Research And Application Of Direct Volume Rendering Algorithm Based On Gpu

Direct volume rendering of complex3D volume data can be efficiently carry outwith its high rendering speed and flexibility to meet the users. The direct volumerendering result is intuitive and solid, but often lacks certain realism, which is difficultto meet the growing visual requirements of users.This dissertation is based on the above background, to improve real-time realisticrendering algorithm to enhance the realism while guarantee the real time rendering. Wechoose typical splatting algorithm for study. By learning the theory of harmonic light,we improved the original splatting algorithm both on light simulation and real-timerendering to make the algorithm render high quality image in real-time on GPU.During light simulation, we’ve designed a suitable illumination model which hasconsidered reflection, and shadow. When simulating the specular reflection, amathematical models based on experience is used to improve computational efficiencywhile taking advantage of the block information contained in diffuse reflection toimprove the realism of the results. Spherical harmonic decomposition of functions in theillumination model is done in the pre-computation stage which greatly reduces thecomputational complexity of real-time lighting.In real-time rendering, we have designed a novel method to solve thealiasing problem. We regard the view point as an imaginary light source and reconstructthe light intensity to decide whether the splat to be blended. Meanwhile, byreconstruction using SH function under the direction of real light, we carried out lightsimulation to assure a real-time and realism render image.In order to accelerate the splatting algorithm, we transfer the harmonicreconstruction into GPU.The experiment result has proved that our method can be applied to the real-timerealism rendering of complex model. We have achieved a satisfied anti-aliasing imageincluding shadow, reflection under the changing light.