ACCELERATING TECHNIQUES IN VOLUME RENDERING OF IRREGULAR DATA

Volume rendering of irregular data has become a challenging research t opic in the area of scientific visualization in recent years. In compa rison with regular data rendering, irregular data volume rendering fac es many new problems. Because cells in an irregular Volume have variou s shape and size, volume rendering by the raycasting method has more d ifficulty in calculating the intersection between rays and cells, and the projection method has even greater trouble in queuing up cells, in particular concave cells. To accelerate volume rendering of irregular data, this paper presents a hybrid method which possesses the advanta ges of both raycasting and projection methods. The main strategy in th e method is using a polygon scan conversion algorithm in 3-D space to set up a ray path with high efficiency, and by establishing intersecti on links to allow the operation of color composition to be locally con ducted on-the-fly. As a result, it is possible to produce high quality images without the requirement of the heavy task for cell queuing up and complex ray intersection calculation. (C) 1997 Elsevier Science Lt d.