I am compositing a modeled sea scene in AE. Here's what I have:

enter image description here

Adding in my AO layer gives nice strong shadows as shown: enter image description here

However it also covers my blue sea (primarily an AE 4color background)....

How can I keep the AO benefits to the shadows on my critters, but also keep my background?

As rendered, I have alpha, color pass with alpha, AO and depth (which is driving AE lens blur). I can render anything else needed. enter image description here

1 Answer 1


Let's try to make it work. :D

1) Place 'Alpha' layer above 'Ambient Occulsion',

2) Change setting in 'TrkMat' of the layer 'Ambient Occulusion' to 'Luma Matte'

if Luma Matte is not working, try with 'Alpha Matte' (I'm not sure about your alpha layer :)), trkmat

3) Precompose 'Alpha' + 'Ambient Occulsion' layers ctrl+shift+c,

4) Set precomposed layer to 'Multiply' Mode.


  • Absolutely perfect! It was Luma matte that worked, as you suggested... And the solution worked without precompose, and this probably points to something I still do not understand about AE: What additional benefit does precomp offer beyond just stacking things where they are? But THANK YOU !
    – rcgauer
    Commented Jun 23, 2018 at 12:36
  • Precomposing is just collapsing layers into one, in this example I recommend precomposing, for cleaner workflow. becouse propably you are not going to modify alpha channel in AO :D
    – gadas_
    Commented Jun 24, 2018 at 15:22

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