3dsmax ambient occlusion bug?
polycounter lvl 18
This is a new one that cropped up today and is killing me.
I need to render ambient occlusion using render to texture. No problem so far. Ive done this a lot before so I know the steps.
Weirdly, my results today show black wherever the low res model intersects the high (?????!!!!) This would mean that mental ray is now including the low res mesh in its calculations. AAHHHHHHHGGGGGG!!!!!
Is this just me or is this now a critical bug?
I need to render ambient occlusion using render to texture. No problem so far. Ive done this a lot before so I know the steps.
Weirdly, my results today show black wherever the low res model intersects the high (?????!!!!) This would mean that mental ray is now including the low res mesh in its calculations. AAHHHHHHHGGGGGG!!!!!
Is this just me or is this now a critical bug?
Replies
I'm pretty sure you must have tried resetting xforms/checking your normals, right?
I seem to vaguely remember having the same problem with rendering AO maps with mental ray myself as well.
Question: Why is everyone using mental ray to bake AO when the skylight + advanced lighting solution works fine? You can set up all sorts of nice bounce lighting and tweak the settings in there for a nice fast and high quality bake, and it doesn't take ages to set up - just add a skylight, set its colour to white, turn on Adv. Lighting, set the rays down from 250 to 50 or something and bake it... I haven't had any problems with that.
Is there something mental ray does noticeably better or faster?
1-When bake Ambient Occlusion with mental Ray Occlusion shader for light(NOT Global Illum. like lightracer do, ITS DIFFERENT Things) in objects properties of your low-poly UNCHECK in Render control all radio buttons exclude Renderable(if ucheck- bake to texture will fall everytime)
Your low-poly will renderable but not visible in render frame window(is it bug of MR working with BakeToTexture?)
2- Ambient occlusion is procedurical shadow, its show places where light is attentuate(fall off?? Sorry my english Im from russia))) and its work something like dyrt, its not lighten deep places even light point directly cast light to it, GI instead can lighten deep places of your object.
AO generated by every part of your model? in max you can setup spread angle, the more rays casted from every point of your model hit surface- the more darkly this part of surface. Flat surface with spread <0.9 will bright, more 0.9 it will self shadowing(dont use more than 0.88)
Thats why Ambient Ocllussion more preferable then GI type of light.
Ok, the way to do this is to use the G-Buffer.
Set your low poly objects G-buffer to, say, 15.
Then in your Ambient occlusion map set the include/excl. Object ID to negative 15 (-15).
This will then exclude the low poly from the shadow solution.
The previous suggestions about turning off object property renderable etc does not work.
Hope that helps anyone out there from pulling out their hair.
the key is that the cage can not be reset. it needs a value over 0. OR you could use
an offset in the optons setup of the "render to texture" dialog.
here is a nice tutorial: http://www.ai-dallas.com/student/Haydel/RH/uploads/Ambient%20Occlussion%20Maps.pdf
mabye this still is interesting for some people..
cheers
Could you please elaborate? The link you gave no longer works. How do give it a value above 0? The Push amount always goes back to 0. The offset option also did not seem to work for me.
I've tried so many methods but all I'm still getting is ray misses (red spot) on my baked AO texture. I've been using the skylight scanline method for a while now, but there are situations where MR's AO is better. So that's why I'm re-exploring this option.
I've tried this
(http://forums.cgsociety.org/archive/index.php/t-560767.html) but still had the red errors.
I would also like to know how King of Daveness used object ID to solve it. I can only find the option on the mental ray AO material but not in the render to texture option box.
Any help would be appreciated. The funny thing is that it works with some object but not others.
regards
The other issue is about MR taking the lowpoly in account while rendering.
The options are in the object properties. I think putting visibility to 0 works, as assign a different gbuffer ID.
Yep. I have ensured that my projection cage is pushed out far enough. I also tried using the "CompleteMap" baking option and followed King of Daveness's object ID trick. I placed a standard material on the highpoly model and in its diffuse box, gave it the AO material. I gave the low poly model an object ID of 10 and in the AO material's dialogue box, I gave it a -10 for the exclude object ID value.
None of that seemed to work. I'm still getting ray miss red spots. Basically this is the EXACT same problem as I had mentioned here back in 2011 (http://www.polycount.com/forum/showthread.php?t=91576)
It's as if the baking process no longer listens to the projection cage but to the geometry itself! It seems to be a problem with the projector and nothing else. I hope Newton could shed some light.
Using scanline renderer with skylight is almost 100% trouble free. But as stated in Lauren's tutorial, intersecting geometry is not anti-aliased. Mental Ray does a much better job in corners and very confined places.
(http://www.laurenscorijn.com/articles/ambient-occlusion-baking)
The funny thing is that it seems that some people on the net seem to be able to get it done on a reliable basis. I was also wondering if this process is less painful in max 2014?
Is the Ambient occlusion (MR) option in the Render to Texture option really that broken?
Anyway, I've attached some files. I hope someone could take a look at them. Thanks in advance.
Any input would be greatly appreciated.
Regards
GIS3000
Yes I have reset my Xform.
But after more experimentation, I've been able to solve my issue, thanks to you.
It's the VISIBILITY! Nothing else mattered but that!
Once again, thanks for the help. Baking AO from a highpoly to a low poly using mental ray is now an option!
Regards
GIS3000