SHIC: A View-Dependent Rendering Framework for Isosurfaces
Nan Zhang, Huamin Qu, Wei Jun Hong, Arie Kaufman · 2008
Figure 1: Illustration of our view-dependent isosurface rendering algorithm using a Lego car dataset. (a) The 241K isopoints (isovalue 120.5) extracted from a density volume. (b) The active isopoint set for the current viewpoint (Green: inherited from the previous frame, Red: newly refined or collapsed). The size of each isopoint is proportional to the size of the octree cell where it resides. (c) The isosurface constructed from the active isopoint set (Green: inherited, Red: newly extracted), 61K triangles. We present Selective and Hierarchical Isopoint Clustering (SHIC) as a framework for interactive isosurface visualization. SHIC is an octree-based vertex hierarchy where each surface component in a cell is represented by a vertex (isopoint) with encoded connectivity. We describe a novel connectivity encoding scheme, called Con-nectivity Encoding Bitmap, and two topology-preserving isopoint clustering algorithms to build the vertex hierarchy. Our framework is able to cluster surface components with up to four intersection points on a cell edge. During rendering, an incremental isosurface extraction algorithm is used to construct the isosurface dynami-cally. Events associated with vertex tree modifications and active vertices changes are unified using timestamps. Our framework is efficient, space-saving, and suitable for rendering large isosurface objects with local modifications.