Error analysis and improvement of potential tracing algorithm for global illumination

Considering the variance bought up by approximation of radiance during the first pass, this paper presents error analysis and an improvement method for the potential tracing algorithm. With a general form of equations for importance sampling based random walks, variance analysis is given and its relationship to the error of radiance is shown. Aiming at error reduction, a computing method of alternatively solving both adjoint equations is proposed, giving a progressive refinement to both radiance and value of the required flux. Analysis of the method demonstrates a promising convergence rate with iterations.