A Flexible Framework

A framework for volume tracing [Mai99] can be split into a number of distinct building blocks. It is essential that the interfaces between these blocks are accurately defined, so that they can interact smoothly and efficiently. The basic building blocks can be identified as

• density functions
• transfer functions
• phase functions
• participating material

Additionally, the framework should also meet the following design criteria:

• Seamless integration into an existing rendering system
• Assignment of participating media to objects of arbitrary topology
• Participating materials have to handle arbitrary combinations of absorption, emission and scattering functions
• Absorption-, emission- and scattering-functions have to handle arbitrary combinations of transfer functions
• Transfer functions may be based on arbitrary combinations of density functions
• Density functions may be based on arbitrary types of data
• Standardized interfaces (i.e. procedural density functions and volume data sets should have the same interface)
• Modularity (adding new types of functions without interfering with the rest of the framework).