11 KiB
Fix issues with Adaptive Probe Volumes
Adjust settings or use Volume overrides to fix artefacts from Adaptive Probe Volumes.
How Light Probe validity works
Light Probes inside geometry are called invalid probes. The High Definition Render Pipeline (HDRP) marks a Light Probe as invalid when the probe fires sampling rays to capture surrounding light data, but the rays hit the unlit backfaces inside geometry.
HDRP uses the following techniques to minimise incorrect lighting data from Light Probes:
- Virtual Offset tries to make invalid Light Probes valid, by moving their capture points so they're outside any colliders.
- Dilation detects Light Probes that remain invalid after Virtual Offset, and gives them data from valid Light Probes nearby.
- Rendering Layers prevent objects from sampling probes that are on another Layer Mask, reducing light leaking in certain scenarios.
You can check which Light Probes are invalid using the Rendering Debugger.
In the Scene on the left, Virtual Offset isn't active and dark bands are visible. In the Scene on the right, Virtual Offset is active.
In the Scene on the left, Dilation isn't active and some areas are too dark. In the Scene on the right, Dilation is active.
Fix dark blotches or streaks
Adjust Virtual Offset
You can configure Virtual Offset Settings in the Adaptive Probe Volumes panel in the Lighting window. This changes how HDRP calculates the validity of Light Probes.
You can adjust the following:
- The length of the sampling ray Unity uses to find a valid capture point.
- How far Unity moves a Light Probe's capture position to avoid geometry.
- How far Unity moves the start point of rays.
- How many times a probe's sampling ray hits colliders before Unity considers the probe invalid.
You can also disable Virtual Offset for a Baking Set. Virtual Offset only affects baking time, so disabling Virtual Offset doesn't affect runtime performance.
Adjust Dilation
You can configure Probe Dilation Settings in the Adaptive Probe Volumes panel in the Lighting window). This changes how HDRP calculates the validity of Light Probes, and how invalid Light Probes use lighting data from nearby valid Light Probes.
You can adjust the following:
- The percentage of backfaces a Light Probe can sample before HDRP considers that probe invalid.
- How far away from the invalid probe Unity searches for valid probes to contribute lighting data.
- How many iterations of Dilation HDRP does during the bake.
- How to weight the data from valid probes based on their spatial relationship with the invalid probe.
How you adjust Light Probe density affects the final results, because HDRP uses the settings as a multiplier to calculate the distance between probes.
You can also disable Dilation for a Baking Set. Dilation only affects baking time, so disabling Dilation doesn't affect runtime performance.
Fix light leaks
Light leaks are areas that are too light or dark, often in the corners of a wall or ceiling.
A light leak.
Light leaks often occur when geometry receives light from a Light Probe that isn't visible to the geometry, for example because the Light Probe is on the other side of a wall. Adaptive Probe Volumes use regular grids of Light Probes, so Light Probes might not follow walls or be at the boundary between different lighting areas.
To fix light leaks, you can do the following:
- Create thicker walls.
- Add an Adaptive Probe Volumes Options override to your scene.
- Enable Rendering Layers.
- Adjust Baking Set properties.
- Use a Probe Adjustment Volume.
Create thicker walls
Adjust walls so their width is closer to the distance between probes in the local brick
Add an Adaptive Probe Volumes Options override to your scene
You can add a Volume, then add an Adaptive Probe Volumes Options override to the Volume. This adjusts the position that GameObjects use to sample the Light Probes.
- Add a Volume to your scene and make sure its area overlaps the camera position.
- Select Add Override, then select Lighting > Adaptive Probe Volumes Options.
- Enable Normal Bias, then adjust the value to move the position that GameObject pixels use to sample the Light Probes, along the pixel's surface normal.
- Enable View Bias, then adjust the value to move the position that GameObject pixels use to sample the Light Probes, towards the camera.
- Disable and enable Leak Reduction Mode to check if it improves light leaks.
Volumes only affect the scene if the camera is near or inside the volume. Refer to Understand volumes for more information.
Refer to Probe Volumes Options Override reference for more information on Probe Volumes Options settings.
Use Rendering Layer Masks
You can configure the Rendering Layer Masks in the Adaptive Probe Volumes panel in the Lighting window. This allow APV to assign a Rendering Layer Mask to each Light Probe.
For performance reasons, Adaptive Probe Volumes only supports up to 4 Rendering Layers Masks. You can use the list to create a new mask and use the dropdown to assign it any Rendering Layer. When lighting is generated, Unity will try to automatically assign a mask to each probe by looking at the Rendering Layer Masks of objects surrounding the probe. Additionally, you can use a Probe Adjustment Volume to override the Rendering Layer Mask assigned to Light Probes.
At runtime, renderers will only sample lighting data from probes that have a matching Rendering Layer Mask. If the object doesn't match any of the Masks defined in the Lighting window, it will sample lighting from all the valid surrounding probes. Note that this feature requires Light Layers to be enabled in the HDRP Asset.
For example, in order to fix light leaking issues, you can create an Interior and an Exterior Rendering Layer Mask to ensure interior objects will never sample lighting data from exterior probes and fix light leaking through the walls. A renderer can have several Rendering Layers enabled in it's Rendering Layer Masks. This is useful when dealing with dynamic objects that may want to sample lighting from both the exterior and interior probes.
In HDRP, you can use the Rendering Debugger to visualize which layers are assigned to an object:
- Go to the Material tab
- Set the Material field to Common > Rendering Layers
You can also visualize which layers are assigned to a probe:
- Go to the Probe Volumes tab
- Enable Display Probes
- Set the Probe Shading Mode field to Rendering Layer Masks
- Use the toggles in the Scene View Overlay to hide Probes matching a Rendering Layer Mask
Adjust Baking Set properties
If adding a Volume doesn't work, use the Adaptive Probe Volumes panel in the Lighting window to adjust Virtual Offset and Dilation settings.
- In Probe Dilation Settings, reduce Search Radius. This can help in situations where invalid Light Probes are receiving lighting data from more distant Light Probes. However, a lower Search Radius might cause light leaks.
- In Virtual Offset Settings, reduce Search Distance Multiplier and Ray Origin Bias.
- If there are light leaks in multiple locations, adjust Min Probe Spacing and Max Probe Spacing to increase the density of Light Probes.
- Select Generate Lighting to rebake the scene using the new settings.
Note: Don't use very low values for the settings, or Dilation and Virtual Offset might not work.
Add a Probe Adjustment Volume component
Use a Probe Adjustment Volume component to make Light Probes invalid in a small area. This triggers Dilation during baking, and improves the results of Leak Reduction Mode at runtime.
- In the GameObject menu, select Light > Probe Adjustment Volume.
- Set the Size so the Probe Adjustment Volume area overlaps the Light Probes causing light leaks.
- Set Probe Volume Overrides > Mode to Invalidate Probes, to invalidate the Light Probes in the Volume.
- If you have a Volume with an Adaptive Probe Volumes Options override, enable Leak Reduction Mode.
- In the Lighting Window, select Generate Lighting to rebake the scene using the new settings.
Clicking the 'Update Probes' button inside the Probe Adjustment Volume editor will regenerate the lighting data for probes covered by the volume. This is useful when iterating on a region of the world as it avoids baking the whole scene to see the result. Note that this button will only run the lighting and validity computations, so changing the space between probes, or toggling Virtual Offset or Sky Occlusion will not have any effect until doing a full rebake of the Baking Set.
Using a Probe Adjustment Volume component solves most light leak issues, but often not all.
Probe Adjustment Volumes are sorted by size, so smaller volumes will have priority when multiple Adjustment Volumes are affecting the same probe. If you use many Probe Adjustment Volumes in a scene, your bake will be slower, and your scene might be harder to understand and maintain.
Refer to Probe Adjustment Volume component reference for more information.
Fix seams
Seams are artefacts that appear when one lighting condition transitions immediately into another. Seams are caused when two adjacent bricks have different Light Probe densities. Refer to bricks for more information.
Two seams.
URP fixes seams automatically.
If a seam issue persists, add noise as follows:
- Add a Volume to your scene and make sure its area overlaps the position of the camera.
- Select Add Override, then select Lighting > Adaptive Probe Volumes Options.
- Enable Sampling Noise, then try adjusting the value to add noise and make the transition more diffuse. Noise can help break up noticeable edges in indirect lighting at brick boundaries.