Photometric stereo for general isotropic reflectances by spherical linear interpolation

Abstract

Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. We present a practical photometric stereo method that works with general isotropic reflectances. Unlike previous approaches that use special hardware setups or dense measurements, our method only requires dozens of random yet known lighting directions. By spherically interpolating the light source directions to approximate the scene appearance under desired lighting directions, our method separately computes azimuth and elevation angles of the surface normal for each pixel. The effectiveness and accuracy of the proposed method are validated using a measured reflectance database with 100 isotropic materials and various real-world objects. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-2 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-4 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-6 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-7 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-8 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-9 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 083104-10 August 2015 • Vol. 54(8) Li and Shi: Photometric stereo for general isotropic reflectances by spherical linear interpolation Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/23/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Boxin Shi received his BE degree from ...

Incorporating Lambertian Priors into Surface Normals Measurement

“…Some basic derivations for isotropy BRDFs were proposed in [30], [31]. Based on empirical models, some researchers applied isotropic constraints for the measurement of surface orientation [32], [33]. Shi et al [34] and Ikehata et al [7] further approximated the isotropic BRDFs by bivariate functions to deal with the instability of the estimation.…”

SPLINE-Net: Sparse Photometric Stereo Through Lighting Interpolation and Normal Estimation Networks

“…Some basic derivations for isotropy BRDFs are provided in [4,29,6]. Excellent performance has been achieved by methods based on empirical models, including combining isotropy and monotonicity with visibility constraint [14], using isotropic constraint for the estimation of elevation angle [3,27,20], and approximating isotropic BRDFs by bivariate functions [23,17,28]. However, most of these methods based on analytic models and empirical models are pixel-wise so that they cannot explicitly consider global illumination effects such as interreflection and cast shadows.…”

Deviation correction method for close-range photometric stereo with nonuniform illumination

“…The point light sources are placed far away from the object to approximate ideal illumination conditions. 10,11 But this solution cannot be used in practical applications that provide limited device space, such as those used for underwater robots 9,12 and monocular laparoscopy. 13 In this situation, the reconstruction errors caused by the nonuniform lighting cannot be ignored.…”