3D graphics eBook - Course Materials Repository

Silhouette edge 189
External links
• http:/ / wheger. tripod. com/ vhl/ vhl. htm
Spectral rendering
In computer graphics, spectral rendering is where a scene's light transport is modeled with real wavelengths. This
process is typically a lot slower than traditional rendering, which renders the scene in its red, green, and blue
components and then overlays the images. Spectral rendering is often used in ray tracing or photon mapping to more
accurately simulate the scene, often for comparison with an actual photograph to test the rendering algorithm (as in a
Cornell Box) or to simulate different portions of the electromagnetic spectrum for the purpose of scientific work.
The images simulated are not necessarily more realistic appearing; however, when compared to a real image pixel
for pixel, the result is often much closer.
Spectral rendering can also simulate light sources and objects more effectively, as the light's emission spectrum can
be used to release photons at a particular wavelength in proportion to the spectrum. Objects' spectral reflectance
curves can similarly be used to reflect certain portions of the spectrum more accurately.
As an example, certain properties of tomatoes make them appear differently under sunlight than under fluorescent
light. Using the blackbody radiation equations to simulate sunlight or the emission spectrum of a fluorescent bulb in
combination with the tomato's spectral reflectance curve, more accurate images of each scenario can be produced.
References
External links
Cornell Box photo comparison (http:/ / www. graphics. cornell. edu/ online/ box/ compare. html)