This is the documentation for Enlighten.

Probe sampling

Owned by Jun Yoshino
May 10, 2022
2 min read

The accuracy of the probe lighting for an actor depends on the sampling method used. 

Enlighten samples from probes on the rendering thread. To avoid reduced framerates, be aware of the cost.

Per-mesh sampling

This method allocates each mesh either one or multiple samples, depending on the size of the mesh.

With a single sample, the lighting varies depending only on the surface normal but not the position on the surface. A single sample is sufficient for small meshes, but may cause noticeable mismatching lighting between adjacent larger meshes.

The cost of per-mesh sampling increases with the number of meshes that are lit using probes. With this method, we recommend you limit the total number of meshes lit using probes. In particular, avoid many Foliage instances lit using probes.

Per-pixel sampling

This method makes a sample for each screen pixel to provide the most accurate lighting possible. This ensures that even very large meshes are always lit to match their surroundings.

The cost of per-pixel sampling increases with the number of probes updated. With this method there is no need to limit on the number of meshes lit using probes.

Per-pixel sampling doesn't work with regular Enlighten Probe Volumes. Use Enlighten Adaptive Probe Volumes instead.

Per-pixel sampling is experimental and has some limitations that make it unsuitable for some use cases and platforms.

Choose a sampling method

By default, only per-mesh sampling is available. To enable per-pixel sampling, change the Available Probe Sample Methods project setting (Edit > Project Settings > Plugins > Enlighten).

If you want to use a different sampling method for each probe-lit mesh, choose Both. Afterwards, you can specify which method to use for an actor using the actor's Probe Sample Method property.

Using both probe sampling methods in the same project adds cost on the rendering thread. To minimize the cost, choose either per-pixel or per-mesh sampling.

Choose the location of probe samples

When using per pixel sampling, by default the lighting is sampled at the surface of the mesh. This can sometimes result in a light leak when the mesh is large and intersects a wall that separates a bright area from a dark area. To work around this type of light leak, you can force the sample location to the center of the component's bounding box. To do this, set Probe Sample Location to Bounds Center.

When using per mesh sampling, by default, a single sample is used if the mesh's bounding sphere is smaller than 400 world units. If it's larger, multiple samples are used. To change this threshold, set the en.EnlightenLargeObjectThreshold variable. To force either a single or multiple samples for a given actor, use its Probe Sample Count property.