18 - Radiosity

Question 1

Radiosity

Answer 1

view-independent method of global illumination,

which is designed for diffuse-diffuse interaction.

The illumination of the scene is only calculated once and does not use any recursion

split the scene into patches
formulate the problem as a conservation of energy

Question 2

Form Factors

Answer 2

geometric relationship between patches i and j

The form factor between two patches is calculated :

energy leaving the original patch / energy leaving the patch in all directions

Question 3

Radiosity conditions:

Answer 3

The radiosity values are wavelength dependent,

hence we will need to
compute a radiosity value for R, G and B (all 3 colour channels).

Each patch will require a separate set of parameters for R,G and B.

The three radiosity values are the values that the rendered pixels will
receive

Question 4

Radiosity Term:

Answer 4

energy per unit area leaving a patch per unit time

(radiosity × area) should be the sum of the two types of energy:

emitted energy
reflected energy

Question 5

Hemicube

Answer 5

is divided into small “pixel” areas, where form factors are computed for each

Question 6

hemicube method:

Answer 6

1. Divides the hemicube into pixels
2. Calculates the nearest visible patch via projection
3. Sums up the pixels on the hemicube for which the patch is visible.

This is the form factor of the patch.

Question 7

issues with Radiosity

Answer 7

There can be alias errors
because we are splitting continuous surfaces into discrete units/patches

Like textures interpolation can be used