1. Atmospheric Effects Cameron Rivers B. Sc. Computer Science in a Global Illumination Engine

2. Traditional ray tracing engines do not cover, or greatly simplify, the effects temperature changes have on light transport. There does not currently exist a commonly accepted method for describing this contribution. Useful to large-scale, production-quality rendering engines. © Cornell University

3. Research Started with a direct illumination ray tracer. Added global illumination techniques to more accurately represent light physics. Implemented light ray refraction based on changes in air temperature.

4. Global Illumination Direct Lighting Ray Tracing Indirect Lighting Photon Mapping

5. Image rendered using direct lighting only.

6. Image rendered using indirect lighting only.

7. Image rendered with both direct and indirect lighting.

8. Refraction Medium 1 Medium 2

9. Atmospheric Refraction Temperature of air decreases/increases with distance from object. Index of refraction changes with temperature.

10. Background Information Existing global illumination engines Pixar’s RenderMan Plane, toxic Mirage simulators

11. Solution Determine max falloff distance of temperature influence. Create intermediate objects offset by a step size based on the max falloff distance. Check for intersection against these objects. If an intersection occurs, refract the light ray by the index of refraction of the intermediate object.

12. Results Evolution of engine, showing the addition of global illumination through photon mapping and temperature intersection.

19. 2,100,624 rays created 1,160,895,281 intersection tests 1029 minutes 7.848 seconds to render

22. Results Analysis Layered modeling feasible Accurate index of refraction versus temperature falloff model Needs more work

23. Future Work Increasing performance Spatial subdivision Increasing quality Adaptive super-sampling Normal smoothing Physics solver

24. Conclusion Questions?