Shadow Algorithms Data Miner

1.5. Considerations for Choosing an Algorithm 21

1.4.3 Advanced Reflection Models

Direct shading is computed only when the surface is facing light (

ˆ

N ⋅

ˆ

L > 0) and

is not in shadow. However, even under direct illumination, shadowing can occur

within the reection model itself.

When the bumps are smaller and denser over a surface, such that many bumps

t within a pixel, neither the bumps nor the shadows can be perceived. However,

the reection of light behaves dierently as bumps cast shadows on some areas and

not on others. is phenomenon should be captured by the local reection model.

In advanced reection models, such as anisotropic reection models, ...