Daz 3D is part of 
Connect
DAZ Productions, Inc.
7533 S Center View Ct #4664
West Jordan, UT 84084
Licensing Agreement | Terms of Service | Privacy Policy | EULA
© 2025 Daz Productions Inc. All Rights Reserved.
Comments
As a proof of concept, I had edited IrayUber shader (not the MDL) for just volumetrics, and kept the refraction weight, index, and color input nodes intact. I also left in Abbe, and a few other things.
As I noted above, you can get a noise texture by plugging it into the Refraction Color node.
The "problem" is that the volume brick is downstream of everything -- it appears right before the render stage. The refraction color first goes through a refraction map brick, then to join into what looks like a T-bridge, the metallacity base. (As I'm a beginner with these brick thingies on not clear on the terminology!).
Here's a test render with my modified UberShade that has all the nodes removed except the ones I felt critical to this process. I didn't render this with the texture input, so it's straight volumetrics. (As a side note: this volumet stuff really taxes the old CUDA cores.) Being able to use a texture map is, I believe, crucial. Not just for noise, but for general effects, such as exhaust plumes.
In case this is useful, what's the EULA restrictions for posting a DUF or DBM that's been modified from a Daz asset? Can these be shared?
Looks like there isn't any absorption or scattering happening there. I may can help you out to optimize that. At least for the absorption coefficent.
Taken from the article "Journal of Heat Transfer, November 1982, Vol. 104/602-608 "Evaluation of Coefficients for the Weighted Sum of Gray Gases Model", that for water vapor, at a pressure of 1 atm (atmosphere), would be around 0.4496 (per meter), and for a water vapor/carbon dioxide mixture around 0.4303 (per meter). Since DAZ seem to already have adjusted their Iray renderer-plugin to the default 1 cm per unit Studio world scale, I'd go with a 1.0 for "distance_scale" in the MDL and a 0.001 on the Shader Mixer in Studio. That way your work would be of universal usability for any Iry version.
GPU Gems 2 has an article about Accurate Atmospheric Scattering. Some of the listed "References" are dead already, but the "Rainbows and Fogbows: Adding Natural Phenomena." by Clint Brewer is still available and looks interesting at the first glance. Maybe you find something useful in there for your project.
Cheers
I'd say, since it says at the top:
"Copyright © 2015 DAZ 3D, Inc. All Rights Reserved.
This file is part of the DAZ Script Documentation.
This file may be used only in accordance with the DAZ Script
license provided with the DAZ Script Documentation.
The contents of this file may not be disclosed to third parties,
copied or duplicated in any form, in whole or in part, without the
prior written permission of DAZ 3D, Inc, except as explicitly
allowed in the DAZ Script license."
I'd take a look at that first. Just to be on the safe and sunny side.
Wrong file -- that's the MDL. There's no copyright preamble to the IrayUber DUF, or DBMs generated from existing assets. I'm wondering if it's the same as file with a morph controller that contains the original morph.
Not sure if this comment was in response to my sample at the top of the page, but the volumetrics are there. I simply dialed in large values intentionally to speed up the render. It's a 1meter sphere, and I put both values at 2 meters, as shown in the shader panel
Spheres are actually not all that good for demonstrating volume effects. I've attached another example of a cone, with distances set to 50cm. The apex of the cone, and the thinnest part of the volume, is right in front of her.
Thanks to jag11, I have Image inputs at least wired up. Removing the uniform keyword and a couple of new bricks takes care of that.
Actually plugging in a texture, though, makes Studio crash. I'll give that a try again later this evening. Suggestions?
Tobor pointed out this post the other day. The item of interest to me is the equations lifted from Iray Uber:
My question, since I'm not familiar with the physical processes, is this. Is the logorithm used above simply to make a more granular range of values available in the result, or is it a fact of nature?
I need to get some dinner. I'll report back on the noise texture when I have some results.
P.S. And why do code snippets display in such a huge font?
Nice work!
I'm currently doing a very long 3000px render, and when I can I'll experiment a bit with the toolset I've made. But to answer the question about the math involved, I would think this is material specific. That said, when I rendered side-by-side orbs using IrayUber and the wax snippet, they looked pretty similar. The renders weren't high def, and I only let them go to about 40%, so maybe in a fully-rendered scene the differences in the math between the two MDLs is more apparent.
On the crash, I'm guessing at this point, but I wonder if the image needs to go into only one term, either absorption or scattering, but not both? For that matter, what happens if we have different maps for each?
So ... we can copy and paste code to make the MDL, but is there a way you can save the brickset and post it here?
Basic Volume (works)
Intermediate Volume (crash)
I was only using one texture map at the time, for scattering. I'm stepping back on that and taking a closer look at noise textures.
Noise texture also causes crash just as render starts.
Update: Bug report filed. I'm probably doing something stupid, but it still shouldn't crash.
Noise Volume (also crashes)
Any suggestions?
I'm away from my computer. I'll give it a try later.
No crash here. Use these values to actually generate visible perlin noise. I did some tests and found that plugin in perlin noise generator to the SSS Amount has no effect.
Yep. Still crashes. Apparently OS X specific. I'm running latest NVidia webdriver and CUDA. Looks like I'm toast on this until somebody fixes something.
Update: Definitely a Studio problem. Still crashes on a Mac with no NVidia/CUDA. Looks like they're overrunning a buffer on the stack.
That's weird, I'm always working with Iray preview on. The only time DAZ Studio crashes on me is when I use Geometry shell and export to Hexagon, no matter what figure or shape I work with.
What if you just render with CPU only?
I rendered on a completely different computer, a laptop with no NVidia card. It still crashes.
It's getting a SIGBUS in one of the threads running libiray.so. This is always a programming error. I thought initially that they were overrunning a buffer because of the stack canary message, but looking closer it's more like they tried to access data on an improperly aligned address.
If the above sentence is gibberish, please ignore it. If you're a software engineer, I'll gladly provide more, but it might injure others in the thread.
What's gibberish?
Just shoot. I speak several languages, from binary, octal, hex to C++. what does your log file says?
FORSAKE ALL HOPE YE WHO ENTER HERE
Could you share a basic crashing scene with just a cube in it with the shaders applied and the mdl script use, please.
volume.mdl material
Test MDL.duf scene file
Noise Volume.dbm shader config
Interestingly on reloading (using a cube instead of my usual sphere), it got through a couple dozen iterations before crashing.
No crashes here. The input values are not what I was expecting, so I'm guessing you're going after something a little different. I'll wait for you and jag11 to sort out the crashing.
Tobor, the working theory right now is that the crash is Mac specific. If you're on Windows, you should be able to run what I posted with jag11's parameters and get something resembling his results shown above. Right now, the noise is only connected to the scattering coefficient. You might need to play around a bit to get something more snow-like.
You might also try working with the "Intermediate Volume" I posted, since the crash there is probably also Mac specific.
Didn't crashed either.
OK. Thanks. I assume you're on Windows?
I'll try applying the noise texture using straight MDL and see where that gets me.
W10-64.
I'm afraid my inexperience with shader bricks has me at a disadvantage here, so the only thing I can test is if it crashes -- and yes, I'm on Windows. I'm going to need to educate myself a little more about these brick things.
I'm guessing the MDL Callable entry is able to take values from the Perlin Noise Texture brick, and use those to pass to the surface, as that brick doesn't otherwise have an output. Have not seen this before, so something new every day! (I am guessing here. The output of the shader doesn't do anything on my system, even when I've placed the MDL in the roper paths, and added its own in the Directory Manager. Will keep at it...)
No, sorry, this was aimed at Esemwy's code example. Seems I accidentally deleted the quote block.
Corrected that.
Since the IrayUber seems to been build up from the MDL, I assume that in that case the DAZ Script EULA will be applied. As if I got that right from what has been posted in other threads in the forum, as long as you don't include any original geometry files and/or textures, or derivates of those, material/shader/whatever presets will fall under the Script EULA, and you're allowed to share them.
But now to something completely different:
If someone is interested, there is a pack of MDL examples available in the Material Definition Language examples for automotive thread at the NVIDIA Advanced Rendering Forum, including several for carfabric, carglass, artificial carleather (that's would be a new one), carmetal, carpaint, carplastic, carrubber, carwood, etc and textures. Thought to be used mainly for cars hence the directory namings, but one or the other could be useful elsewhere, too, though I guess.
I think I've reached some limit in my brain. Can anybody see what's going wrong here?
I hoped to get a noisy cube, but I got nothing.
Tobor, it sounds like you have the general idea. If you need more specific information, I posted a general tutorial a while back on working with MDL and Shader Mixer. It's here. Everything I've learned about Shader Mixer is from Carnite on Youtube.
If you rise the absorption coefficient to color(0.02) you'll see inside the cube but no noise. I think the scattering_coefficient ignores dynamic texture values I think iray uses the same scattering value for all volume.
On the first glance, I'd say you can't use a texture on the scattering_coefficent. It's the product of a color (as float) divided by a given distance.
scattering_coefficient: noise(noise_levels: noise_levels, size: size).tint
I can make out, that you have defined "noise_levels", "size" and "tint", but cant find "noise" anywhere. Ant the dot "." in front of "tint" doesn't belong there, too., I guess. It could also be, that the scattering coefficient will only work with a monochromatic color.
And I guess it can't make sense of the (noise_levels: noise_levels, size: size) part. They are already uniform, so it's IMO unneccessary to define them again. (noise_levels / size) would make more sense I guess. Any operation like multiplying, dividing, add or subtract.
This is my thought as well. The function for setting the coefficient is read just once, not for every pixel. Though it may not be physically-based, what if the texture plugs into the refraction node? That map is read for each pixel of the volume.
Esemwy, I'll check out those videos. You have to play her stuff five times to take it all in. She packs a LOT of information in there! Her tutorial on using D-formers was the one that finally got me over the logjam in using them.