Sharat Chandran Computer Science and Engg. Dept. IIT, Powai Mumbai, INDIA 400 076 sharat@cse.iitb.ac.in |
Mayur P. Srivastava Computer Science and Engg. Dept. IT BHU Varanasi, INDIA 221 005 mayur_prakash@rediffmail.com |

Our solutions complements existing solutions, and are for the restricted subset of dynamic environments when new light sources appear, but the scene geometry does not change. We design and implement a simple solution based on hierarchical radiosity, and contrast it with an alternate solution.

For simplicity, the methods assume that the source of light appear on one of the preexisting patches.

This enables simpler, interactive algorithms, and at the same time provides solutions for a reasonable subset of situations in dynamic environments in global illumination. Our solutions work in the context of the hierarchical radiosity (HR) algorithm. The patches corespond to roots of quadtrees.

The algorithm refines user patches into sub patches and sets up a linear number of links.

In the general case, the light source will intersect with some of the preexisting nodes of the HR algorithm. We therefore need to further refine nodes that would not have been expanded in the original algorithm.

Although adaptive refine is fast, it can take a large amount of time if the initial scene is dense, and the input light source is highly irregular and not aligned with the patch boundaries.

An even faster algorithm is possible if one accepts a coarser approximation of the light source.

The idea here is to mark those portions of the HR nodes that get affected by the light source as in adaptive refine (AR).

The departure with AR arises when AR decided to further refine a node n that the HR algorithm does not refine.

At this point, in the third algorithm, fractional emissivity (FE) is assigned to n based on the percentage of overlap between the light source and n.

This overlap is computed using an algorithm such as Hodgman-Sutherland.

Test Scene One (Cornell Room in side view) | Test Scene Two (Office Scene) | Test Scene Three (Cornell Room in Pigeon's View) |