Light and Lighting Models

Question 1

Radiant Power

Answer 1

The Amount of light hitting a surface during a set period of time

Question 2

Radiant Intensity

Answer 2

Amount of power traveling from a source in a certain direction

Question 3

Radiance

Answer 3

Power arriving or leaving a surface, per unit solid angle, and per unit of projected area

Question 4

Spectral Distribution of Light

Answer 4

Colour attributes of a material in terms of reflectance and transmittance

Question 5

BSSDF

Answer 5

Bidirectional surface scattering distribution function

Question 6

Lambertian

Answer 6

A diffuse lighting model approximation

Question 7

Diffuse Lighting

Answer 7

The amount of light is independent of the viewer’s direction. Reflected light is only proportional to the angle of incidence of the light itself.

Question 8

Specular Reflection

Answer 8

Light reflected proportional to the viewer’s angle

Question 9

Specular Reflection Vector

Answer 9

R = L - 2N (L . N)
or if L is leaving the surface
R = 2N (L . N) - L

Question 10

Attenuation

Answer 10

Light fades over distance. Intensity of a light can be given by attenuation parameters c1, c2, and c3 such that the intensity received by a surface is

LightIntensity_i * (L . N) / (c1 + c2 * ri + c3 ri^2)

Question 11

Phong Illumination

Answer 11

Small phong coefficient => larger specular reflection

phi = kd + ks (R . V)^p / (N . L)