Date submitted: January 18, 2013
Code emailed: January 18, 2013
Fig. Color dispersion by a prism of V-number 10
Our target is to render color dispersion effects, including refracted rainbows and camera color aberration. This is achieved by simulating rays of different wavelengths integrating radiance over them. We also provide a common dispersion measure for user to customize the glass material and realistic camera lens.
We modified PBRT system to render one spectral value of one sampled wavelength in a ray tracing process. The key algorithm is the conversion between RGB and sampled spectral values, which has already been implemented in PBRT. The input colors like lights and materials are sampled at current chosen wavelengths. The ray traced and shaded values are converted back to colors and integrated.
Our new system supports direct lighting, path tracing, and photon mapping, described as follows:
To calculate the refractive index of each wavelength, we fit the refractive index to wavelength curve by the two-term Cauchy's equation
We had tested some of the lens in homework 2. The D-Gauss lens set minimizes chromatic aberration well. The Telephoto lens set zooms far, but suffers from this artifact.
Fig. Color dispersion by a sphere
Fig. Color dispersion by a cylinder
Fig. Spectral rendered D-Gauss lens
Fig. Color aberration of telephoto lens
 Physically Based Rendering: From Theory to Implementation, Matt Pharr and Greg Humphreys, 2nd ed, Morgan Kaufmann, 2010
 gpusppm, code from "Stochastic Progressive Photon Mapping, T. Hachisuka and H. W. Jensen, ACM Transactions on Graphics (SIGGRAPH Asia 2009), 2009"
 Craig Kolb, Don Mitchell and Pat Hanrahan, A Realistic Camera Model for Computer Graphics, SIGGRAPH 1995
 Iman Sadeghi, Adolfo Muñoz, Philip Laven, Wojciech Jarosz, Francisco Seron, Diego Gutierrez, Henrik Wann Jensen. Physically-based Simulation of Rainbows. ACM Transactions on Graphics (Presented at ACM SIGGRAPH 2012), 31(1):3:1–3:12, February 2012