Statistics-based colour constancy algorithms work well as long as there are many colours in a scene, they fail however when the encountering scenes comprise few surfaces. In contrast, physics-based algorithms, based on an understanding of physical processes such as highlights and interre ections, are theoretically able to solve for colour constancy even when there are as few as two surfaces in ...

Since modeling reflections in image processing is a difficult task, most computer vision algorithms assume that objects are Lambertian and that no lighting change occurs. Some photometric models can partly answer this issue by assuming that the lighting changes are the same at each point of a small window of interest. Through a study based on specular reflection models, we explicit the assumpti...

Since the precise modeling of reflection is a difficult task, most feature points trackers assume that objects are lambertian and that no lighting change occurs. To some extent, a few approaches answer these issues by computing an affine photometric model or by achieving a photometric normalization. Through a study based on specular reflection models, we explain explicitly the assumptions on wh...

This thesis describes the automatic reconstruction of 3D object models from observation of real objects. As a result of the significant advancement of graphics hardware and image rendering algorithms, 3D computer graphics capability has become available even on low-end computers. However, it is often the case that 3D object models are created manually by users. That input process is normally ti...

We estimate surface normal maps of an object from either its diffuse or specular reflectance using four spherical gradient illumination patterns. In contrast to traditional photometric stereo, the spherical patterns allow normals to be estimated simultaneously from any number of viewpoints. We present two polarized lighting techniques that allow the diffuse and specular normal maps of an object...

The bidirectional reflectance characteristics of vegetation canopies vary with time of day and through the growing season. In this study the effects of sun and view angles on bidirectional reflectance factors from corn (Zea mays L.) canopies ranging in development from the six leaf stage to harvest maturity were examined. For nadir-acquired reflectance factors there was a strong solar angle dep...

One of the problems that hinders conventional methods for shape-from-shading is the presence of local specularities which may be misidenti.ed as high curvature surface features. In this paper we address the problem of estimating the proportions of Lambertian and specular re1ection components in order to improve the quality of surface normal information recoverable using shape-from-shading. The ...

This paper introduces a new image-based approach to capturing and modeling highly specular, transparent, or translucent objects. We have built a system for automatically acquiring high quality graphical models of objects that are extremely difficult to scan with traditional 3D scanners. The system consists of turntables, a set of cameras and lights, and monitors to project colored backdrops. We...