On-the-fly simplification of large iso-surfaces with per-cube vertex modifiability detection

Marching Cubes based iso-surface extraction is widely used for data visualization. However, the increasing size of volume sets has made extracted iso-surfaces difficult to manipulate, and applying out-of-core simplification on them is considerably slow. We present an on-the-fly simplification algorithm for out-of-core iso-surfaces generated by Marching Cubes based extraction. Our algorithm shifts between extraction and decimation during the processing of volume sets, and never stores the entire extracted iso-surface in the main memory. The key of our algorithm is that we exploit the extraction pattern of Marching Cubes to determine when the mesh operator can be applied on certain generated vertices. This enables the decimation to be applied after any specified number of triangles are extracted. It also provides a framework for on-the-fly processing of large iso-surfaces. Our algorithm is more efficient than cascading out-of-core extraction and simplification, while providing high simplification quality comparable to in-core algorithms.