View Full Version : Ao problem?

04-27-2009, 09:20 AM
Hi guys a little question. Is everything working ok for you with the build-in AO in mia_material? Every settings I try I get no AO contribution. The AO is enabled in the render manager and also in the render region.
Thank you very much!


04-28-2009, 07:48 AM
Ok, here is a little test, compared with maya.
The scene is a "cornell box". The box edge is 20 SI (so it will be 200cm). Scaled in Maya to obtain the same scale.
All the materials, are mia_material. Settings of the mia_material in maya and XSI:
Samples 16
Distance 1 (in maya due to the 1:10 scale)
Shadows color 0.2
Ambient color 0
In this test changing the detail enhancement in XSI doesn't change anything! If I open photoshop and put an image over another ans set the blending mode to difference I get a complete black image!
The ambient occlusion is set to "on" in the render manager.
I forgot to tell that I'm using XSI 7.5...
Someone have an idea of what is going wrong?

04-28-2009, 12:15 PM
Another test. With the physical sun&sky everything seems to work great...

04-29-2009, 12:06 PM
Can you try to put a very long distance such as 1000 to see if you got something ?
By the way on your sky+sun render when detail AO is activated you can see the difference with the others pictures ( specially under the rock )

04-29-2009, 01:59 PM
If I put 1000 for distance I get a darker version of the previous render so I can think that the AO is calculated (if I look at the render times when AO is on it gets longer to render so it must be this). With the sun&sky the result seems to be good, but why with it it works??? I'm doing something wrong?

04-29-2009, 09:45 PM
built-in AO works only on AMBIENT COLOR so, you either have to have

- FG or GI enabled with detail enhacement on 1 (standard ao) or 2(color bleed)

- or ao ambient color set to something else than black,
detail on 0/1 and a light with shadows on ( you will see ao effects only on lightened by ao ambient shadow parts!). You can set detail to 2 but results will be funky.

AFAIK mia_mat ao was designed to work best with FG.

same shit applies to arch material in MAX, dunno about Maya but all apps share same mentalrays .dll's so theoreticaly they should work identically.

CGTalk Moderation
04-29-2009, 09:45 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.