CS488 - Introduction to Computer Graphics - Lecture 23

Comments and Questions

  1. End of course topics

Natural Phenomena

The General Idea

Many substances we want to include in our scenes have complex surface properties.

How it's done ab initio

  1. Build a model, often a simulation, as close to the underlying science as possible. E.g. colours of cloth
  2. Generate a full range of results from the model by varying its parameters. E.g. cloth dying
  3. Reduce the parameters
  4. Build a modelling interface that allows the modelling to "paint by numbers".

Paritioned Rendering

This is an example of a general technique called partitioned rendering.

  1. In nature the full simulation is performed during the rendering process.
  2. For computer graphics we partition the rendering into two parts
    1. an off-line calculation that leaves us a simplified model with parameters
    2. an on-line calculations tha renders from the model as if the simulation were being performed on-line.

Partitioned rendering is very common in computer graphics


Human Skin

Physical picture

Mix them by Kubelka-Munk

Get skin parametrized by three concentrations:

Encapsulated in a spectral reflectance function. But there are more things to add, such as


Subsurface Scattering


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