关键词: 直接体绘制, 保留上下文, 光线投射算法, 焦点, 转换函数, 高斯函数

Abstract: In direct volume rendering, it is very difficult to remove or suppress less important parts of a scene to reveal Region Of Interesting （ROI）. In order to enhance the region of interest, a context-preserving volume rendering is presented, using the spatial relationships between the sampling points and the focus （center points of ROI）. A focus is located manually to determine ROI. Then the spatial information including the distance between sampling points and focus, the angular separation is gathered and fed to a pre-defined Gaussian-attenuation function. Finally, this attenuation function is used to control the composition of the rays. The proposed method is evaluated on CT head data. The experimental results show that occluding objects are rendered sparsely or suppressed entirely, at the same time, the ROI is visually emphasized and preserves the clear shape cues of background and good human-computer interaction.

Key words: direct volume rendering, context-preserving, ray-casting algorithm, focus, transfer function, Gaussian function