Volume rendering is a technique for visualizing 3D arrays of sampled data. It has applications in areas such as medical imaging and scientific visualization, but its use has been limited by its high computational expense. In this thesis, two algorithms are presented to achieve interactive visualization for medical imaging. First, an improved splatting algorithm is presented that deals with uneven spacing between adjacent layers in volume data. Depending on the spacing between the layers in the volume data and the viewing angle in the visualization process, the footprint for the splatting operation takes different shapes. In previous approaches, a huge look-up table is used to store a finite set of precomputed footprints. During a visualization process, a footprint from the look-up table that gives the minimum error will be used as an approximation. The new algorithm eliminates the need for the look-up table by using a flexible method to generate accurate footprints for arbitrary layer spacing and viewing directions.; Second, a scan converting mapping algorithm is presented. This algorithm combines a standard polygon scan converting algorithm with a texture mapping algorithm. It achieves a near real-time performance which is comparable to the best existing method, e.g., the shear-warp algorithm--a run-length coding based method. Furthermore, a simple masking technique is proposed which accelerates the scan converting mapping algorithm by skipping the empty space inside a volume. Since the scan converting mapping algorithm re-samples the volume data, the arbitrary spacing between layers is automatically handled.
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