{'fraction_non_alphanumeric': 0.023786869647954328, 'fraction_numerical': 0.003805899143672693, 'mean_word_length': 5.375757575757576, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Volume decimation of irregular tetrahedral grids

Rendering highly complex models can be time and space prohibitive, and decimation is an important tool in providing simplifications. A decimated model may replace the original entirely or provide level-of-detail approximations. We present and evaluate, quantitatively and qualitatively, methods for rapidly decimating volumetric data defined on a tetrahedral grid. Results are compared using both direct volume rendering and isosurface rendering. A mass-based and a density-based decimation error metric are compared, and the mass-based metric is found to be superior. Grid surface vertices are decimated using a geometric error metric, as well as one of the data-based error metrics. Images produced using direct volume rendering and isosurface extraction on grids that are decimated approximately 80% are nearly indistinguishable from similar images using the non-decimated grids, and even at 95% decimation, the rendered images have few artifacts. Rendering speed-up depends upon the renderer used.