Geometrical Theory of Diffraction (GTD)
is an extension of geometrical optics aimed at taking into account diffraction.

We use that theory to take into account
diffraction effects in computer graphics photorealistic rendering.

In particular we simulate complex reflectance
functions from surfaces acting as diffraction gratings.

GTD can be implemented in a ray tracing
framework allowing to treat complex situations that could not be handled

by previous related work.

**A geometrical approach to modeling reflectance
functions of diffracting surfaces. **N. Tsingos

submitted to the *11th Eurographics
Workshop on Rendering 2000*.