一种立体光线跟踪的加速算法  

AN ALGORITHM FOR ACCELERATING STEREOSCOPIC RAY TRACING

作　　者：张萍[1] 孟宪奇[1] 莫蓉[1] 

机构地区：[1]西北工业大学CAD/CAM研究中心,西安710072

出　　处：《计算机学报》1999年第7期763-767,共5页Chinese Journal of Computers

摘　　要：基于立体视图相关性和景物对双眼的可见性变化规律提出了一种扫描线分段算法，利用对扫描线的特征分段减少单眼可见景物和景物空白的重复计算，使右图生成效率明显提高；同时考虑光亮度的视图差异，计算重投影点光亮度的视点相关分量，使立体视图的细微差别得以体现．文中还提出二代光线的间接重投影方法和“标记视点探测排序”的坏象素消除法．Stereoscopic ray tracing is one of the approaches to produce vivid images in virtual reality applications. Current methods of reprojection unnecessarily repeat calculations on scene vacancy, ignore illumination differences between stereo pair, and waste useful pixels during eliminating bad pixels. All these drawbacks reduce the speed and quality of stereoscopic ray tracing. This paper proposes an algorithm to accelerate stereoscopic ray tracing by exploring the coherence between stereo pair. The algorithm divides every scanline of stereo pair into feature segments, which associate with four types of scene content: the None eye visible, the Left eye visible, the Both eyes visible and the Right eye visible. The segments of every object projected to stereo pair are ordered, even the overlap of projections does not modify it. Reprojection method for the Both eyes visible segment is used, while calculate the other segments only once and map them respectively into both views. Much more empty pixels in right view are reduced and algorithm's efficiency is therefore improved. Illumination differences between stereo pair are small but sharply influence the stereo effect. The view dependent illumination components are recalculated to offer more dissimilarity between stereo pair. Also, an indirect reprojection method is introduced for secondary ray tracing and a “mark viewpoint feeler sort” method is proposed for better elimination of bad pixels. Both general and worst cases of this algorithm are discussed at the implementation section, and demonstrate a 20—30% acceleration over the past reprojection algorithms.

关 键 词：立体光线跟踪 重投影 算法 虚拟现实 图象识别 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]