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Final Project Proposal: LeeHendrickson, RyanSmith
Our goal is to render a lava flow or a molten material such as steel. These materials exhibit black-body radiative characteristics that cause their surfaces to be emmissive. Furthermore, the particular features of such a surface have a somewhat chaotic/irregular look to them that lends itself to be modeled through procedural methods. These two concepts are intrinsically related, as the surface of the material changes (due to cooling over time, or structural deformation due to flow) so does its emmissive characteristics - we wish to model the system so as to gainfully exploit this relationship.
Visually, an active lava flow or a stream of molten steel is very compelling, as it is both dramatic and unique. This is not something a person has everyday exposure to, and as such a certain sense of excitement/wonderment is produced in the viewer by these phenomenon.
On a technical side, PBRT currently only supports "traditional" light sources such as a point light, an area light, or an environment map. Adding support for black body radiators opens the door to many other interesting light sources such as fires.
We would also like to enrich PBRT's procedural generation algorithms with one having some distinctive physical basis. Since the temperature of a molten material has some direct relationship with time (as it flows and possibly cools), parameterizing the generating algorithms with a time factor could lead to the production of some eye-catching animations.
Key Technical Challenges
- Black body radiation.
- Computing (physically) correct emissive characteristics of material (based on temperature).
- Varying between the emissiveness of the black body at high temperatures and a possibly more traditional BRDF at low temperatures in a continuous and plausible fashion.
- Actually lighting the environment according to the calculated emissiveness of the black body (photon mapping?)
- Procedural generation of surface features.
- Designing a procedural algorithm to generate a visually appealing and plausible surface temperature (and thus emissive characteristic) for the flow. This algorithm should be parameterized such that other information (such as temperature of the area directly below the surface) can be taken into account to give rise to a more physically correct surface.
- Possibly in later stages using a procedural algorithm to generate the geometry of the material itself rather than a fixed model.
- The procedurally generated surface features should be able to be fed to the black body radiation algorithm such that emissiveness is directly related to those surface features.
- Modeling an appropriate environment.
- To be able to visually recognize that the flow is a black body radiator there must be at least some objects in the environment that can realistically reflect the emitted light.
- However, given the time frame of the project this must be balanced with the need to otherwise keep the scene as simple as possible.
Outline of Approach
Given the different components of the project there is a natural delineation of work across technical challenges 1 and 2 above. The focus will be on rapidly prototyping each component in PBRT, with Ryan concentrating on black body radiation, Lee on procedural generation methods, and both on modeling (most likely the geometry of the scene will be created in 3dsmax or Maya). Once these proof-of-concepts are completed a more full fledged implementation will begin that integrates the two subsystems into one cohesive unit to create the final rendered image.