A Combined Method Of Bidirectional Path Tracing And Photon Mapping For Photorealistic Rendering

Ray tracing is a technique for generating light paths by tracing the paths begin from light or eye, encounter with virtual objects, to simulating all the light effects in the scene. Applications include computer graphics and animation, and engineering include heat transfer. Using this technique, one can generate the most realistic picture in the world. The main challenge in ray tracing is the complexity of the geometric, scattering and the way to choose the illumination models.Based on the Maxwell’s Equation for electromagnetic, James Kajiya introduced the Rendering equation into computer graphics in1986. This equation is an integral equation under a geometric optics approximation, to simulate the lights’distribution in world. All the ray tracing ways try to solve this equation are called the physically based realistic rendering. Based on this equation, the radiance leaving a point in an object is as the same as the sum of the reflected and the emitted radiance. And the equation can be solved by iterative calculation. The most significant ways to solve the equation are some unbiased methods like path tracing and bidirectional path tracing and biased methods like photon mapping and point based rendering. All of the methods use Monte Carlo sampling. These methods are easy to use and they can lead to high quality results when we use enough samples.In this paper, we will first describe some of the important ways solve the rendering equation and compare them.Then we will give a hybrid method, which mixed the bidirectional path tracing and the photon mapping. Try to get a better result in the same time.Last we will discuss if this method can be port to GPU. We will try to make the method work on GPU and compare the results with ones generated by the traditional methods.