BSP Trees and Photon Mapping

[ LiB ]

BSP Trees and Photon Mapping

It seems possible to build a leafy BSP tree instead of using the KD Tree to store and retrieve photons for a game. For example if you built a leafy BSP tree you can create a convex hull ( cells ) of where polygons are located. See Figure 14.14.

Figure 14.14. A room of cells.

This means you build the photon map as you build the BSP tree and store the photons in each leaf of the tree. Figure 14.15 shows a room of cells.

Figure 14.15. The photons contained at each polygon ver tex in the subdivided cell .

The list of photons would be stored in each leaf spatially divided. This would be the perfect candidate for a PVS ( potentially visible set) system where you can build and render each vertex of a triangle (using the real-time technique) for each frame based on the current cells that are visible. See Figure 14.16.

Figure 14.16. The potentially visible set sys tem processes the pho- tons in the cells that are required for visibility.

This would definitely shorten the rendering time for a game and manage the data in a better fashion.

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