Automatic probe placement

Any surface can take indirect lighting from nearby Enlighten probes. For accurate indirect lighting, probes must be placed nearby with a sufficient output resolution. For an effective Enlighten workflow, the artist shouldn't have to manually position each probe.

A naive solution would be to place probes at a fixed resolution across a box that is the size of the entire world. This produces an extremely inefficient distribution of probes, especially when the resolution is high. For a small world, the large number of probes generated may be tolerable, but would quickly become a problem as the size of the world increases. For a larger world, a more efficient distribution of probes is required.

The images below show a large world with a fixed resolution of probes. 

Control automatic placement

In a typical game, objects that move at runtime are constrained to a limited playing area. Some parts of the playing area will not be seen up close by the player, and can use a reduced indirect lighting resolution. To minimize the number of probes, reduce the resolution in ares where objects will not move, or where objects are seen only at long distance. To control this, the artist defines a number of regions and a desired output resolution for each region.

Static objects typically cover a much smaller region of the playing area than objects that move: we can afford to increase the resolution of probes around these objects. Static objects take indirect lighting from a fixed region around the mesh which can be determined automatically. Only artist input required: the desired output resolution for the object.

In many cases, these regions and resolutions can be automatically determined by your editor tools. For example, your editor may automatically define a region with a sensible resolution to cover the areas of a terrain where characters can walk.

Simplified example

The example below shows a terrain with two trees, a volume placed to cover the areas of terrain where characters can walk, and the resolution chosen for the volume.

The example below shows how you can automatically determine where probes are required for static objects like trees, but let the artist control the resolution for each object. The third image shows the combination of regions of different resolutions.

The example below shows a building placed on the terrain, a volume placed to cover the interior of the building, and the higher resolution chosen for the volume.

The illustrations below show the combination of regions of different resolutions, and the initial placement of probes.

Real world example

The images below show a large world and the way Enlighten's automatic probe placement determines the required resolution.