In most configurations, the Progressive GPU LightmapperA tool in Unity that bakes lightmaps according to the arrangement of lights and geometry in your scene. More info
See in Glossary performs much faster than the Progressive CPU Lightmapper. The performance depends on the selected Baking Profile.
However, the specifications of the GPU you use to bake and the amount of VRAM dedicated to that GPU both influence your experience of the lightmapper’s performance.
Other applications competing for GPU resources also have an impact on baking performance. Depending on your hardware vendor, reductions in the amount of VRAM available to Unity can slow down the bake process or cause it to fail.
In order to achieve results of the same quality as the Progressive CPU Lightmapper, the Progressive GPU Lightmapper needs up to four times more indirect light samples. The Progressive CPU Lightmapper uses an approach called branched path tracing, which launches more light rays at each bounce. The branched path tracing approach is not suitable for GPUs.
Unity provides a spreadsheet to help you determine how much memory the Progressive GPU Lightmapper needs to bake your sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary. For more information see the Progressive GPU Lightmapper Memory Spreadsheet .
The Progressive GPU Lightmapper includes a feature called lightmapper tiling. Lightmapper tiling prevents the Progressive GPU Lightmapper from using all available GPU memory. Instead, Unity allocates some temporary memory on the CPU, then bakes your lighting in tiles that are sized to match the amount of GPU memory available. Unity configures the tiling based on the selected Baking Profile. The Progressive CPU Lightmapper does not include a tiling feature.
When the tiling feature is active, and when the lightmapA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
See in Glossary atlas resolution is 512px or bigger, the baking process is likely to be slower than baking the same scene without tiling.
On macOS it is more difficult to determine how much memory is available. As a result, fallback to CPU is more likely on this platform and it is a best practice to follow instructions for optimizing your bake speed.
There are several ways you can reduce bake times and avoid situations where bakes exceed the VRAM available to the GPU designated for baking.
Close other GPU-accelerated applications. GPU-accelerated 2D image editing and 3D modelling software uses VRAM. Turn off accelerated graphics functionality or quit these applications.
Use Light Probes for smaller GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary.
GameObjects such as debris or small props use up space in lightmaps but might not contribute significantly to the look of a scene. To optimize bake speed, disable Contribute Global Illumination for these GameObjects’ Mesh Renderers and light them with Light ProbesLight probes store information about how light passes through space in your scene. A collection of light probes arranged within a given space can improve lighting on moving objects and static LOD scenery within that space. More info
See in Glossary instead.
Designate separate GPUs for rendering and baking. If your computer has more than one GPU, you can designate one for rendering and one for baking. See Configure GPU selection below.
Use a lower number of Anti-aliasing samples. The default value for this setting in the Lightmap Parameters Asset is 8. When you increase it, Unity uses more VRAM. When you are using a lightmap size of 4096 or above, this can quickly exceed the memory of many consumer GPUs.
Use fewer samples (Direct Samples, Indirect Samples, Environment Samples) and use the Denoiser to clean up the remaining noise in the lightmap.
Reduce your lightmap resolution.
If you have at least two GPUs, you can specify one GPU for rendering the Scene and another for baking lighting. This might be desirable in cases where there is insufficient VRAM available for the default GPU to both render your scene and bake it using the Progressive GPU Lightmapper.
To change which GPU Unity uses for baking:
Did you find this page useful? Please give it a rating:
Thanks for rating this page!
What kind of problem would you like to report?
Thanks for letting us know! This page has been marked for review based on your feedback.
If you have time, you can provide more information to help us fix the problem faster.
Provide more information
You've told us this page needs code samples. If you'd like to help us further, you could provide a code sample, or tell us about what kind of code sample you'd like to see:
You've told us there are code samples on this page which don't work. If you know how to fix it, or have something better we could use instead, please let us know:
You've told us there is information missing from this page. Please tell us more about what's missing:
You've told us there is incorrect information on this page. If you know what we should change to make it correct, please tell us:
You've told us this page has unclear or confusing information. Please tell us more about what you found unclear or confusing, or let us know how we could make it clearer:
You've told us there is a spelling or grammar error on this page. Please tell us what's wrong:
You've told us this page has a problem. Please tell us more about what's wrong:
Thank you for helping to make the Unity documentation better!
Your feedback has been submitted as a ticket for our documentation team to review.
We are not able to reply to every ticket submitted.
When you visit any website, it may store or retrieve information on your browser, mostly in the form of cookies. This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The information does not usually directly identify you, but it can give you a more personalized web experience. Because we respect your right to privacy, you can choose not to allow some types of cookies. Click on the different category headings to find out more and change our default settings. However, blocking some types of cookies may impact your experience of the site and the services we are able to offer.
More information
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then some or all of these services may not function properly.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising. Some 3rd party video providers do not allow video views without targeting cookies. If you are experiencing difficulty viewing a video, you will need to set your cookie preferences for targeting to yes if you wish to view videos from these providers. Unity does not control this.
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. These cookies do not store any personally identifiable information.