Hardware-assisted visibility sorting for unstructured volume rendering

• Published in: IEEE transactions on visualization and computer graphics 2005-05, Vol.11 (3), p.285-295
• Main Authors: Callahan, S.P., Ikits, M., Comba, J.L.D., Silva, C.T.
• Format: Article
• Language: English
• Subjects: Algorithms; Artificial Intelligence; Cluster Analysis; Computational fluid dynamics; Computer Graphics; Equipment Design; Equipment Failure Analysis; Fragmentation; Fragments; Graphics; graphics processors; Hardware; Image Enhancement - instrumentation; Image Enhancement - methods; Image Interpretation, Computer-Assisted - instrumentation; Image Interpretation, Computer-Assisted - methods; Image segmentation; Imaging, Three-Dimensional - instrumentation; Imaging, Three-Dimensional - methods; Index Terms- Volume visualization; Information Storage and Retrieval - methods; Numerical Analysis, Computer-Assisted; Pattern Recognition, Automated - methods; Prototypes; Rendering; Rendering (computer graphics); Reproducibility of Results; Sampling methods; Sensitivity and Specificity; Signal Processing, Computer-Assisted - instrumentation; Sorting; Streaming media; Studies; User-Computer Interface; Visibility; visibility sorting; Visualization
• ISSN: 1077-2626; 1941-0506
• DOI: 10.1109/TVCG.2005.46

Harvesting the power of modern graphics hardware to solve the complex problem of real-time rendering of large unstructured meshes is a major research goal in the volume visualization community. While, for regular grids, texture-based techniques are well-suited for current GPUs, the steps necessary for rendering unstructured meshes are not so easily mapped to current hardware. We propose a novel volume rendering technique that simplifies the CPU-based processing and shifts much of the sorting burden to the GPU, where it can be performed more efficiently. Our hardware-assisted visibility sorting algorithm is a hybrid technique that operates in both object-space and image-space. In object-space, the algorithm performs a partial sort of the 3D primitives in preparation for rasterization. The goal of the partial sort is to create a list of primitives that generate fragments in nearly sorted order. In image-space, the fragment stream is incrementally sorted using a fixed-depth sorting network. In our algorithm, the object-space work is performed by the CPU and the fragment-level sorting is done completely on the GPU. A prototype implementation of the algorithm demonstrates that the fragment-level sorting achieves rendering rates of between one and six million tetrahedral cells per second on an ATI Radeon 9800.