Diagnostics and validation

Symptom	Check	Action
Everything is too bright/dark	Exposure mode, EV100, compensation	Lock Manual exposure; establish light values; then restore bounded adaptation
Bright object at screen edge pumps exposure	HDR histogram / metering	Add center-weighted Exposure Metering Mask or narrow histogram selection
Interior is black with Lumen	Surface Cache/Card coverage, mesh scale/topology	Split overly complex meshes; verify distance fields and Lumen representation
Light leaks through thin walls	Lumen representation, wall thickness, shadow method	Increase physical thickness; inspect distance fields; choose appropriate tracing/shadow path
Reflections miss objects	Lumen reflection mode/scene representation	Inspect Lumen scene; consider hardware RT where target supports it
Soft shadow is wrong	Source size, not intensity	Tune Source Radius/Width/Height/Angle
Local light costs too much	Bounds, shadows, overlaps	Reduce attenuation, disable unnecessary shadows, profile MegaLights versus conventional path
MegaLights looks noisy/blurry	Too many important overlapping lights per pixel	Narrow bounds, merge small lights, reduce local complexity
MegaLights ghosts in motion	Denoiser under high stochastic complexity	Simplify overlapping lights; test shadow method and temporal behavior
Fog glows everywhere	Volumetric scattering and large light bounds	Lower scattering; narrow bounds; remove irrelevant fog contribution
Day/night color looks fake	Manual tint fights Sky Atmosphere	Return sun toward neutral and let atmospheric scattering drive color
Emissive surface does not light enough	Emissive is visible but GI contribution is insufficient/noisy	Add a matching controlled light; do not rely on tiny bright emissives alone
Shadow acne/peter-panning	Bias settings or geometry	Inspect geometry/normals; tune bias minimally; verify VSM/ray-traced path

Debug sequence

1. Disable stylistic post effects that obscure diagnosis.
2. Lock exposure.
3. Inspect unlit/material values where relevant.
4. Inspect HDR (Eye Adaptation).
5. Inspect Lumen Overview, Surface Cache, and reflection views.
6. Inspect shadow/VSM or ray-tracing debug views.
7. Inspect light bounds and overlapping influence.
8. Measure GPU timing on target hardware and intended scalability.
9. Re-enable post effects one category at a time.

Acceptance checks

• Focal subject reads at gameplay camera distance.
• Exposure transitions behave intentionally in both directions.
• Direct, indirect, reflection, emissive, and volumetric contributions are identifiable.
• No major light leaks, black Lumen surfaces, temporal ghosting, or unstable pumping.
• Scene remains legible at required scalability tiers.
• GPU cost meets the declared budget on target hardware.