Out‐of‐Core Simplification and Crack‐Free LOD Volume Rendering for Irregular Grids
Zhiyan Du, Yi‐Jen Chiang · Computer Graphics Forum · 2010
Abstract We propose a novel out‐of‐core simplification and level‐of‐detail (LOD) volume rendering algorithm for large irregular grids represented as tetrahedral meshes. One important feature of our algorithm is that it creates a space decomposition as required by I/O‐efficient simplification and volume rendering, and simplifiesboththeinternalandboundaryportions of the sub‐volumes progressively by edge collapses using the (extended) quadric error metric, while ensuring any selected LOD mesh to becrack‐free(i.e., any neighboring sub‐volumes in the LOD have consistent boundaries, and all the cells in the LOD do not have negative volumes), with all computations performed I/O‐ejficiently. This has been an elusive goal for out‐of‐core progressive meshes and LOD visualization, and our novel solution achieves this goal with atheoretical guaranteeto be crack‐free fortetrahedralmeshes. As for selecting a desirable LOD mesh for volume rendering, our technique supportsselective refinementLODs (where different places can have different error bounds), in addition to the basicuniformLODs (where the error bound is the same in all places). The proposedscalar‐value rangeandview‐dependent selectionqueries for selective refinement are especially effective in producing images of the highest quality with a much faster rendering speed. The experiments demonstrate the efficacy of our new technique.