MIP mapping based on material properties

A method for MIP mapping index texture having index values which refer to physical material proper ties, comprising the steps of:

• (a) storing a look up table having table entries defining material types, wherein each table entry has at least two material property types which are used to generate material colors;
• (b) storing at least two material property types as a function which substantially models a coefficient of conductivity;
• (c) selecting at least two texels from the index texture, each texel having index values corresponding to table entries;
• (d) averaging material property type values for each separate property type from the table entries for each selected texel, to produce an average material property value for each material property type;
• and
• (e) selecting a new material index based on the material which most closely matches the average material property values.

An index texture having texel index values and MIP maps based on physical material properties, comprising:

• (a) an index texture map which contains texel index values;
• (b) a common material table to which the texel index values refer, the common material table having at least two material property types for each material;
• (c) selecting means for selecting at least two texels from the index texture, each texel having index values and corresponding table entries;
• (d) averaging means for averaging material property type values for each property type from the at least two texels, to produce an average material property value for each material property type;
• and
• (e) search means for finding a new material index based on a material which most closely matches each average material property value for each material property type.