In this paper, we propose a new method for estimating jointly light sources and reflectance properties of an object seen through images. A classification process firstly identifies regions of the object having the same appearance. An identification method is then applied for jointly (i) deciding what light sources are actually significant and (ii) estimating diffuse and specular coefficients fo...

This paper aims to link the spectral and directional variations of the leaf Bidirectional Reflectance Distribution Function (BRDF) by differentiating specular and diffuse components. To do this, BRDF of laurel (Prunus laurocesarus), European beech (Fagus silvatica) and hazel (Corylus avellana) leaves were measured at 400 wavelengths evenly spaced over the visible (VIS) and near-infrared (NIR) d...

An integral part of computer graphics, machine vision and human vision understanding is modeling how a surface reflects light. There is a substantial body of work on models describing surface reflectance ranging from purely matte to purely specular. One of the advantages of diffuse reflectance is that the color and the intensity of the reflected light are separable for most materials. Color is ...

Reconstructing the 3D point mesh of an object from 2D images is a difficult problem. The task is even more complicated when the object has arbitrary and unknown surface reflectance. Traditional reconstructing techniques make explicit or implicit assumptions about the bidirectional reflectance distribution function (BRDF), which represents the surface reflectance. A widely used assumption is tha...

Using hyperspectral measurements made in the field, we show that the effective sea-surface reflectance ρ (defined as the ratio of the surface-reflected radiance at the specular direction corresponding to the downwelling sky radiance from one direction) varies not only for different measurement scans, but also can differ by a factor of 8 between 400 nm and 800 nm for the same scan. This means th...

Reflectance parameters condition the appearance of objects in photorealistic rendering. Practical acquisition of reflectance parameters is still a difficult problem. Even more so for spatially varying or anisotropic materials, which increase the number of samples required. In this paper, we present an algorithm for acquisition of spatially varying anisotropic materials, sampling only a small nu...

The color of 24 commercially available denture resins was determined visually with Munsell color tabs and by reflection spectrophotometry. Correlation between Munsell and spectrophotometric data was found. The resins characterized for Black patients had a higher degree of specular reflectance and were more opaque than resins for Caucasians.

The effects of thickness, background color, specular reflection, and surface roughness on the color of five commercial restorative resins were studied by reflection spectrophotometry. As thickness increased, values of luminous reflectance and excitation purity increased for a black background but decreased for a white background. Opacity increased dramatically as thickness increased from 1.3 to...

We measured radiance distributions for black lining cloth and copper gauze using the convenient technique of wrapping the materials around a circular cylinder, irradiating it with a parallel light source and collecting the scattered radiance by a digital camera. One family of parallel threads (weave or weft) was parallel to the cylinder generator. The most salient features for such glossy plane...

Microscopic hyperspectral imaging technology is a potential non-destructive and non-contact method for colour measurement of micrometre-sized textile fibres. However, specularity on the fibre surface can distort accurate information affect accuracy measurement. This paper proposed specular-constrained sparse approximation (SCSA) specular-diffuse reflection separation from images wool First, spe...