Shadow Algorithms Data Miner

Preface, Motivation, and Objective xvii

Variable Definition

P Point (x, y, z) to be shaded.

ˆ

N

Unit normal (x, y, z)atpointP.

L Point light source position (x, y, z), or

pointsampleonanextendedlightsource.

ˆ

L Unit light vector from P to L;thus,

ˆ

L =

L−P

∥L−P∥

(note that a directional (innite) light is only dened by

ˆ

L).

C Camera position (x, y, z).

ˆ

V Unit view vector (x, y, z)forcameraatC pointing at P;

thus,

ˆ

V =

P−C

∥P−C∥

.

Table 1. Notation used in this book.

ˆ

N

ϕ

o

θ

o

θ

i

ϕ

i

ˆ

T

ˆ

V

ˆ

B

ˆ

L

P

Figure 2. Illustration of the commonly used variables.

Spaces

When rendering a 3D scene in an image, as well as when computing shadows,

various stages of the process can be accomplished ...