10.2 Criticality graph, zones, and fast rendering.

For rendering the iso-surfaces at a fixed threshold, we need only input the zones of the criticalities that contain these boundaries. In fact if we are given iso-value $\tau$, we can input only the criticalities p, with parent q, that satisfy $\delta(p) \geq \tau > \delta(q)$. From p we can quickly find a threshold crossing, searching within the zone. We can then (using SpiderWeb) only input those points on hypercubes containing hits. Obviously, whenever a hit occurs on a cube edge, all cubes sharing the edge also have hits. This is important as researchers have been concerned with preprocessing the data so that excessive I/O is not performed. One could further organize the readings in a zone using an oct-tree, an interval-tree, or a similarly appropriate data structure.