关键词: 图形处理器加速, 层析图像, 光线投射, 体绘制, 传输函数

Abstract: In order to overcome the rendering drawbacks of traditional algorithms that cannot be interacted fluently with the user and have a big time consumption and single rendering result, a ray casting algorithm based on Graphics Process Unit (GPU) was proposed to be used for the real-time volume rendering of medical tomographic images. Different rendering effects can be switched quickly by the proposed algorithm. Firstly, medical tomographic images were read into the computer memory to construct voxels. Afterwards, properties (interpolating, shading and light) of the corresponding voxels were set. The transfer functions of color and opacity were designed to display different organs and tissues. Finally, the volume data were loaded and the ray casting algorithm was executed by GPU. The experiments show that the rendering speed of the proposed algorithm can reach 40 frames per second, which satisfies the clinical application. On the aspect of rendering quality, jags produced in the process of interaction because of resampling on GPU are apparently lower than the ray casting algorithm on CPU. The time consumption of CPU-based ray casting algorithm is about 9 times that of the proposed algorithm.

Key words: Graphics Process Unit (GPU) acceleration, tomographic image, ray casting, volume rendering, transfer function