Answers.Body: <h2>Let's try to make it work. :D</h2>
  
  <p>1) Place 'Alpha' layer above 'Ambient Occulsion',</p>
  
  <p>2) Change setting in 'TrkMat' of the layer 'Ambient Occulusion' to 'Luma Matte'</p>
  
  <p><em>if Luma Matte is not working, try with 'Alpha Matte' (I'm not sure about your alpha layer :))</em>,
  <a href="https://i.sstatic.net/ltpmK.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ltpmK.png" alt="trkmat"></a></p>
  
  <p>3) Precompose 'Alpha' + 'Ambient Occulsion' layers <em>ctrl+shift+c</em>,</p>
  
  <p>4) Set precomposed layer to 'Multiply' Mode.</p>
  
  <p>Done!</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-23T12:36:25.313Z
Answers.Text: 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 !
Answers.UserDisplayName: rcgauer
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-24T15:22:11.313Z
Answers.Text: 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
Answers.UserDisplayName: gadas_
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-23T10:21:00.610Z
Answers.LastActivityDate: 2018-06-23T10:21:00.610Z
Answers.UserDisplayName: gadas_
Body: <p>I am compositing a modeled sea scene in AE. Here's what I have:</p>
  
  <p><a href="https://i.sstatic.net/4N3xE.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/4N3xE.jpg" alt="enter image description here"></a></p>
  
  <p>Adding in my AO layer gives nice strong shadows as shown:
  <a href="https://i.sstatic.net/HZkB3.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/HZkB3.jpg" alt="enter image description here"></a></p>
  
  <p>However it also covers my blue sea (primarily an AE 4color background)....</p>
  
  <p>How can I keep the AO benefits to the shadows on my critters, but also keep my background?</p>
  
  <p>As rendered, I have alpha, color pass with alpha, AO and depth (which is driving AE lens blur). I can render anything else needed.
  <a href="https://i.sstatic.net/Q9kBj.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Q9kBj.jpg" alt="enter image description here"></a></p>
  
Tags: <after-effects><compositing>
Title: Adding AO render pass in After Effects
UserDisplayName: rcgauer
ThreadText: # Adding AO render pass in After Effects
  
  (Asked by: username_0 on 2018-06-22)
  
  I am compositing a modeled sea scene in AE. Here's what I have:
  
  [![enter image description here](https://i.sstatic.net/4N3xE.jpg)](https://i.sstatic.net/4N3xE.jpg)
  
  Adding in my AO layer gives nice strong shadows as shown:
  [![enter image description here](https://i.sstatic.net/HZkB3.jpg)](https://i.sstatic.net/HZkB3.jpg)
  
  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](https://i.sstatic.net/Q9kBj.jpg)](https://i.sstatic.net/Q9kBj.jpg)
  
  **Tags:** after-effects, compositing
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2018-06-23. Score: 3 | Accepted answer
  
  ## 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](https://i.sstatic.net/ltpmK.png)](https://i.sstatic.net/ltpmK.png)
  
  3) Precompose 'Alpha' + 'Ambient Occulsion' layers *ctrl+shift+c*,
  
  4) Set precomposed layer to 'Multiply' Mode.
  
  Done!
  
  > **Comments:**
  > **username_0**: 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 !  
  > **username_1**: 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  
  
  ---
  
  