Last reviewed 31 Jul 2026

Applies to

Unity 2022.3 Progressive GPU Lightmapper VRChat world projects

Difficulty Intermediate

Use the Progressive GPU Lightmapper in Unity 2022.3

Unity’s Progressive GPU Lightmapper uses a compatible GPU and its dedicated VRAM to generate baked lightmaps and Light Probes. Unity 2022.3 labels this backend as a preview feature, so keep Progressive CPU available when a scene or workstation cannot complete the GPU bake reliably.

Unity 2022.3 Requirements

The Progressive GPU Lightmapper requires:

Requirement	Unity 2022.3 minimum
GPU	OpenCL 1.2 support
Dedicated GPU memory	At least 4 GB of VRAM
CPU	SSE4.1 instruction support

CPU OpenCL devices are not supported. A machine that does not meet these requirements should use Progressive CPU.

Progressive CPU and Progressive GPU

Backend	Processing resources	Important behavior
Progressive CPU	CPU and system RAM	Unity’s default Progressive Lightmapper backend
Progressive GPU	GPU and dedicated VRAM	Usually faster unless lightmapper tiling is active

Unity notes that Progressive GPU can require up to four times more indirect-light samples to reach the same quality as Progressive CPU because the CPU backend uses branched path tracing.

Both backends use the Progressive Lightmapper and require suitable non-overlapping lightmap UVs with enough padding between charts.

1. Create or Assign Lighting Settings

1. Open Window → Rendering → Lighting.
2. Select the Scene tab.
3. Assign an existing Lighting Settings asset or select New Lighting Settings.
4. Expand Lightmapping Settings.

The Lightmapper selection belongs to the Lighting Settings asset assigned to the active scene.

2. Select Progressive GPU

1. Find Lightmapper under Lightmapping Settings.
2. Change Progressive CPU to Progressive GPU.
3. Keep Baked Global Illumination enabled.
4. Disable Auto Generate when each test bake should start manually.
5. Select Generate Lighting.

If Progressive GPU is unavailable, do not force the project onto an undocumented backend. Recheck the Unity 2022.3 requirements and use Progressive CPU when the workstation does not meet them.

3. Select the Baking GPU

When the computer contains at least two GPUs:

1. Open the Lighting window.
2. Find Workflow Settings.
3. Use GPU Baking Device to select the GPU Unity should use for lighting.

The GPU Baking Device control appears only while the Progressive GPU backend is selected. A separate baking GPU can preserve more VRAM when the primary GPU is also rendering the Scene view.

4. Run a Controlled Test Bake

Before changing final-quality settings:

1. Save the scene.
2. Disable Auto Generate.
3. Use the scene’s current lightmap resolution and sampling settings for a baseline.
4. Select Generate Lighting.
5. Record whether the bake completes, how long it takes, and whether Unity reports fallback or memory problems.
6. Inspect the Baked Lightmaps tab and the Scene view result.

Change one bake setting at a time after establishing the baseline. Otherwise, a faster or slower result cannot be attributed to the backend alone.

5. Recognize Lightmapper Tiling

Lightmapper tiling activates when Unity cannot access enough GPU memory to bake an entire lightmap. Instead of immediately falling back to Progressive CPU, Unity:

1. allocates temporary memory on the CPU
2. divides the lighting work into tiles sized for the available GPU memory
3. bakes those tiles through the GPU

While tiling is active:

• the bake is slower than the same scene without tiling
• progressive updates stop in the Scene view and bake process
• the Progressive Updates setting does not visibly turn off

Tiling cannot be disabled directly. Reduce its likelihood by freeing VRAM or reducing the bake’s memory requirements.

6. Reduce GPU Memory Use

Unity documents several ways to reduce VRAM pressure:

Change	Where
Close GPU-accelerated image, video, or 3D applications	Outside Unity
Lower Lightmap Resolution	Lighting window, Lightmapping Settings
Disable baked Ambient Occlusion	Lighting window, Lightmapping Settings
Reduce anti-aliasing samples	Project Settings → Quality
Select a lower-resolution Lightmap Parameters asset	Lighting window, Lightmapping Settings
Use OpenImageDenoise	Set Filtering to Advanced and select the CPU-based denoiser
Remove small props from lightmaps	Disable Contribute GI and light them with Light Probes
Use separate rendering and baking GPUs	Workflow Settings → GPU Baking Device

OpenImageDenoise runs on the CPU and uses system RAM. Optix and RadeonPro denoisers use GPU resources; Unity notes that RadeonPro uses substantially more GPU memory.

7. Tune Samples for the GPU Backend

Reducing samples can shorten a test bake, but it can also leave noise in the lightmaps. For final output:

1. inspect direct and indirect lighting separately
2. increase the sample type responsible for visible noise
3. use a compatible denoiser
4. rebake and compare the same camera positions

Progressive GPU may require up to four times more indirect samples than Progressive CPU for equivalent quality. Do not assume the same indirect-sample value produces the same result on both backends.

8. Inspect the Finished Data

After a successful bake:

1. Open the Baked Lightmaps tab.
2. Check the number and resolution of generated lightmaps.
3. Inspect seams, chart padding, shadow noise, leaks, and texel density.
4. Verify Light Probe results on movable objects.
5. Enter Play mode and inspect occupied areas.
6. Test the intended VRChat PC and Android builds separately.

GPU lightmapping does not correct overlapping lightmap UVs, insufficient chart padding, excessive lightmap resolution, or unnecessary Contribute GI renderers.

Video Example

This existing tutorial shows the broader baked-lighting workflow that the GPU backend accelerates.

Help! Progressive GPU is not available.

Confirm the system has an OpenCL 1.2-capable GPU with at least 4 GB of dedicated VRAM and a CPU with SSE4.1 support. CPU OpenCL devices do not qualify. Use Progressive CPU when the requirements are not met.

Help! Unity falls back to Progressive CPU.

Free GPU memory by closing other accelerated applications, reduce lightmap resolution or anti-aliasing samples, move denoising to OpenImageDenoise, and remove small props from Contribute GI before running the bake again.

Help! Progressive updates stopped and the bake became slow.

Lightmapper tiling may be active because the complete lightmap does not fit in available VRAM. The Progressive Updates control does not visibly disable when this happens. Reduce VRAM use and repeat the bake.

Help! The GPU bake runs out of memory.

Lower Lightmap Resolution, reduce anti-aliasing samples, select lower-resolution Lightmap Parameters, use a CPU denoiser, free VRAM, or select another GPU Baking Device. Progressive CPU remains the fallback backend.

Help! The GPU bake is noisier than the CPU bake.

Increase indirect samples and use a compatible denoiser. Unity documents that Progressive GPU can need up to four times more indirect samples to match Progressive CPU quality.

Help! The Android world is still expensive after switching to GPU.

The backend only changes Editor baking. Reduce final lightmap resolution, remove unnecessary realtime lights and shadows, use Light Probes, and retest the Android build using VRChat’s platform guidance.

Official References

• Unity 2022.3 Manual: Progressive Lightmapper
• Unity 2022.3 Manual: Progressive GPU Lightmapper
• Unity 2022.3 Manual: Lighting window
• Unity 2022.3 Manual: Lightmapping
• VRChat: Android Content Optimization

Continue Learning

• Unity Lighting for VRChat Worlds
• Introduction to Unity3D Lighting
• Set Up a Skybox and Environment Lighting in Unity
• Install and Bake with Bakery GPU Lightmapper
• World Optimization Checklist
• Unity Performance Basics for VRChat Worlds