FAQ

What does Spectral do?

Spectral bakes lighting into surface lightmaps and probe fields. Lightmaps store lighting on static geometry; probes provide lighting throughout a space for moving objects and supported fog and capsule-shadow integrations. The plugin also includes tools for lightmap UVs, reflections, shadows, ambient occlusion, and tonemapping.

Start with First bake for a complete setup.

Can I use it for mobile or VR?

Yes, for static lightmap and probe-surface lighting playback on supported configurations. Not every Spectral feature runs on mobile or VR: effects such as GTAO and probe-lit volumetric fog have additional renderer restrictions. For a mobile baked setup, set the Sky Light to Static before baking.

Check Platforms and systems for each feature before choosing your target setup.

Do players need a ray-tracing GPU?

No, not to play back the baked lightmaps and probe lighting. Hardware ray tracing is required to create the bake, using the supported Windows DirectX 12 setup. Runtime requirements depend on the features you enable and the target renderer.

Can moving characters use the baked lighting?

Yes. Place and bake probe fields around the areas they move through. The character samples the stored lighting as it moves. Supported renderers can also use that field to drive indirect capsule shadows, provided the character has a working capsule-shadow setup.

Follow Probe lighting for coverage, interpolation, and testing.

Can baked lighting move with an elevator or another Blueprint?

Yes. The prefab system can capture surface lightmaps and embedded probe fields for a reusable Blueprint, such as an elevator cabin. The stored lighting moves with the prefab; it does not recalculate itself to match each new environment.

When do I need to bake again?

Rebake after changing lights, static geometry, lightmap UVs, probe layout, or bake-quality settings that should appear in the result. Changing GTAO, tonemapping, probe interpolation, fog lighting balance, or Fog Filtering does not require a new lighting bake.

Update Bake Reflections after changes that should appear in reflection captures. For a prefab, rebake its source and capture again when its stored lighting needs updating. Save the affected maps and assets afterward.

Can I bake while using Vulkan?

No. Restart the Windows editor with -dx12, bake using the required authoring settings, and save the lighting. Then restart on Vulkan to test playback. See baking requirements.

How do I install Spectral?

Install it to your Unreal Engine version through the Fab Library in Epic Games Launcher, then enable it under Edit > Plugins. Leave the separate GPU Lightmass plugin disabled because Spectral provides its own baker. Follow Installation for project settings and shader-hook setup.

Will installing Spectral affect my other projects?

Enabling Spectral's shader hooks changes files in the engine installation. Other projects using that engine installation share those shader files. Use a separate engine installation if you need isolation, and disable the hooks before uninstalling Spectral. See Shader hooks.

Where can I get help?

Check Troubleshooting, or contact me directly. Include your Unreal and Spectral versions, target platform, renderer, and the steps that reproduce the issue. Add the error report, crash report, or a screenshot when relevant.