We present a method for modeling and rendering irregular and heterogeneous glass objects, with a specific emphasis on stained glass windows and window works often encountered in architecture from middle age to 18th century. The artisanal production of sheet glass results in glass panels displaying a vast variety of surface and volume irregularities like bubbles, irregular surface or smoothly varying refractive index, all of which contribute to the specific visual aspect of old glass. We propose to account for all the aforementioned effects in a unified framework based on signed distance functions and an analytic solution of the ray tracing equations on tetrahedral volume elements. We demonstrate how to construct an unbiased estimator for the transmitted lighting produced by such panels by using Fermat's principle and results from seismic ray theory. We use texture coordinates to map arbitrary sections of a complex glass panel onto the individual faces of a mesh, allowing the modeling and rendering of complex 3-dimensional objects composed of colored glass facets such as stained glass windows.

Catopsys is a low-cost projection system aiming at making mixed reality (virtual, augmented or diminished reality) affordable. It combines a videoprojector, a camera and a convex mirror and works in a non-specific room. This system displays an immersive environment by projecting an image onto the different parts of the room. However, the presence of an uncalibrated projector, heterogeneous materials and light inter-reflections influence the colors of the environment displayed in the room. Radiometric compensation of the projection process enables the system to reduce this problem.

In this paper we study both theoretically and experimentally some properties of classical linear systems solvers, according to the radiosity assumptions. We prove important properties for some of these solvers which allow the user to choose the best one. We then introduce a new technique so called hybridization whose purpose is to increase the convergence speed of iterative methods. It provides very efficient results for the well-known Gauss-Seidel solver. This technique has been successfully applied to both a group progressive radiosity approach and a full-matrix radiosity method which has been specifically designed for plant growth simulation. 1.