View-independent Modeling of Lighting Systems by Local Estimations of the Monte Carlo Method

Computer-aided designing of lighting systems has been remaining of relevance for more than ten years. The most popular CAD packages for calculating lighting systems, such as DIAlux and Relux, are based on solving the radiosity equation. By using this equation, the illuminance distributions can be modeled, based on which the standardized quantitative lighting characteristics can be calculated. However, the human eye perceives brightness, not illuminance. The qualitative parameters of lighting are closely linked with the spatial-angular distribution of brightness, for calculation of which it is necessary to solve the global illumination equation. An analysis of the engineering matters concerned with designing of lighting systems points to the obvious need for a so-called view-independent calculation of lighting scenes, which means the possibility to visually represent a scene from different positions of sighting (a camera). The approach based on local estimations of the Monte Carlo method as one of efficient techniques for solving the global illumination equation is considered, and an algorithm for view-independent modeling based on the local estimations method is presented. Various algorithms for solving the problem of searching the intersection for the casted beams from a light source with the studied illumination scene are investigated.

Integral equations for free-molecule ow in MEMS: recent advancements

We address a Boundary Integral Equation (BIE) approach for the analysis of gas dissipation in near-vacuum for Micro Electro Mechanical Systems (MEMS). Inspired by an analogy with the radiosity equation in computer graphics, we discuss an efficient way to compute the visible domain of integration. Moreover, we tackle the issue of near singular integrals by developing a set of analytical formulas for planar polyhedral domains. Finally a validation with experimental results taken from the literature is presented.

Realistic Projection on Casual Dual-Planar Surfaces with Global Illumination Compensation

Projectors are deployed in increasingly demanding environments. The fidelity of the projected image as seen by a user is compromised when projectors are deployed in dual-planar environments (e.g. corner of a room or an office cubicle), thereby diminishing the richness of the user experience. There are many reasons for this. The focus of this paper is to compensate for the global illumination effects due to inter-reflection of light. In the process we also correct geometry distortion. Our system is built from off-the-shelf components and easily deployable without any elaborated setup. In this paper, we describe two complementary methods to compensate for global illumination effects in dual-planar environments. Our methods are based on the systematic adaptation and interpretation of the classical radiosity equation in the image domain. The technique neither assumes nor computes 3D scene geometry, relying on an implicit inference. The system is calibrated in an off-line mode once; in our first method, corrected images and video are computed in real time, and in our second method, a richer scene is offered with a modest increase in computational time. The corrected images when projected have better contrast and are more appealing to the user.

Optimal Shape Design for Radiative Enclosures Using NURBS

This article presents an optimal shape design methodology for diffuse-walled radiant enclosures. In this study, the shape of the enclosure is parameterized by means of non-uniform rational B-spline (NURBS) surfaces, and their control points represent the design variables. The enclosure geometry is discretized by choosing the parameters of NURBS surfaces as generalized curvilinear coordinates, and the radiosity equation is solved using the infinitesimal-area analysis technique developed by Daun and Hollands [1]. The simplified conjugate-gradient method (SCGM) is used as the optimization method to obtain the optimal shape and adjust the design variables intelligently. The methodology is demonstrated by optimizing the shape profile of a cavity with the objective of enhancing the apparent emittance.

Adjoint Equations and Error Measure in Radiative Heat Transfer With Diffuse Reflection

In this paper, we develop an application of the importance equation (which is an adjoint equation of the radiosity equation) in the case of isothermal, diffuse surfaces. We recall the formulation of the radiosity equation, in function of the nature of the boundary condition (either known temperature or fixed radiative heat flux). We define the importance as the quantity dual to radiosity. We explain how these equations can be used after the resolution of a radiative heat transfer situation, as a post processing step, to establish the accuracy of each individual radiative link between the active faces of a tri-dimensional surface geometrical model.