topic Re: Adding AO to a render without compositing? in 3ds Max Shading, Lighting and Rendering Forum

Adding AO to a render without compositing?

Anonymous — Thu, 12 May 2016 03:09:31 GMT

Hi,

Normally, to add Ambient Occlusion (AO) I do one 'standard' render and then a 2nd render using a Mental Ray > Ambient Occlusion material in Render Setup > Processing > Material Override. I then composite these 2 renders together in post. Sometimes I'll use Render Elements to render out both but that still creates separate images for passes, which still need to be composited together.

I'm wondering if there is a way to add the AO pass directly to the diffuse pass so I don't have to composite them together in post.

Thanks.

Re: Adding AO to a render without compositing?

darawork — Thu, 12 May 2016 14:52:02 GMT

Hi,

I add AO the same way you do it, but there is always this way too: https://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/3DSMax/files/GUID-6F8332A7-CD75-4DA6-9E91-3A167B847A44-htm.html

I've not really tested this option a lot, so I'm not sure if it achieves the same intensity as doing it in post.

Re: Adding AO to a render without compositing?

Anonymous — Thu, 12 May 2016 17:52:02 GMT

This will be interesting to play with but I'm not sure this is what I'm looking for as it is at the materials level. This would be troublesome for a variety of reasons, including that I'd have to redo all the materials in the scenes and would not be able to easily tweak the AO for the entire scene, as you can do when you use Material Override or Render Elements, which reference one single AO material.

I was kind of hoping there would be some checkbox or something in the render setup that would automatically combine the passes into one image. In my head, this doesn't seem like an outlandish request as 3ds Max already has all the information... I just don't want the information saved as two different images.

Thanks.

Re: Adding AO to a render without compositing?

Richard.Vivanco — Fri, 13 May 2016 02:34:55 GMT

In mentalray you can enable AO material by material. Look at the special effects rollout in arch&design material. Then enable ambient occlusion and configure it.

This method increase the rendering time.

Good luck

Re: Adding AO to a render without compositing?

Anonymous — Wed, 18 May 2016 18:50:25 GMT

Yeah, that's what we were talking about in the previous two posts. An AO buried inside a material doesn't work for me because I have a ton of different materials and I would not be able to tweak the AO for the entire scene using the Arch&Design material.

Any other suggestions?

Re: Adding AO to a render without compositing?

yassina — Wed, 18 May 2016 19:19:45 GMT

There is a bit of a "sneaky" way, by using the Ambient Projection properties of an Omni light. Basically, you create an omni light at 0,0,0 and you set it to affect the Ambient properties of the scene only. You then assign an AO map as a projection map to that light in the Advanced Effects rollout.

I did a tutorial about this some time ago, it's a quick way to get decent results.

You can check the tutorial here:

https://www.youtube.com/watch?v=uKaKlOb_ySQ

I hope it helps.

Re: Adding AO to a render without compositing?

jenni.oconnor — Wed, 18 May 2016 19:38:55 GMT

Hi,

Another thing you can do involves setting up a small MAXScript tool that I've attached, Macro_mrArchMtlTools.mcr.

Unzip the attached into a folder. Drag-and-drop the mcr file into a Max viewport to place it in your installation. You then need to add it to a menu to access the tool.

Go to Customize->Customize User Interface, switch to the Menu tab, and change the Category to "mental ray":

You should see the "mr Arch & Design Tools" on the left; drag it into the Rendering menu on the right. Close the dialog box.

You can now select the new menu option and you'll get this:

You have buttons to turn on and off AO for all A&D materials. Let me know if this works for you!

- Jenni

Re: Adding AO to a render without compositing?

Anonymous — Wed, 10 Oct 2018 10:16:22 GMT

Have seen many of the tutorialss you have created, thank you learning a lot from them all the way...

You mention "create an omni light at 0,0,0" This is not reflected in the tutorial however.

What difference would this make?

So in conclusion: with this solution the lights and shadows are not physically accurate right? so in all final renders that we want to get as real looking as possible, we would either have to resort to

Option 1: setting AO on the material level or

Option 2: composite the image in a 3rd party compositing software, right?

Rgds,

Andro