Color reflectance modeling using a polychromatic laser range sensor

Abstract

This paper describes a system for simultaneously measuring the 3-D shape and color properties of objects. Range data are obtained by triangulation over large volumes of the scene, whereas color components are separated by means of a white laser. Details are given concerning the modeling and the calibration of the system for bidirectional reflectance-distribution function measurements. A reflection model is used to interpret the data collected with the system in terms of the underlying physical properties of the target. These properties are the diffuse reflectance of the body material, the Fresnel reflectance of the air-media interface, and the slope surface roughness of the interface. Experimental results are presented for the extraction of these parameters. By allowing the subtraction of highlights from color images and the compensation for surface orientation, spectral reflectance modeling can help to understand 3-D scenes. A practical example is given where a color and range image is processed to yield uniform regions according to material pigmentation.

Recovery of Reflectances and Varying Illuminants from Multiple Views

“…The dual approach, reflectance modeling, consists in assuming that the point light source is known. It recovers sophisticated reflectance properties with specular and diffuse parameters [11,2,21,13]. This has been extended to multiple known point light sources, as well as indirect illumination effects [25].…”

Illumination Distribution from Shadows

“…Again, if we use a sufficiently large number of pixels for the estimation, we are able to solve for a solution set of unknown illumination radiance L(θ i , φ i )(i = 1, 2, ...., n). 1 We established the correspondence between the 3D world coordinate system in the scene and the 2D image coordinate system by using the camera calibration algorithm proposed by Tsai [21]. From the calibration process, a plane of z = 0 is also defined on the calibration board, onto which the occluding object cast shadows.…”

“…In the past, the first two kinds of analyses, the shape recovery and the reflectance recovery, have been intensively studied using the shape from shading method [7,8,9,16] as well as through reflectance analysis research [1,12,13,15,18] . In contrast, there has been little progress on the subject of recovering illumination from the knowledge of the shape and the reflectance of an object surface.…”

Acquiring, stitching and blending diffuse appearance attributes on 3D models

“…Mesh simplification tools [12,7] are generally adopted to reduce the shape redundancy of the output produced, and to support simple management of the models even on a portable computer. One critical question is how to acquire the surface attributes and how to link it to the shape description [1,14,19,10,28,31,29,25,27,35,20].…”

“…• the surface attributes acquisition should guarantee good accuracy and high resolution, especially in the case of objects with a complex shape and a highly textured surface with non-uniform reflectance properties (which cannot be acquired using most of the proposed approaches [1,28,19]);…”