Progressive GPU Lightmapper (Preview)

Note: This is a preview feature and is subject to change. If you have Scenes that use this feature, you might need to update them in a future release. Do not rely on this feature for full-scale production until it is officially released.

The GPU Lightmapper gives you an interactive workflow when you’re setting up and tweaking the lighting in your Scene. Because this lightmapper uses the GPU in your computer to generate baked lightmaps and Light probes, it’s a faster alternative to the CPU Progressive Lightmapper.

Settings

To use the Progressive GPU (Preview) Lightmapper, go to Window > Rendering > Lighting Settings, navigate to Lightmapping Settings, and set Lightmapper to Progressive GPU (Preview). See Lightmapping Settings for more information about this window.

Setting		Description
Lightmapper		Use this to specify which internal lighting calculation software to use to calculate lightmaps in the Scene. The options are: Progressive CPU Progressive GPU Enlighten (deprecated) The default value is Progressive CPU.
Prioritize View		Enable this to make the Progressive Lightmapper apply changes to the texels that are currently visible in the Scene View, then apply changes to the out-of-view texels.
Multiple Importance Sampling		Enable this to use multiple importance sampling for sampling the environment. This generally leads to faster convergence when generating lightmaps, but can lead to noisier results in certain low frequency environments. This is disabled by default.
Direct Samples		The number of samples (paths) shot from each texel. This setting controls the number of samples Progressive Lightmapper uses for direct lighting calculations. Increasing this value can improve the quality of lightmaps, but increases the baking time.
Indirect Samples		The number of samples (paths) shot from each texel. This setting controls the number of samples Progressive Lightmapper uses for indirect lighting calculations. For some Scenes, especially outdoor Scenes, 100 samples should be enough. For indoor Scenes with emissive geometry, increase the value until you see the result you want.
Environment Samples		Define the number of samples the lightmapper uses for environment lighting calculations. Higher values can improve the quality of the lightmaps, but increase the time required for baking to complete. This is set to 500 by default.
Light Probe Sample Multiplier		Controls how many samples are used for Light Probes as a multiplier of the sample values above. Higher values improve the quality of Light Probes, but they will take longer to bake. To enable this feature, go to Project Settings > Editor and disable Use legacy Light Probe sample counts. The default value is 4.
Bounces		Use this value to specify the number of indirect bounces to do when tracing paths. For most Scenes, two bounces is enough. For some indoor Scenes, more bounces might be necessary.
Filtering		Configure the way the Progressive Lightmapper applies post-processing to lightmaps to limit noise. For lightmap post-processing, the lightmap is split into Direct, Indirect and Ambient Occlusion targets that Unity applies post-processing to individually, before it composites them together into a single lightmap. - Direct: Any light that arrives directly from a Light to a sensor (usually the Camera). - Indirect: Any light that arrives indirectly from a Light to a sensor. This most commonly applies to light that reflects off other GameObjects. - Ambient Occlusion: Any ambient light that the lighting system calculates. See Ambient Occlusion for more information.
	None	Select this to use no filter or denoising for the lightmap.
	Auto	Select this to use a platform-dependent preset for post-processing the lightmap. If your development machine fulfils the requirements to run OptiX (the NVIDIA OptiX AI-Accelerated Denoiser), the Progressive Lightmapper uses the denoiser with a Gaussian filter that has a 1-texel radius for all targets. If your development machine cannot run OptiX, the Progressive Lightmapper uses a Gaussian filter that has a 1-texel radius for Direct, 5-texel radius for Indirect, and 2-texel radius for Ambient Occlusion.
	Advanced	Select Advanced to manually configure options for each type of lightmap target. The targets types are Direct, Indirect and Ambient Occlusion. For more information, see Advanced Filtering settings, below.
Indirect Resolution		Use this to specify the number of samples the lightmapper uses for indirect lighting calculations. Higher values can improve the quality of the lightmaps, but increase the time it takes to bake them.
Lightmap Resolution		Use this to specify the number of texels per unit to use for lightmaps. Increasing this value improves lightmap quality, but also increases bake times. Note that doubling this value causes the number of texels to quadruple (because the value refers to both the height and width of the lightmap). See the Occupied texels count in the statistics area at the bottom of the Lighting window.
Lightmap Padding		Use this to specify the separation (in texel units) between separate shapes in the baked lightmap. The default value is 2.
Lightmap Size		The size (in pixels) of the full lightmap texture, which incorporates separate regions for the individual GameObject textures. The default value is 1024.
Compress Lightmaps		A compressed lightmap requires less storage space, but the compression process can introduce unwanted visual effects into the texture. Tick this checkbox to compress lightmaps, or untick it to keep them uncompressed. The checkbox is ticked by default.
Ambient Occlusion		Tick this checkbox to open a group of settings which allow you to control the relative brightness of surfaces in ambient occlusion. Higher values indicate a greater contrast between the occluded and fully lit areas. This only applies to the indirect lighting calculated by the GI system. This setting is enabled by default.
	Max Distance	Set a value to control how far the lighting system casts rays in order to determine whether or not to apply occlusion to an object. A larger value produces longer rays and contributes more shadows to the lightmap, while a smaller value produces shorter rays that contribute shadows only when objects are very close to one another. A value of 0 casts an infinitely long ray that has no maximum distance. The default value is 1.
	Indirect Contribution	Use the slider to scale the brightness of indirect light as seen in the final lightmap (that is, ambient light, or light bounced and emitted from objects) from a value between 0 and 10. The default value is 1. Values less than 1 reduce the intensity, while values greater than 1 increase it.
	Direct Contribution	Use the slider to scale the brightness of direct light from a value between 0 and 10. The default value is 0. The higher this value is, the greater the contrast applied to the direct lighting.
Directional Mode		You can set the lightmap up to store information about the dominant incoming light at each point on the objects’ surfaces. See documentation on Directional Lightmapping for further details. The default mode is Directional.
	Directional	In Directional mode, Unity generates a second lightmap to store the dominant direction of incoming light. This allows diffuse normal mapped materials to work with the GI. Directional mode requires about twice as much storage space for the additional lightmap data. Directional lightmaps cannot be decoded on SM2.0 hardware or when using GLES2.0. They fall back to Non-Directional lightmaps.
	Non-directional	Non-directional mode disables Unity’s ability to generate a second lightmap to store the dominant direction of incoming light.
Indirect Intensity		Use this slider to control the brightness of indirect light stored in realtime and baked lightmaps, from a value between 0 and 5. A value above 1 increases the intensity of indirect light while a value of less that 1 reduces indirect light intensity. The default value is 1.
Albedo Boost		Use this slider to control the amount of light Unity bounces between surfaces, from a value between 1 and 10. To do this, Unity intensifies the albedo of materials in the Scene. Increasing this draws the albedo value towards white for indirect light computation. The default value of 1 is physically accurate.
Lightmap Parameters		Unity uses a set of general parameters for the lightmapping in addition to properties of the Lighting window. A few defaults are available from the menu for this property but you can also create your own lightmap parameter file using the Create New option. See the Lightmap Parameters page for further details. The default value is Default-Medium.

Advanced Filtering settings

Setting		Description
Advanced		Set Filtering to Advanced to manually configure options for each type of lightmap target. The target types are: - Direct: Any light that arrives directly from a Light to a sensor (usually the Camera). - Indirect: Any light that arrives indirectly from a Light to a sensor. This most commonly applies to light that reflects off other GameObjects. - Ambient Occlusion: Any ambient light that the lighting system calculates. See Ambient Occlusion for more information.
	Denoiser	Select a denoiser to use for the lightmap target. The options are: Optix: The NVIDIA Optix denoiser is an AI accelerated denoiser that reduces noise in baked lightmaps. It requires an NVIDIA GPU with 4GB+ VRAM and driver version 390+, and is only supported on the Windows platform. RadeonPro: The RadeonPro denoiser is an AI accelerated denoiser that reduces noise in baked lightmaps. It requires an OpenCL capable GPU with 4GB+ VRAM. - OpenImageDenoise: The Intel Open Image denoiser is an AI accelerated denoiser that reduces noise in baked lightmaps. - None: Do not use a denoiser.
	Filter	Select a filter to use for the lightmap target: - Gaussian: Select this to use a Gaussian filter for the lightmap target. The Gaussian filter applies a bilateral Gaussian filter on the lightmap. This blurs the lightmap and reduces the visible noise. - A-Trous: Select this to use an A-Trous filter for the lightmap target. The A-Trous filter minimizes the amount of blur while it removes visible noise in the lightmap. - None: Select this to disable all filtering for the lightmap target.
	Radius	This option is only available when Filter is set to Gaussian. Use the Radius value to set the radius of the Gaussian filter kernel in texels. A higher Radius increases the blur strength and reduces the perceptible noise, but might cause detail to be lost in the lighting.
	Sigma	This option is only available when Filter is set to A-Trous. Use the Sigma value to adjust how much to preserve detail or blur the lighting. A higher Sigma increases the blur strength and reduces the perceptible noise, but might cause detail to be lost in the lighting.

Hardware and software requirements

To use the Progressive GPU Lightmapper, your computer must have:

• At least one GPU with OpenCL 1.2 support
• At least 2GB of dedicated GPU memory
• A CPU that supports SSE4.1 instructions

If your computer has more than one GPU, Unity selects the same GPU that the Editor uses. You can also choose one GPU for rendering and a different GPU for light baking. For information on how to change this, see the Configure which GPU to use section of this page.

Note: If the baking process uses more than the available GPU memory, the process might fall back to the CPU Lightmapper. Some graphics drivers with virtual memory support swap to CPU memory instead, which makes the baking process slower.

Configure which GPU to use

You can select one GPU for rendering the Scene and another GPU for baking lighting. If the automatic GPU assignment doesn’t fit your needs, you can specify which graphics card to use for baking.

To see which GPU Unity currently uses for baking, in the Editor:

• In your Project, open the Lighting window (menu: Window > Rendering > Lighting Settings). Next to Bake Performance, you can see the GPU.

To see the available GPUs in your machine:

1. Select the Progressive GPU (Preview) lightmapper in the Lighting Settings window.
2. Generate the lighting in your Scene.
3. Open File Explorer, and navigate to the following path: C:\Users\USER\AppData\Local\Unity\Editor. Open the file called Editor.log.
4. In the file, search for the line Listing OpenCL platforms. This should jump to the part of the log with information about OpenCL devices. Here, you can see your available GPUs along with their corresponding platform and device indexes.

To select a specific GPU for baking, enter this command at the command line (replace platform and device index with the relevant numbers):

Unity.exe "-OpenCL-PlatformAndDeviceIndices" <platform> <device index>

Your choice of assignment should depend on your needs while you’re working on the Scene. If you assign the strongest GPU to either activity, this can incur a performance impact on the other activity. If you encounter issues, try re-assigning GPUs.

Progressive GPU limitations

The Progressive GPU Lightmapper does not support:

• Baked LOD
• A-Trous filtering (it only uses Gaussian filtering)
• The custom bake API (experimental)