unified sampling render and AO pass

[SgWRX]

i'm finding that with MaxDesign 2015 and unified sampling, i'm having to up settings to quality=2.0 min=1.0 max=256, filter=gauss and contrast/noise (spatial) = .005 rgba to help reduce AA flicker within some bushes and grasses for a particular animation i'm working on.

 

i also thought about an AO pass and i took the path of a material override with mentalray material and AO shader in the diffuse slot. the AO shader looks fairly grainy with the 16 samples, so i've upped it to 128 samples. then i've applied the same rendering settings as above.

 

one question i have is whether these settings are overkill? i notice that on one machine doing the AO pass it is taking 28mins per frame, where the color beauty render on the other machine is about 5mins per frame. this 2nd machine is normally twice as fast as the 1st.

 

another question is, if my sample settings in the AO shader exceed the sample settings in unified sampling, is that a waste of time? i realize it's not happening in this case but it's more of a general question.

thanks,

[Francisco Penaloza]

In theory, you should not change any sample values in your scene, leave everything to default and only work with unified sampler. This new AA system will sample your scene and apply the necessary amount of AA to each element, depending of the contrast values that you can setup.

When you put more samples in your materials, you are forcing that materials to try to reach that value. This can help the unified system but it may be unnecessary. By my test I don't have a straight yes or not, by the manual it is unnecessary.

 

Your value of quality 2 is OK, it may be a little lower actually depending of your scene. Do not be afraid to use bigger values, but then you'll will have to trade quality Vs render speed.

 

Using an over all AO is a little bit over kill in my opinion, I rather use the build in to the shader AO for the materials that I want to have a better accent of soft shadows, using AO for the whole scene will take longer to render because meshes such grass and trees will apply this effect to every single element, witch in reality is barely visible, mostly in animations.

 

What type of GI are you using? IBL or traditional FG?

IBL will require more samples to clean.

[SgWRX]

thanks! for one particular render i was doing traditional FG with unified sampling. i just did another render today and used IBL with a higher shadow quality (1.0 vs. .5 default), unified at quality 2.0, min=1, max=256.

 

today's render i used built-in exact AO with the a&d material. these unified settings seem to be cleaner than the default settings, but still some AA noise going on especially in the AO portion.

 

in theory then, unified sampling would also apply to the AO shader built into the A&D materials or any shader.

 

i'll do some more playing around with it tomorrow in terms of JUST playing with the quality settings and spatial contrast settings. i do know for sure that motion blur effects are much quicker with unified sampling as was pointed out a long time ago when it first became available.

 

for bushes and trees i tend to turn them off for global AO override material, or i've tended to just use these for still renders and therefor not had too much problem with speed due to almost default samples.

 

thanks,

[Francisco Penaloza]

Regarding the unified sampling, usually you should increase the Quality values and reduce the contrast threshold before you decide to increase the Max, the default 128 will produce clean images most of the time. if you keep the quality low 1 or 2 it really does not matter how much you put in the Max value, the system will never reach that.

The unified AA will take care of all dynamic AA work in mental ray. AO samples, Blurry reflections/Refraction. Motion blur etc.

Animations with small objects such, tree leaf or grass, usually needs higher AA samples, Thin object or patterns also require height AA compared to regular still images.

 

Besides that you have shadows precision for IBL and reflection Refraction Global multiplier, The main idea is this should be your one stop to tune your quality renders.

I guess if you work with REVIT Autodesk materials, this will be essential. since those materials are horrible to work otherwise.

[SgWRX]

got. and i did some renders of a metal roof with max 128 vs. max 256 but the 128 was higher quality, the result looked fairly similar (gloss reflections). i think i got a good handle on it, that as quality increases you get closer to max samples. but i guess u have to include the contrast settings too.

thanks,