Ray Tracing for Global Illumination

Ray Tracing for Global Illumination

By Nelson Max
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Ray Tracing for Global Illumination episodes

  • Hierarchical Radiosity
    Lecture 26 discusses multiple reflections in precomputed radiance transfer and hierarchical radiosity, with subdivision oracles and the push-pull method for shooting and gathering radiosity. (At 12 minutes, the factor of y_i(Psi_k) is not needed in the integral, since the integral for computing t_i^0 already involves that factor. The word "octtree" should be replaced many times by "quadtree", since we are doing quadtree subdivision.)
    53 min
  • Ambient Occlusion
    Lecture 25 discusses ambient occlusion, precomputed radiance transfer, spherical harmonics, and computing the coefficients of the spherical harmonics series by ray tracing. (At 24:24 minutes, the relation should read z^2 = 1 - x^2 - y^2, not z^2 = 1 - x^2 + y^2.)
    50 min
  • Extinction and Scattering Coefficient
    Lecture 24 defines the extinction coefficient, scattering coefficient and albedo, derives the differential equation for radiance transport in a participating medium, shows how to create a photon map for a participating medium and how to integrate its inscattering along a viewing ray. (At 12 minutes "d omega" should be "d omega' ". The end of the bidirectional path tracing discussion should have included a factor of the transparency along the dotted line.)
    41 min
  • Photon Mapping
    Lecture 23 describes photon mapping on surfaces and extinction as well as transparency in participating media. (At 37:40 minutes, the fraction that gets through should be 1 - sigma_t*ds, not 1 - sigma_t.)
    50 min
  • Point-to-Polygon Form Factor
    Lecture 21 gives an analytic formula for an unobstructed point-to-polygon form factor. (At 9:43 minutes, "Sum beta*cos(alpha)" should be "(1/2) Sum beta*cos(alpha)" since the area of a sector of a unit circle is half the subtended angle. In the formula for cos(alpha), V1 cross V2 must be normalized, because it it not a unit vector, even if V1 and V2 are.) Multipass global illumination methods are explained in terms of L D S G and E notation.
    49 min
  • Refraction
    Lecture 20 gives the derivation of Snell's law for the refracted direction and discusses Fresnel's law for refracted energy fraction. (The rest of the energy goes to transmission). It also discusses pros and cons of the radiosity and path tracing methods and combining the best of both methods using final gathering as well as the Nusselt analog for unobstructed point to polygon form factor.
    50 min
  • Global Lines
    Lecture 19 explains the hemicube estimates for patch-to-patch form factors for "Galerkin" piecewise constant radiosity and for vertex-to-vertex form factors for "point collocation" piecewise linear radiosity. It also continues the proof that the global lines form factor computation is correct. (At 26:48 minutes, "cos(theta) = length/1" should be "cos(theta) = 1/length" and at 40:40 minutes, the sound track saying "is two at these other vertices" should say "is zero at these other vertices").
    51 min

About Ray Tracing for Global Illumination

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This course covers techniques for realistic computer graphics rendering that consider global illumination, that is, light from light sources bouncing multiple times on object surfaces in the scene…