowledge, this is the first attempt to recover the shape from Photometric Stereo considering simultaneously perspective viewing geometry, nonlinear light propagation, both specular and diffuse reflectance plus the additive bias of the ambient light.Contribution We propose a new approach for the PS which allows 3D reconstructions that have data with a complete list of physical features that are not negligible when images are taken in outdoor scenes. We extend the model presented in [2] which includes perspective viewing geometry, point light source parameterization and Blinn-Phong specular reflectance [1], by considering non-negligible ambient light as an additional pixel-wise component (A(x, y)) to the usual irradiance model. TheoryWe assume the following irradiance equation for the i th light source placed at point (ξ i , η i , ζ i ):

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“…With the aim to extend and derive a well-posed mathematical formulation for the model presented in [37], in this work we propose a method capable of performing the PS technique in much less controlled setups by simultaneously handling several nonlinear physical effects in order to make it as close as possible to real-world scenarios. With the aim to extend and derive a well-posed mathematical formulation for the model presented in [37], in this work we propose a method capable of performing the PS technique in much less controlled setups by simultaneously handling several nonlinear physical effects in order to make it as close as possible to real-world scenarios.…”

mentioning

confidence: 99%

A Single-Lobe Photometric Stereo Approach for Heterogeneous Material

Mecca¹,

Quéau²,

Logothetis³

et al. 2016

SIAM J. Imaging Sci.

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Shape from shading with multiple light sources is an active research area, and a diverse range of approaches have been proposed in recent decades. However, devising a robust reconstruction technique still remains a challenging goal, as the image acquisition process is highly nonlinear. Recent Photometric Stereo variants rely on simplifying assumptions in order to make the problem solvable: light propagation is still commonly assumed to be uniform, and the Bidirectional Reflectance Distribution Function is assumed to be diffuse, with limited interest for specular materials. In this work, we introduce a well-posed formulation based on partial differential equations (PDEs) for a unified reflectance function that can model both diffuse and specular reflections. We base our derivation on ratio of images, which makes the model independent from photometric invariants and yields a well-posed differential problem based on a system of quasi-linear PDEs with discontinuous coefficients. In addition, we directly solve a differential problem for the unknown depth, thus avoiding the intermediate step of approximating the normal field. A variational approach is presented ensuring robustness to noise and outliers (such as black shadows), and this is confirmed with a wide range of experiments on both synthetic and real data, where we compare favorably to the state of the art.Reflectance. Most of the research done till now for the PS technique has assumed purely diffuse reflectance as the Bidirectional Reflectance Distribution Function (BRDF). Unlike (a) and (b), shape recovery from specular shading still remains a challenging goal since most of the common materials provide specular highlights that prevent reasonable reconstructions by the PS technique.Regarding shading models for specular highlights, several dedicated irradiance equations have been presented so far. First, Torrance and Sparrow [56] presented a physical model based on radiometry principles. Later, Phong [48] showed an empirical model which basically extended the cosine law, making it depend also on the viewer direction. The Blinn-Phong shading model [4] extended further the previous one by eliminating some limitation in the analytical formulation. Then Cook and Torrance [14] provided a well-known specular model based on a strongly nonlinear physical theory. Other important models for specular BRDFs can be found in [33], and interesting comparisons among some of them have been performed in [44].Instead of simplifying the PS problem by removing specularity, other works dealt with the images as they are, having both specular and diffuse components. Nayar, Ikeuchi, and Kanade [43] assumed hybrid surfaces by summing diffuse and specular components using the Beckmann and Spizzichino [3] reflection model, allowing them to locally reconstruct the shape of the object. Ikeuchi [28] faced the PS problem with specular reflectance by introducing a smoothness prior on the surface, which was shown to be realistic for several industrial applications, though this approach is limite...

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Unifying diffuse and specular reflections for the photometric stereo problem

Cited by 19 publications

References 36 publications

Photometric stereo for strong specular highlights

Photometric stereo for strong specular highlights

Near-Field Photometric Stereo in Ambient Light

A Single-Lobe Photometric Stereo Approach for Heterogeneous Material

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