A FAST ALGORITHM FOR CALCULATION OF RADIATIVE ENERGY DISTRIBUTIONS RECEIVED BY PINHOLE IMAGE-FORMATION PROCESS FROM 2D RECTANGULAR ENCLOSURES

In the fast algorithm, the total energy received by pinhole image-formation elements is divided into two parts: the direct part and indirect part. The indirect energy was related to the direct part, and the latter was calculated through a concept of effective angle factor for image formation. For 2-D systems filled with emitting, absorbing, isotropically scattering medium and surrounded by diffusely reflecting wall surfaces, the results through using the fast algorithm approached the statistical average values of those calculated using the Monte Carlo method, and the computation time can be nearly 50 times faster.