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Forward Simulation

I simulate the light intensity field at the pool floor using ray tracing. For our purposes, we assume that light travels with an infinite velocity; i.e. any ray refracting through the water surface will project instantly onto another point on the floor. If multiple rays for any reason converge at a point before reaching the floor, they form a refracted caustic (Shah et al., 2007).

This simplistic view of the experiment has received considerable attention in the field of computer graphics. Shah et al. (2007), for example, introduce a real-time technique for rendering caustics from reflective and refractive surfaces. Ray tracing techniques have a major deficiency, in that we need an infinite number of rays to simulate a realistic distribution of light. This shortcoming is discussed by Watt (1990) who suggests using beam tracing as an alternative. The vast majority of the techniques developed in computer graphics, however, are developed for a 3D space having point light source(s), polygonal objects, and a single observation point.

Our simplified case inherits only a minor subset of the wide range of techniques used in computer graphics. To start, we will not have an observer point, and therefore do not need to ray trace from the pool floor to the observer point. Also, we have only a single smooth surface of moderate relief, and the incident light direction is limited to rays arriving from above the surface. In other words, we have an unique refraction from each point on the surface. Because we have moderate topology in the water surface, we will assume that the refracted rays do not re-intersect the water surface.



Subsections
next up previous [pdf]

Next: Surface Representation Up: Ray tracing modeling and Previous: Introduction

2009-04-13