Oh, the humanity! (Maya 2015 Finag Gather Woes)

#1

So…

For a couple of years I have been using vRay for product viz stuff. Recently a colleague of mine was working on an interior in Max, with vRay of course and had really long times. So having seen the Maya 2015 release I decided to download the trial and try out the new mental ray and the mila materials… but boy was I in for some pain and humiliation.

Final resolution was 1920 x 1080

Screenshot:

There are only two large openings - you can see the mr sun shining through one of them. The second is exactly identical only opposite. Two portal lights - custom environment ticked on - the default mr sky connected (the one created through render globals). Lights are set as visible both in the mr tab of the shape node, as well as the portal light shader. Both lights use the same portal light shader.
FG settings: Accuracy 512, point density .512, Interpolation 30. Filter set to 0. I think that everything else is default.
Material: default mila diffuse with a .5 value.
Geometry pretty basic. Few polys for now. No smooths applied.

So what the h… does one have to do to get a cleaner GI solution?

The unified sampling quality parameter in render globals is set to .25, but that shouldn’t affect the FG calculation as far as I know.

#2

Your FG point density is pretty low for subtle FG shadow effects. Try 5 or more and consider adding AO in RenderGlobals.

#3

5, really?! :open_mouth:

#4

Yeah i know every tut etc. uses pretty low values but consider that the point density is the amount of sample points used from where mr starts to generate the diffuse calculations (the amount of rays spread from there is the fg accuracy). So although the docs say nothing about what the value of point density really means i think much more of such points should provide a much better fg shadow effect after fg point interpolation. You even could disable the interpolation of your fg sample points if you set the fg mode to “No FG Caching”. Then every shading sample gets its own bunch of accuracy rays.

#5

At the risk of starting a FG debate. I disagree with the advice of increasing point density. For me, FG is not a good source of high detail global illumination. I would leave all the settings at default except set the interpolation quite high(perhaps 100 or more), especially in scenes where the majority of the light is from a small source. This will blur the FG but also will remove blotchy artifacts and FG flicker.
As far as using ambient occlusion I recommend using AO in the mia_material to bring back the detail lost with high FG interpolation values.

#6

I agree with Will there, I would suggest lower FG settings (point dens: 0.128 , accuracy : 128, filter : 1, leave interpolation at 30) and resolve the detail in the shader. But even better than AO , in the MILA library use “mila diffuse detail” ON , which now replaces the mia_AO. Its basically brute force path tracing with a distance limit using the “mila diffuse detail distance” attribute.

Read here http://docs.autodesk.com/MENTALRAY/2015/ENU/mental-ray-help/files/shaders/layering/components.html

#7

Very nice! Keep your opinions coming! :slight_smile:

Update: tested this with point density 3 - basically the same, 3x render time.

LinchpinZA - are those unexposed global string options? Because they’re not in the material.

Thankies!

#8

Yes you would have to add the attributes as strings to your “Diffuse Reflection Component” shader.

String:
“mila diffuse detail”
as a boolean, on or off. Default off.

String:
“mila diffuse detail distance”
as a float, default 10.0, min 0

#9

This worries me a little since big planar surfaces will still present splotches - a more realistic FG setting for me would be something like point dens: 0.128, acc: 0.128 but interpolation something like 60, or 100.

Will test this shortly.

#10

Yeah maybe I’m remembering incorrectly and I used to up my interpolation a lot higher than that, I also remember going as low as 0.06 point density for some arch viz scenes.
As long as you have the detail distance thing there to accentuate corners/crevices etc.
The max distance will depend on your scene scale, that measurement is in scene units.

#11

Ok, pushing one more - I hope you don’t mind: would you say right now that you prefer this workflow (low fg, high interpolation, mila shaders with detail distance) to the older one, with MIA materials and AO detail distance? Would you then say that you prefer this workflow to what vRay has to offer with Irradiance and Light Cache?!

#12

I don’t think my opinions on this topic has any value at the moment because I haven’t tested the new MR features with enough complex scenarios to say whether these workflow’s are better than the old ones or how they compare to vray etc…

It is still doing a lot of approximation(lowQ FG everywhere) which is never good in terms of physical accuracy…
I also haven’t tested the whole unified sampling setup in mentalray enough, where you
pay close attention to your global ray counts and tweak quality on a more global scale
(this seems to be the way MR is heading, simpler control etc.)

At the moment my opinion of FG is that it’s like a poor mans lightcache, much less flexibility than vray’s lightcache. In vray I prefer going bruteforce&lightcache I can get
render times decent with no flicker but I always know I can probably get rendertimes really
low and flicker free in MR, albeit in many more clicks.

However, I am paying close attention to mentalray, MILA is awesome, indirect GI is still lacking a bit, but vray is still my prefered choice at the this point in time. Mostly because of it’s quicker out of the box workflow(one that stands out is proxy setup time, takes muuch longer in mentalray.)

#13

You do not need to use MILA for this… unless you plan to use layered shaders extensively in this scene. My suggestion would be this:

FG rays: 100
FG point density: 0.2
FG interp. points: 30
FG filter: 0
FG diffuse bounces:1

Then put mia_material_x on everything, and enable AO detail enhancement (not just AO) and make sure that AO shadow color is set to black. It’s very important. When you use just AO mode, increasing shadow color increases shadow brightness, but when you use detail mode, increasing shadow color actually makes AO darker! So make sure it is black.

And set radius to AO detail mode to something like 0.5-1 meters, assuming your scene is in the correct scale.

#14

So, yeah… this is lightning fast. And I do admit, with something like this I am very familiar.

But I would like to try a comparison. So - does anybody know how to correctly use detail distance with MILA materials?

PS: will render something tomorrow morning, curious to make that comparison happen. But, before that… unified sampling kinda does that nasty board game trick with a ‘return to position 0’ action. I find it kind of hard to control it. When I left mental ray a couple of years ago it wasn’t officially released… :slight_smile:

#15

I think it will be cool to test this and compare this.

I will try do some test renders in the next day or two and will post them up here.

Maybe have a few case scenarios, scene with no layered materials VS scene with layered materials VS scene with a mixture of layered and non layered materials…

#16

Quick test here with MIA material:

Full HD frame rendered in 11m25s… not that bad.
FG settings this time were: acc: 256, density: .256, interp: 75, diffuse bounces: 1

But! I still can’t get rid of the grain - quality parameter of the unified sampling setting was set at 1.

Still haven’t figured out MILA workflow with detail distance. Once I do I will properly test this (maybe this evening?!)

Ideas on the MILA workflow anyone?! Tips on unified sampling?

#17

Does the graininess go away if you set FG filter to 1?

#18

No, the graininess has to do with area lights sampling and the AO detail function of the MIA shader. I have to go mad on the rays on those to get the image to smooth out.

#19

I was not interested in your opinion.

#20

Dumb question of the day: assuming one uses portal lights, which by definition need to be visible - how then does one render the outside geometry if the portal light would only display the environment shader?! :smiley: