AO Issues


I’m working on a scene (tutorial) and I’m having issues understanding the Ambeint Occusion. Here are two shots of my scene.

First AO on, factor of 1, blend mode: Add:

Second without AO:

In Both shots I have two lights: 1 Sun Lamp (in the rear facing the camera) and one spot light (camera right facing into the scene).

So my issue is that I like the shadowing etc of the AO but it lights my scene too much and at that point my lamps seem to be ineffective. Not sure why this is happening.

Here is a screenshot of my setup (top view down). You can see the Sun lamp in the upper left corner and the spot light in the opposite corner.

And finally a shot of my composite nodes:

So I’d ultimately would like to use AO and get better control of my lights for a much more dramatic lighting of the scene.



First AO on, factor of 1, blend mode: Add:
You would generally use the Multiply blend mode with AO

Hey Richard, thanks for the reply.
I tried that and my scene comes out really dark. I just did another render below (lower angle). The spot light on the left of the camera is pointing into the scene and at an energy level of 5 which seems very high, but as you can see, the scene is still very dark… still confused…


You’ll have to adjust your lighting then.
AO is generally there to give fake “shadowing” in the areas where objects are close to each other (nooks and crannies). It is not controlled in any way by lamps and lighting.

I’ve had the same issue and the only solution is I almost never us AO set at a power of 1.0. Usually I go with 0.5 AO and 0.4 Environmental lighting using sky color. Multiply is very strong and not matter if you set it to 0.1 or 1.0 it will still be black because the darks are the only thing being multiplied:( Anyway thats my experience, looking at you render and it resembles a scene Andrew Price did for the NA. Was that intentional? Are you in the Nature Academy or just trying to do it solo? If so check out the Blending Nature thread in the WIP forum where we are working through the nature aspects of Blender as well:)

Happy Blending!

Well, what ambient occlusion is, if you don’t get it, is just a method of introducing ambient light to a scene (hence the name). It does this by figuring out how far away different surfaces are from each other and adding more light where they are farther apart. To fix your issue, I’d recommend just playing with the values of the ao and the lights until you get the result you’re looking for. And maybe it’s just me, but your trees seem specular.

Okay - I think I figured out the problem:

I changed from Spotlights to Area lights and things are looking better - I guess I don’t really understand how spotlight and AO work together - or if they do at all…

Thanks for the direction!

Hey Derek! Yes I’m am doing the Nature Academy and loving it - I posted here since my question was more broad about AO, nit so much about the tutorial itself. Also didn’t think this was the correct place to plug Andrew’s Course :wink:

Hey GraphiX,

I just wasn’t getting the control I wanted with AO and ADD, but AO and Multiply plus lots of tweaking of Lamp objects seems to have done the trick.

So are my trees “specular” or “spectacular” :slight_smile: — yes specular, I’m trying to get an overall wet look to the scene.

Well, good thought process. But, either too much specularity, or it’s just not the right way to do it, imo.

Here is a render before my compositing nodes are applied - the specular on the trees looks better here, but I want to have and over all fantasy feel to the scene… almost there…


PS: I thinks it’s fog layer in the nodes that’s causing this…