Example 1: Comparisons of different GI methods

Example 2: GI caustics

Example 3: Light bounces

Example 4: Ambient occlusion

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

Example 4: Ambient occlusion

Note: the scene in this example is from Evermotion (http://www.evermotion.org/)

 

This example demonstrates the effect of the global ambient occlusion options.

 

The first image to the right is rendered with the Light cache for both primary and secondary bounces, Fixed Filter type for the light cache, and Store direct light off. The second image in the center is rendered with the same light cache settings, but with global ambient occlusion enabled. The third image to the right is rendered without ambient occlusion, with Brute force GI engine for primary bounces, and the Light cache as a secondary engine with Nearest Filter type. The render times include the time for calculating the light cache. Note how ambient occlusion can produce a feeling of a more detailed image, even though the result is not entirely correct.

Ambient occlusion is off - lighting is good, but there is a lack of detail Ambient occlusion is on - details are much more defined Brute force GI, no ambient occlusion - details are fine, but render times is longer.