Integrated Irregular Volume Decompression and Out-of-Core Iso-Surface Extraction

Volume data sets tend to grow bigger and bigger as modern technology advances, thus imposing a storage constraint on most systems. One general solution to alleviate this problem is to apply volume compression on the volume data sets. However, as volume rendering is often the most important purpose why a volume data set was generated in the r st place, we must take into account how a volume data set could be efciently rendered when it is stored in a compressed form. Our previous work [YMC00] has shown that it is possible to perform a on-the-y direct volume rendering from irregular volume data. In this work, we further extend that work to demonstrate that a similar integration can also be achieved on iso-surface extraction and volume decompression for irregular volume data. In particular, our work involves a data set decomposition process, where instead of a coordinate-based decomposition used by conventional out-of-core iso-surface extraction algorithms, we choose to use a layer-based structure. Each such layer contains a collection of tetrahedra whose associated scalar values fall within a specic range, and is compressed independently to reduce the storage requirement. The layer structure is particularly suitable for out-of-core iso-surface extraction, where the required memory exceeds the physical memory capacity of the machine that the process is running on. Furthermore, with this work, we can perform on-the-y iso-surface extraction during decompression, and the computation only involves the layer that contains the query value, rather than the entire data set. Experiments shows that our approach could improve the performance up to ten times when compared with the results based on the traditional coordinate-based approaches.