Cost Analysis of a Ray Tracing Algorithm

Ray casting has become a fundamental step in many graphics algorithms es pecially in the area of global illumination Examples include using rays to calculate form factors for traditional radiosity track energy in particle tracing and trace possible transport paths in path tracing The appeal of ray casting is that it o ers a exible and intuitive way to query visibility within a scene and we expect that its popularity will continue to grow However ray casting can be an expensive operation and it is often the single most expensive part of an algorithm Thus it is important to study the costs of ray casting both to nd ways to minimize its cost and to enable the cost analysis of algorithms which utilize ray casting Unfortunately the complexity of ray casting is not very well understood A variety of acceleration schemes have been proposed by researchers but there has been relatively little analysis of these schemes Currently we have no a priori assurance about what the actual cost of these schemes will be in real world use Ray casting studies have provided useful heuristics about the costs of various schemes however to our knowledge all fall short of completeness in one of the following ways