The 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 Progressive GPU Lightmapper is a backend for the Progressive Lightmapper that uses your computer’s GPU and VRAM generate baked lightmaps and Light Probes.

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.