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Mixed lighting using probes and baked GI vs Realtime lighting with Realtime GI

Discussion in 'Global Illumination' started by mrCharli3, Jul 10, 2019.

  1. mrCharli3


    Mar 22, 2017
    I am wondering if someone can explain which is the better for performance between these two options, for an outdoor scene with a few hundred objects, many of them just foliage and rocks. But surrounded by huge mountains and large terrains.

    1. I use mixed lighting, marking my mountains and other large objects as lightmap static, using baked GI for these. But leaving grass, rocks, and trees (trees dont bake very nicely for some reason) as lightmap dynamic, and instead use probes to get bounces on these objects. Do I even need light probes when using mixed lighting, or is that only for when using purely baked?
    2. I use Realtime lighting (which I dont really need since my sun is static), and bake everything using realtime GI.
    Unfortunately simply baking everything using mixed/baked GI is not possible for me it seems, to reach the results I want I need to use a resolution that crashes unity after a few hours. So I thought option 1 was a clever compromise, but not sure if it will actually make a difference on performance compared to option 2, which is a lot easier to manage.

    I have a very bad grasp of how different lighting effect performance, except that baked is better than realtime. But I think in most scenarios it's not that black and white, like in mine.
    Last edited: Jul 11, 2019
  2. kristijonas_unity


    Unity Technologies

    Feb 8, 2018
    If the sun in your scene is static, the first solution will provide you with the best looking results and biggest performance gains. Realtime GI incurs some additional cost on top of paying the price for realtime lighting.

    With mixed lights you will get an added benefit of being able to use shadowmask textures, which will allow you to have high resolution realtime shadows up close, and baked shadows in the distance. You can also save quite a bit of lightmap space and baking time by reducing lightmap resolution, as baked indirect lighting does not need to be very defined.