Fresnel Reflectance, Anisotropic Absorption, and Polarization in Rendering, to Show Crystallographic Effects
نویسنده
چکیده
A project which incrementally extends pbrt is described. Example scenes showing Fresnel reflection, isotropic absorption, and pleochroism in the gemstone tourmaline are presented. Tourmaline is typical for absorption characteristics in crystals, characteristics which often vary with wavelength and direction. Interesting color and intensity variation results from splitting incident rays, by polarization and birefringence, into ordinary and extra-ordinary rays/directions with absorption a function of wavelength and ray direction with respect to the crystalline axis.
منابع مشابه
Infrared reflectance spectroscopy on thin films: Interference effects
Laboratory simulations of processes on astronomical surfaces that use infrared reflectance spectroscopy of thin films to analyze their composition and structure often ignore important optical interference effects which often lead to erroneous measurements of absorption band strengths and give an apparent dependence of this quantity on film thickness, index of refraction and wavelength. We demon...
متن کاملCapturing Spatially Varying Anisotropic Reflectance Parameters using Fourier Analysis
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...
متن کاملRecovering Material Reflectance from Polarization and Simulated Annealing
This paper presents a novel image-based method for estimating BRDF information. The goal is to determine the dependence of the reflected radiance on the surface orientation for any given illumination direction. The proposed method consists of two stages. In the first stage, the polarization state of light reflected from an object of unknown shape is analysed using a linear polarizer and digital...
متن کاملRendering Diamonds
Fascinating colors of diamonds are generated by a combination of mechanisms including Fresnel reflection, volume absorption and light dispersion. This paper proposes an approach to unify these mechanisms to synthesize realistic computer images of diamonds. Our work is based on a composite spectral model that accounts separately for smooth components and spikes in spectra. While sufficiently han...
متن کاملAnalytic Tangent Irradiance Environment Maps for Anisotropic Surfaces
Environment-mapped rendering of Lambertian isotropic surfaces is common, and a popular technique is to use a quadratic spherical harmonic expansion. This compact irradiance map representation is widely adopted in interactive applications like video games. However, many materials are anisotropic, and shading is determined by the local tangent direction, rather than the surface normal. Even for v...
متن کامل