ReSTIR emissive: room lighting pulses / swaps every few seconds with an emissive-textured light prim (blocks 1.5 Beta 4) #1138

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opened 2026-10-27 08:57:29 +00:00 by sky_line · 0 comments

sky_line commented

2026-10-27 08:57:29 +00:00

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ReSTIR emissive lights make room lighting pulse / swap every few seconds. Blocks 1.5.0 Beta 4 (seen on the candidate release/1.5 ef4853e8b5).

Owner, 2026-10-27, desktop RTX 5090, a room lit by a prim light that also has an emissive texture (so the ReSTIR emissive build converts it into emissive light samples):

On the 1.5 candidate: every few seconds the room gets brighter and the stochastic shadows "explode a bit, then recede back" (not lightning -- confirmed). Recording: owner's Screencast_20261027_043259.webm (~5.5 s in).
On dev (with async-lighting step 1 on top): which corner of the room is lit SWAPS every few seconds -- one corner lit while the other is dark, then they swap. Likely the same bug showing differently.
RenderVKReSTIREmissive 0 (live) STOPS it. RenderVKAsyncCompute 0 does not (not a cross-queue race).

Suspects: the seconds-scale cadence of the emissive build (emitter update / rotation / 'due' sets, its parity, the emissive grid and the pair caps from #1108, the walk-occupancy changes), the emissive emitter's power / PDF estimate (coarsest-mip texture sampling) changing between updates, and the interaction with the prim's own point light (double counting or one replacing the other).

ReSTIR emissive lights make room lighting pulse / swap every few seconds. **Blocks 1.5.0 Beta 4** (seen on the candidate release/1.5 `ef4853e8b5`). **Owner, 2026-10-27, desktop RTX 5090, a room lit by a prim light that also has an emissive texture** (so the ReSTIR emissive build converts it into emissive light samples): - On the 1.5 candidate: every few seconds the room gets brighter and the stochastic shadows "explode a bit, then recede back" (not lightning -- confirmed). Recording: owner's Screencast_20261027_043259.webm (~5.5 s in). - On dev (with async-lighting step 1 on top): which corner of the room is lit SWAPS every few seconds -- one corner lit while the other is dark, then they swap. Likely the same bug showing differently. - `RenderVKReSTIREmissive 0` (live) STOPS it. `RenderVKAsyncCompute 0` does not (not a cross-queue race). **Suspects:** the seconds-scale cadence of the emissive build (emitter update / rotation / 'due' sets, its parity, the emissive grid and the pair caps from #1108, the walk-occupancy changes), the emissive emitter's power / PDF estimate (coarsest-mip texture sampling) changing between updates, and the interaction with the prim's own point light (double counting or one replacing the other).

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