Lambertian photometric stereo with uncalibrated light directions and intensities determines the surface normals only up to an invertible linear transformation. We show that if object reflectance is a sum of Lambertian and specular terms, the ambiguity reduces into a 2dof group of transformations (compositions of isotropic scaling, rotation around the viewing vector, and change in coordinate fra...

Optical reflectance probes are often used as tools to obtain optical spectra from superficial tissues and subsequently determine optical and physiological properties associated with early stage cancer. These probes, when placed directly on the tissue, are known to cause significant pressure-dependent changes in local optical properties. To address this, we fit the probe with an optical device t...

model [2] has been generally considered in both computer graphics and computer vision areas as a good Since the surface reflectance is a function of the geophysics-based model to describe the specular reflecmetrical components and the physical surface chartion of rough surfaces. However, since this model is acteristics, the reflectance parameters can be esticomplicated in nature, the simplified...

The calcium-mediated interaction of DNA with monolayers of the non-toxic, zwitterionic phospholipid, 1,2-distearoyl-sn-glycero-3-phosphocholine when mixed with 50 mol% of a second lipid, either the zwitteronic 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine or neutral cholesterol was investigated using a combination of surface pressure-area isotherms, Brewster angle microscopy, external reflectan...

We consider the problem of simultaneously estimating surface texture map and the pseudo illumination, which is the combined effect of illumination and surface BRDF, given the object geometry and its calibrated images taken from multiple viewpoints. We derive the bilinear reflection equation that relates the texture albedos and the pseudo illumination to the surface reflectance. The reflection e...

Two important aspects of part inspection are the measurement of surface shape and surface roughness. We propose a noncontact method of measuring surface shape and surface roughness. The method, which we call “four light photometric stereo”, uses four lights which sequentially iUuminate the object under inspection, and a video camera for taking images of the object. Conceptually, the problem we ...

Abstract: This paper describes a method for 3-D surface estimation based on reflection measurements in different orientations of the light source and the paper. To facilitate the estimation, surface facets that probably support specular reflection were marked and isolated, so as to enable the application of simple Lambertian reflectance model over those non-specular reflection points. A compute...

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: ligh...

Satellite remotely sensed images with a resolution of 1 m are expected to be available in the near future. These images are well suited for the study of inhomogenous areas like cities. This paper presents research projects of our group concerning the bidirectional reeectance properties of man-made surfaces, such as roofs, streets, etc. The BRDF eeects (like e.g. specular reeection for forward s...

Wavelength dependent Monte Carlo rendering can correctly and generally capture effects such as spectral caustics (rainbows) and chromatic abberation. It also improves the colour accuracy of reflectance models and of illumination effects such as colour bleeding and metamerism. The stratified wavelength clustering (SWC) strategy carries several wavelength stratified radiance samples along each li...