Indirect illumination examples

Example 1: Comparisons of different GI methods

Example 2: GI caustics

Example 3: Light bounces

Example 1: Comparisons of different GI methods

Here is a scene rendered with different GI algorithms in V-Ray. Combining the different GI engines allows great flexibility in balancing time versus quality of the final image.

Brute force GI, 4 bounces. The image is darker because only 4 light bounces are computed. Notice the grain and the long render time.
Irradiance map + brute force GI, 4 bounces. The image is darker because only 4 light bounces are computed. The grain is gone, although the GI is a little blurry (see the GI caustics below the glass sphere).
Light cache only. Very fast, but shadows are blurry (Store direct light for the light map is on).
Light cache and direct lighting (Store direct light is off).

Brute force GI + light cache, there is some grain in the GI but is a lot faster than brute force GI alone.
Irradiance map + light cache; probably the best quality/speed ratio.
Photon map only, notice the caustics from the glass sphere, as well as the dark corners.
Photon map and direct lighting

Photon map with precomputed irradiance only; splotchy, but faster than a raw photon map.
Irradiance map + photon map, notice the dark corners and incorrect shading on the letters.
Irradiance map + photon map with retracing of corners; corners are better although still a little dark
Irradiance map + photon map with precomputed irradiance, with corner retracing

Irradiance map + light cache with GI caustics enabled (notice the slowdown because of the caustics)
Light cache in Progressive path tracing Mode with photon-mapped caustics. Render time is quite high.

Example 2: GI caustics

This example shows GI caustics generated by a self-illuminated object:

Example 3: Light bounces

This example shows the effect of the number of light bounces on an image:

Direct lighting only: GI is off

1 bounce: irradiance map, no secondary GI engine
2 bounces: irradiance map + brute force GI with 1 secondary bounce

4 bounces: irradiance map + brute force GI with 3 secondary bounces
8 bounces: irradiance map + brute force GI with 7 secondary bounces
Unlimited bounces (complete diffuse lighting solution): irradiance map + light cache

Brute force GI, 4 bounces. The image is darker because only 4 light bounces are computed. Notice the grain and the long render time.	Irradiance map + brute force GI, 4 bounces. The image is darker because only 4 light bounces are computed. The grain is gone, although the GI is a little blurry (see the GI caustics below the glass sphere).	Light cache only. Very fast, but shadows are blurry (Store direct light for the light map is on).	Light cache and direct lighting (Store direct light is off).
Brute force GI + light cache, there is some grain in the GI but is a lot faster than brute force GI alone.	Irradiance map + light cache; probably the best quality/speed ratio.	Photon map only, notice the caustics from the glass sphere, as well as the dark corners.	Photon map and direct lighting
Photon map with precomputed irradiance only; splotchy, but faster than a raw photon map.	Irradiance map + photon map, notice the dark corners and incorrect shading on the letters.	Irradiance map + photon map with retracing of corners; corners are better although still a little dark	Irradiance map + photon map with precomputed irradiance, with corner retracing
Irradiance map + light cache with GI caustics enabled (notice the slowdown because of the caustics)	Light cache in Progressive path tracing Mode with photon-mapped caustics. Render time is quite high.