View Full Version : combining AO and beauty passes

01 January 2009, 05:17 PM
I've just started to use 3Ds Max and in the process of rendering out ambient occlusion and beauty passes into separate folders to then combine for a short animation.

If someone could please give advice on the following:

1) Am I going about this the wrong way?
2) I'm considering using Blender's compositor for this as I'm only likely to be using it for similar tasks. Could anyone recommend other open source/free (prefered) compositors?
3) Could anyone recommend easy to use (but possibly limited) licensed software suitable for my needs?

Any help would be greatly appreciated.

01 January 2009, 11:54 PM
I use AE so am unable to answer on other apps.However,what you need regardless is the ability to be able to multiply your AO layer over your Beauty pass similar to photoshop layer blending should ask on the Blender forums.I've never used it as i'm a Max user but have heard amazing feedback on all aspects of it's design and constant open source upgrading capabilities driven by it's ever epanding artistic R&D userbase.

01 January 2009, 04:19 AM
Not sure about Blender, but just about any decent compositing package will allow you to do so:

After Effects

All you need, is to blend the AO pass over the Beauty pass using the "Multiply" mode... this will enhance the shadows and contrast in the animation, adding more"depth" to it...

if its a still image, Photoshop can be used...

01 January 2009, 04:44 AM
Thanks for your help :) Will give Blender a go and look at AE or Nuke later.

01 January 2009, 05:30 AM
It really depends on the look that you're going for or that you're happy with. Technically it's called 'ambient occlusion' as it's only meant to attenuate 'ambient light'. Multiplying directly over a full beauty pass generally leads to a 'dirty' look. Sometimes that is what's desired though and that's fine.

It's all dependent upon how you want it to look. In the end if it looks right, it's right. If it looks wrong, it's wrong.

01 January 2009, 02:26 PM
hey llihneb!

listen to 1armedScissor! he's totally right and of course there a people going for the "look" but as you wrote, you're about to start using max and maybe you're starting with compositing, too... so, to understand this ambient occlusion thing a little better and see what's the "dirty" look, check this:

have fun!


01 January 2009, 07:03 AM
thanks 1armedscissor - before posting I did a quick multiply trial in photoshop and noticed that it did look a little dirty and thought to myself: "I'm waiting 1hr15mins for the two renders and it looks like this?!". Grainy.

chemkid - thanks for the link that explains the reason for this.

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