What you're seeing
Skylight or outdoor indirect illumination appears inside a sealed cave, room, or other large enclosure.
Likely causes
- Lumen stops a trace before it reaches the required occluder.
- A wall is too thin for the software ray-tracing distance field to represent reliably.
- A large monolithic mesh has a poor distance-field representation.
- A mesh was imported small and scaled up without enough distance-field resolution.
Check in this order
- 01Use Lumen Overview to confirm that Lumen introduces the leak.
- 02Inspect Mesh Distance Fields and confirm the enclosure is closed and represented at the placed scale.
- 03For software tracing, separate large room geometry and keep important walls at least 10 cm thick.
- 04Raise Lumen Scene View Distance and Max Trace Distance only enough to reach the missing occluder.
Views and commands
Lumen Overview
View Mode > Lumen > OverviewCompares the lit scene with Lumen scene representations.
Mesh Distance Fields
Show > Visualize > Mesh Distance FieldsShows the signed distance field generated for each static mesh.
Post Process setting
Lumen Global Illumination > Lumen Scene View DistanceExtends the distance over which Lumen Scene is maintained.
Post Process setting
Lumen Global Illumination > Max Trace DistanceExtends traces so they can reach more distant occluders.