CISC 454 Goals for Test 3


Glossy reflections
  sample multiple rays
  generate random points on disk
  average the outgoing light after applying Phong to each ray
      
Shadows
  hard shadows from point light sources
    requires only a single ray to test if source is blocked
  soft shadows from area light sources
    generate random points on the area source
    how to generate UNIFORM random points on a triangle (Barycentric coords)

Antialiasing
  what does aliasing look like
  how to reduce aliasing
  jittered sampling

Bias in ray tracing
  weight of ray = factor by which ray's light is attenuated at the eye
  cut off ray after weight < threshold
  why this causes bias in the resulting image
  how to avoid bias with Russian Roulette

Illumination quantities
  solid angles
  power in Watts
  radiance in Watts/(m^2)/sr
  radiosity/irradiance
  BRDFs, albedo
  Rendering equation relating outgoing radiance to incoming radiances and BRDF

Photon Mapping
  What happens to a photon upon hitting a surface
  How to build a KD-tree
  How to look up points within a KD-tree
  How to use photons in neighbourhood of intersection point to calculate radiance

Nonuniform random numbers
  What are the PDF & CDF
  How a nonuniform random number is generated from the CDF

Volume Rendering

  Rendering equations
    exponential attenuation through a volume
    volume rendering integral
    discrete volume rendering integral
      appoximations and discretizations that are made (e.g. delta s, constant tau and C, Taylor series)

  Surface shading
    use of emission to fake light reflection
    gradient computation (intermediate, central, Sobel)
    use of negative normalized gradient with Phong

  Transfer functions
    1D: tau -> (kd, tau')

  Algorithms
    back-to-front in software
    front-to-back in software
    axis-aligned slices with 2D textures
    viewpoint-aligned slices with 3D textures

    [on Tuesday] GPU ray tracing with early termination
      store gradient in an RGB volume
      multipass rendering:
        pass 1 stores texture coords of back face of volume
        pass 2 iterates from front face to back face in small steps along ray
  

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