[Real-time volume rendering based on gradient adaptive shading].

For medical image volume rendering, it is very difficult to simultaneously visualize interior and exterior structures while preserving clear shape cues. Highly transparent transfer functions produce cluttered images with many overlapping structures, while clipping techniques completely remove possibly important contextual information. To address this issue, A gradient adaptive shading based illumination model is proposed and implemented in CUDA architecture. The coefficients of ambient, diffuse and specular lighting are tuned adaptively according to gradient. The experiments show that our method is capable of preserving 3-D contextual information in medical image dataset while still show clear boundaries with real-time interactive speed.