Numerical shape-from-shading revisited

Santo, Hiroaki; Samejima, Masaki; Matsushita, Yasuyuki

doi:10.1186/s41074-018-0044-9

Cited by 5 publications

(7 citation statements)

References 40 publications

(66 reference statements)

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“…A third factor must be considered. Whatever the exact method used, all shape‐from‐shading approaches use grey levels to compute the 3D depth map 32 . Therefore, they can only show very high sensitivity to minute changes in lighting of the raw skin texture images.…”

Section: Discussionmentioning

confidence: 99%

“…Taking advantage of its embedded validation application, its real-time connection to data storage servers/analysis software, and the possibility to produce images with unidirectional light from different angles, its analysis software suite was further developed to produce 3D depth maps based on a shape-from-shading approach. [30][31][32] This feature enables the extraction of a single skin profile, allowing the computing of skin furrows and plateaus parameters from the skin microrelief under real-life conditions. Yet, the Spa parameter extracted from raw skin texture images, Ra and Rq, as well as microrelief parameters extracted from 3D depth maps show higher variability.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of a new connected portable camera for the analysis of skin microrelief and the assessment of the effect of skin moisturisers

Gougeon¹,

Hernandez²,

Chevrot³

et al. 2022

Skin Research and Technology

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Background Silicone replicas and non‐contact methods are effective methods to analyse the micrometric scale of the skin microrelief. Yet, they imply data capture in research facilities. The capabilities of a new connected portable camera were evaluated to analyse microrelief under nomadic conditions, also studying the effect of moisturisers. Materials and methods 3D depth maps were constructed using shape‐from‐shading algorithms. Roughness heterogeneity (Spa) was computed, and skin profiles were extracted to calculate roughness amplitude (Ra, Rq), as well as furrows/plateaus characteristics. Validation of the connected camera was performed on tanned cowhide leather and on the inner forearm skin of a single subject. The forearms of 18 subjects (23–60 years old) were also evaluated. While living their regular life, they self‐performed triplicate acquisitions at various times. The effects of a placebo and of cream containing moisturisers—saccharide isomerate, urea or xylitylglucoside–anhydroxylitol–xylitol—were investigated, using untreated control skin as a reference. Results Validation of the device on leather and forearm skin shows high repeatability. The 18 subjects show the known correlation between age and changes in microrelief. While testing formulas, 8 h after a single application, all decreased Spa (−1.6/−2.1 folds). Only saccharide isomerate and xylitylglucoside–anhydroxylitol–xylitol decreased Ra (−2.4/−2.8 folds). The sectional area of plateaus was reduced from −1.5 (urea) to −2.1 folds (xylitylglucoside–anhydroxylitol–xylitol). The height of plateaus is also decreased by all moisturisers, from −1.5 (urea) to −2.1 folds (xylitylglucoside–anhydroxylitol–xylitol). Conclusion This novel camera device enables microrelief analysis under nomadic conditions, allowing monitoring its changes along the day and upon moisturisers’ application.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Evaluation of a new connected portable camera for the analysis of skin microrelief and the assessment of the effect of skin moisturisers

Gougeon¹,

Hernandez²,

Chevrot³

et al. 2022

Skin Research and Technology

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“…Beginning with the work of B. Horn [1,2,3], Shape from Shading (SfS), algorithms enjoy a long history in computing science research [4,5,6,7,8], continue to attract theoretical investigation in the field of computer vision [9,10,11,12,13,14,15,16,17,18,19,20] and find many practical applications, e.g. in planetary research (Photoclinometry), industrial automation, medical imaging or face recognition [21,22,23,24,25,26,27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Fast Quadratic Shape From Shading With Unknown Light Direction

Yalpani¹

2021

Preprint

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An algorithm is proposed that extracts 3D shape from shading information in a digital image. The algorithm assumes that there is only a single source of light producing the image, that the surface of the shape giving rise to the image is Lambertian (matte) and that its shape can be locally approximated by a quadratic function. Previous work shows that under these assumptions, robust shape from shading is possible, though slow for large images because a non-linear optimization method is applied in order to estimate local quadratic surface patches from image intensities. The work presented here shows that local quadratic surface patch estimates can be computed, without prior knowledge of the light source direction, via a linear least squares optimization, thus greatly improving the algebraic complexity and run-time of this existing algorithms.

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“…e 3D shape was reconstructed by minimising a quadratic cost functional. More recently, Santo et al [20] revisited the numerical SFS approach of Ikeuchi and Horn [18] and described corresponding solution that was built upon different convex relaxation strategies. It is worth mentioning that Quéau et al [21] combined the advantages of optimisation methods and PDE-based methods and built a generic variational solution that is suitable for SFS under natural illumination and can handle a variety of scenarios for various lighting and camera projection.…”

Section: Introductionmentioning

confidence: 99%

A Unified Shape-From-Shading Approach for 3D Surface Reconstruction Using Fast Eikonal Solvers

Wang

Zhang

Cheng

2020

International Journal of Optics

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Object shape reconstruction from images has been an active topic in computer vision. Shape-from-shading (SFS) is an important approach for inferring 3D surface from a single shading image. In this paper, we present a unified SFS approach for surfaces of various reflectance properties using fast eikonal solvers. The whole approach consists of three main components: a unified SFS model, a unified eikonal-type partial differential image irradiance (PDII) equation, and fast eikonal solvers for the PDII equation. The first component is designed to address different reflectance properties including diffuse, specular, and hybrid reflections in the imaging process of the camera. The second component is meant to derive the PDII equation under an orthographic camera projection and a single distant point light source whose direction is the same as the camera. Finally, the last component is targeted at solving the resultant PDII equation by using fast eikonal solvers. It comprises two Godunov-based schemes with fast sweeping method that can handle the eikonal-type PDII equation. Experiments on several synthetic and real images demonstrate that each type of the surfaces can be effectively reconstructed with more accurate results and less CPU running time.

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Numerical shape-from-shading revisited

Cited by 5 publications

References 40 publications

Evaluation of a new connected portable camera for the analysis of skin microrelief and the assessment of the effect of skin moisturisers

Evaluation of a new connected portable camera for the analysis of skin microrelief and the assessment of the effect of skin moisturisers

Fast Quadratic Shape From Shading With Unknown Light Direction

A Unified Shape-From-Shading Approach for 3D Surface Reconstruction Using Fast Eikonal Solvers

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