The most important aspect of rendering light accurately is defining the geometry and the materials properties accurately - in REAL WORLD units. Compter graphiscs techniques and short cuts are to be avoided at all cosats. This page of the {Day}light Rendering wiki is dedicated to the provision of physically accurate materials properties for use in simulation programs. The aiom is not to list properties but toi define what are the minimum requirements for publication of materials properties.

The key underlying concept of these material properties listings is the notion, borrowed from the Art world of PROVENANCE. No data about the reflectivity or the transmissivity of a material should be accepted for use in a rendering program unless it has the following supporting information:

• name of the laboratory that produced it
• name and contact details of the person who did the test
• documentation of the laboratory's record as a user of the test (publications in reputable journals etc)
• documentation of the test itself (again - reputable publications)
• documentation of the variability of the result under standard conditions - error bar in the readings plus likely in the field variability

This Metadata should be provided with every piece of data entered into the simulation program.