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Hello everyone, I Think it's time to step out of the dark and talk about Photorealism with Daz and Iray. Also apologies for digging the discussion back up, but this is pretty much worth it.
Like Many people here, i've tried to reach that Photorealism with characters inside Daz, but also like many people, always felt that something just never felt entirely "Right", and i could not put my finger on it, until recently that is when it finally became clear...
So as attachments, you will see where i come from, basicly borderlining against that "Photorealism" but never really quite getting it, even with advanced techniques employed like a Translucency Weight map applied and all that, it just would not budge in the way i was expecting, it does much better, but still is not there. (First Image)
I also constantly use well lit scenes and throw lights at it to see how things behave, and the first image looks good by all means, but even when she basicly is far from being a out-of-the-box character with proper techniques applied she still didn't quite break the veil of entering Photorealism.
Ladies and gents, i will reveal what the issue is, by simply using examples of what i experience and see in a render engine like octane.
First, you will need to understand that SSS and Absorption are VDF's (Volume Distribution Functions) that are different from your BSDF (Bidirectional Scattering Distribution Function).
Each Render engine basicly has SSS Nodes, but for example in octane, and in many other guides etc that explain how to do Skin, i always saw that the SSS Node have the ability to have a Albedo/Diffuse map plugged in, and that was just strange why the Daz Shaders basicly don't have mappable SSS or Absorption (Transmission as daz has called it) Colors. We have our first issue here.
The Second, lies in the fact with the Iray uber and PBR Skin shader equally, but the SSS and Absorption are the two ONLY settings that do NOT follow any tiling. this causes that basicly SSS and Absorption act as a complete 100% uniformal thing, which also results in weird behaviour, from errors like showing SSS in places where it first and foremost shoudn't even appear, to issues like Blowing up your character incorrectly with it's own volume when absorption is put way too high, trying to fix this issue is almost impossible, even with Translucency weighting which controls even things like SSS and Absorption, you would still get SSS and absorption in the wrong places. What a lot of us then do, is altering the absorption down to very low settings in an attempt to fix that issue, but suddenly, your character will also begin to look and feel like that Rubber/Plastic looking character i'm sure of everyone has noticed. Issue number 2.
The Solution: The very solution was before my eyes the entire time, and all it took to correct this issue, was giving the SSS Color and Absorption color the same treatment as with every other map, correctly giving them a Texture instance node and hooking them up to the tiling node, and also making sure the exposed setting is turned from non-mappable to a mappable one before reconnecting everything again.
Now, after that was done, i went ahead and applied my edited shader on my character, after properly texturing her up again, this is the result (Image 2)
Then went ahead, and just had to have both my images next to each other. (Image 3)
Basicly, it did not take long at all to see the difference it really made, but we went from strange behaving SSS and Absorption, to correct behaving SSS and Absorption, and it immediately made my character go from bordering on that close to photorealism to crossing over it showing what Iray actually should be rendering to begin with by default.
The Rest of the attached images are me further testing to make sure this entire thing actually is true, but i believe you will see for yourself. (Rest of the images)
The last one is even done using the default Ruins HDRI from daz, and when SSS and Absorption behave like it should... we can even see that Daz it's Default HDRI makes her look absolutely look much different.
I hope this will help poeple in their persue of reaching Photorealism with their characters, but any questions? feel free to ask them.
Melvin
@dbmelvin1993:
Thank you for your explaination.
I am having some trouble with your text. I know the SSS shader, but where is the absorbtion channel?
Is it availeble in both, the DAZ uber Iray and the DAZ PBR shaders?
Till now, when it comes to realism, the most convincing skin shaders by far are those from IsourceTextures at least for light skin tones.
It seems that achieving realism for darker skins is so much easier. Maybe that is the reason, that almost every skin shader for IRAY, is actually to dark.
This is just the basic Daz Uber shader
Different lighting here: https://www.daz3d.com/gallery/user/4822025778495488#image=1295663
Thank you for posting the link.
Sorry for suspecting you for trolling, because your picture looks so unbeliveble real.
Yes, well done. It looks amazing.
You give me too much credit. For skin, I have mostly taken advice from this thread from people like J Cade, MelissaGT, and Isadorekeeghan.
In the interest of summarising 60 pages of posts, some useful references:
only red eyes and white frame are edited in the post
A Maiden's Fault | Daz 3D
I did wanted to update the post already, as i think honestly that the effects show best in Emissive lightning and a HDRI.
But i cannot attach something to the post anymore and keeps infinitely uploading.
I followed most of these guides as well, but felt when you really begin using and testing in other settings, and properly throw light at it, that it begins to show most of the issues.
I hope this is allowed, but here are links:
https://ibb.co/tQH3ffZ (Head), Removed the hands and head since i came to the conclusion the light is just to insufficient to really show anything, the head render will explain enough.
Rather, i will just add 2 images of the settings so you also might get an solid idea.
Look at it and inspect closely.
Now, this is where the surprise may come.
First, i do make use of translucency weight mapping, but do not let that cloud your judgement.
Settings, and Translucency Weight Mapping: https://ibb.co/bgfPzTY
All my tests used very high translucency (0.95 to a full 1), and yes, many guides and people will suggest keeping the absorption or transmission low, in all of my tests you see, my transmission is equally as high as translucency between 0.95 and 1. Now this is where the difference also shows with emissive lightning.
here you can see the Transmission being on a full blown 1 and mapped: https://ibb.co/gPsnZKk (Also quick correction, because i suddenly noticed it, the detail tiling needs to be on 1 as i'm using the G9 Detail normals)
however, do not try this on the iray uber shader or the PBR Skin shader as it currently is, as too high translucency will quickly show how it affects the character overall, and a too high transmission will begin to have that Blown out effect that is also was demonstrated long ago.
Melvin
So Furthermore, J cade's Eye Moisture shader came to my attention, and just approached it with an open mind, taking in what he says are potential issues.
Looked at his shader, re-produced it by slightly altering and playing around with it myself, to come to the conclusion that it (for now) in this scenario was the SSS and Transmission, but i noticed SSS was set to a black (which should mean off), and transmission on a white. Now you also have 2 SSS Nodes, the one Iray Uber uses named Uber add Volume, and the PBR Skin Shader's Custom MDL SSS Node. After testing, neither's SSS and Absorption did anything favorable, so came to the decision that these should go.
Basicly my result (after alterations and no explanation prior).
https://ibb.co/8jmNv8Q
On my character:
https://ibb.co/ZzsM5cM (i'm aware of the very small poke-through there) (Edit 2: looked like poke-through, but it's not)
Still is uploading something infinitely so hence why, think i better re-log and clear the cache.
Melvin
Here i will show my exact thought process, and also the changed and their effect.
First lets establish the look J Cade has shown. Every Color map is unmapped, as well as the Translucency Weight here:
https://ibb.co/sKQBp8H - For Me, It's a White Jello Monster. in any situation, the settings i also have are unrealistic for the Default Shaders and would give you this said result. Let's Look what happens now.
This is When Mappable Transmission means:
https://ibb.co/M1LkWCY - The Very White Jello Monster now has dissapeared, and suddenly the Absorption is forced to the Ears, Lips, and nose, and around the eyes slightly, the rest of her head now is also dramaticly less a Jello monster Suddenly.
When SSS is Mapped - This is the least noticeable when Absorption is already mapped too:
https://ibb.co/SNkPxTk
Then, Still looks like a Jello Monster, but let's fix that with a Translucency Weight Map to give her skin "Thickness":
https://ibb.co/Gd7fgSY - Now we got entirely rid of the Jello Monster issue, and we have not touched our values at all.
End Result when the Translucency color and diffuse are added back in:
https://ibb.co/k1NYytW
Alternative Setup - Using the Translucency Weight map into the Transmission and SSS Channels using 2 Contemplary colors instead:
https://ibb.co/hKHdZcp
And Finally, What was Changed from a Shader Stand-point? This:
https://ibb.co/n7j3m4p
Apologies but i still get the Infinite Uploading issue, so i can't directly post any .duf preset, but i can show how to do it, and what effects it has.
What does this do? Simple, it fixes the SSS Problems of the Jello Monster, as well as fixing the issue where a character has the coincidences of lowering the transmission as a attempt to get rid of the Jello monster effect and now equalizes the settings with what would be possible in advanced engines like Octane, V Ray, etc etc...
This also enabled you that you can push the settings way further to even the level of interpreting how real skin behaves, up to the limit of what Iray statistically can render correctly.
Melvin
Melvin,
Great work and keep exploring, it's a long twisted road when it comes to photoralism. But the idea that Daz's Iray is inferior to others is nonsense except for speed, when it comes to actualy rendering it's just as good. I went down that rabit hole too beliving the fault must be with daz's renders when looking at stuff made with other engines, but that isn't it. The real issue as you have already been exploring is the shaders and lighting setup. Instead of using point, or sphere or plane emmisive lighting try a curved backdrop that will help scatter and distribute the lighting. I have also pretty much dumped normal maps for displacement maps. it can't be stressed enough, that the quality of ones textures (including specular) and removing Daz's texture compression is paramount. I am currently reverse when it comes to translucent settings, going for more .2-.3.
I have read through all those posts about adjusting sss and translucent to get ears so transparent and such and in the end it just screws up the rest of the skin. But mapping as you have brought up may help.
Hi Charles,
Iray is very capable, but it's certianly not out there with the rest, and since we are also rapidly moving ahead in technology (RTX Real-time and even beginning to play around with the idea of Path-Tracing in Real-time) Iray is just falling more and more behind.
The Problem indeed does not come from Iray though as you mentioned, but mainly lies in the fact of the Shaders, but also in the maps and settings.
If and how you will approach the Translucency weight mapping will be up to you, but it's a very delicate map that needs tweaking and adjustment, but also testing.
It always felt to me that the characters felt just indifferent from their environment, no matter what i did, they just didn't feel "Right". Shader wise again.
When you do want to reach Photorealism, then (In the PBR Skin Shader) be prepared to make that correction with SSS, and get ready, because you will likely only get to experience what the True potential of that shader is once you really begin to utilize every setting, but also no longer stick to just 4-5 maps, in my finished characters, she is now using 14 maps per Body part, utilizing the PBR Skin Shader to it's fullest potential.
Thanks for the reply, and i always have.
Melvin
Not sure youre using PBR Skin to its full potential since you are not using Dual Lobe Spec much (your weighting is 0.04) and no proper spec map.
Proof to me that settings are working is when I see an image that looks good.
I'm still using a cusotmized Uber which is also a PBR and works great.
I also use the Uber Iray shader for skin also.
It doesnt have the microdetail maps options, but with good maps it's not totally necessary. 8.1 and Gen 9 have good UV layout for all UDIMs so 4K is usually fine for getting enough detail. Maybe with extreme closeup it would be good to have microdetails, or otherwise use 8K maps. These details can also be baked into HD morph or Displacement map rather than using a Normal map, so again not totally necessary.
Dual Lobe Specular should provide some variation to get the appearance of microfacet detail in the specular property, so can give illusion of more detail
I do prefer the DLS, it sometimes can be frustrating like if not done right you will get seems that are not always obvious that's where it's coming from.
You can do 8k or 16k on whatever model you want, this isn't unique to g9, it's just the file sizes are so insane and most artist believe 4k is "good enough". But I've got some 8ks for g8 that are amazing. I also made my own 8k microskin which can be used on the thin film channel or top coat or wherever. Only instead of having a small map that tiles it was done via wrapping in Susbstance very large textures for the main body skin maps...so VRAM overhead on those can be tight.
but also it depends on what one is doing, if you're doing portrait head shots then you definantly want those higher detailed maps, but body shots ehh, you can get by fine with 4k. But this doesn't mean squat if you have left your texture compression to default.
Something else I'm not sure has really been addressed here much regarding "photorealism" is what camera settings you are using. The standard camera is like 65mm focal length and this is not common. This does usually feel out the viewport nicely, it's not what we are use to seeing from "photos".
I also have some 8k textures for every single channel for G8.1 and G9 that i custom made, but i never use them as they dont seem to be necessary.
Are we supposed to be changing this from the default 512-1024? What does this do? I never once changed this setting.
On the topic of 4k maps vs 8k, attached is a G8.1M using 4K displacement maps. (If character looks familiar to anyone as a G9 character, originally I made this character for G8.1 but then I remade the final version of it for G9). The skin is just using one of my G8.1 character skins for Iray Uber shader, with the shader settings I developed using the methods described above in a previous post.
There is room for improvement, so 8K displacement probably would give a much better result, as would I think increasing subd for the finer detail as getting details from displacement map can be really difficult. But for medium closeup 4k is usually fine.
The character does also have some HD morphs dialled in, mainly just HD expressions in some of the pictures.
Note: these images have pretty low iteration count as were just test images.
Yes, when Daz hands off your textures to your video GPU or IRray it compresses them based on that, I have mine set to medium=6000 and high=10000
https://www.daz3d.com/forums/discussion/465471/texture-compression-in-advanced-render-settings#:~:text=Every texture image with a resolution above High,only textures above that resolution will get compression.
Thi s is very good!
Yes I've pretty much dumped normal maps for displacements in most cases. You will probably want to crank that dubd up to like 11
Displacement's been a lot of fun lately once I grocked how it worked, overlooked it for years. But doing things like making wrinkles in clothes and sheets or adding skin details one ccan't without being a PA for actual morphs is pretty cool.
Well, With a proper Specular map, i would mean this: https://ibb.co/WB6SKgy
My Settings have changed since, and been playing around with a few things. I came to the conclusion that it is the Specular Weight channel that causes those sometimes Harsh black shadowing in Areas, so i just put in a Simple Perfectly Mid Toned Grey color in it now, with a value of 0.94, however my reflection remains untouched and stays on 0.04, where the shown map now sits.
Turns out a Proper RGB specular carries much more data in terms of Specularity, with each color representing something else as opposed to just a black/white one which tells Iray on or off, or in this instance non-specular or specular.
My aim, which has worked, is to create this effect: https://ibb.co/nbfcS9p - A Very Angular visible Specular Effect. Here it is with Simulating the effect of a Windows with light and her right being shadowed: https://ibb.co/3BVYNVb
And Here is a more Completed look at this: https://ibb.co/p4tp3sC - quickly rendered yesterday. All of this just begins to look much more pleasing and interesting to my eyes.
---
My Approach to Photorealism and skin has changed over time, the more familiar i became with Daz and it's settings over the Years, the more i began playing around. Took the time to learn a bit about the shader mixer as well, although it wasn't an easy task as Daz Nor anything else explains MDL, except for Substance Designer that has two video's explaining how to begin with MDL, explaining and showing how you can make a Metallic Shader to get the process going and familiarizing yourself with how things works, this translates very well over to the Shader Mixer in Daz itself, only the layout etc is different. My Story basicly is that i've messed around with the shader mixer, and already succeeded in for example, creating a Skin Shader that has the Make-up layer as the PBR Skin Shader has, but even added a Sheen effect on it.
Digs around for a few... - https://ibb.co/FHn88s0 - And there we go, about the size you'd be looking at from a shader standpoint inside the Daz Shader Mixer, that is from around end 2022 when i did this, and was all in practice learning more about the MDL language and how to use it properly.
Some Results from that Massive thing (And all before knowing the SSS Stuff): https://ibb.co/2cC8g2q - https://ibb.co/kDQQrmh (Lipstick without Sheen) - https://ibb.co/KymmL7x (same, But Lipstick With Sheen)
This was just a fun Learning experience, and nothing really like end-product stuff.
---
Now, In Terms of SSS Stuff... I did a simple test here too, and wondered if you can actually use more then 1 SSS and Transmission Color, but on the other hand, also looking at how the SSS Behaves now on a Sphere for example.
Setup - https://ibb.co/Xt4PzWL - very simple, Driving a Iray Uber Specular Base Through 2 of the Custom Volume MDL's that the PBR Skin Shader has, and bringing that together in a mix material node, also again, hooking up the SSS and Transmission Colors of each through the Tiler, making them Mappable.
Results: https://ibb.co/Pr8hyfL - Left is with the Secondary SSS and Transmission on a full White, Right is when we introduce a Yellow-ish color, and a Darker Yellow-ish color.
---
Why do i not look at Daz Tutorials? Simple, it's because i don't get enough info from them anymore, or just changing sliders is for the answer i need anymore.
https://sciendo.com/downloadpdf/journals/sjdv/2/4/article-p131.xml - is a document i found, and it actually has quite a lot of useful info, when you read through it, or basicly it's an example of when Science and Art or 3D Meet.
This was a long post, so i hope this helps people, but also shows a bit more of my background and what i've all done already myself.
Melvin
Melvin,
Very cool your anaysis and probing of the deeper workings on the Shader system and PBR technology. However all I can say is that all the theory may not be as good as just faking it :)
Photorealism is not just how good the skin render is, but composition, character detail, expression, hair, lighting everything. If anything is off you dip below the uncanny valley.
When it comes to the SSS I would rather just have great skin textures to start with and control specular.
Hi Charles,
I know, and each has their own style. My characters skin went through Colm jackson's skin detailer to add imperfections etc. And this is why I said earlier Iray is not up there with the rest. :)
Once you had a go with octane render for example, you will known what i talk about. Octane is much better with handling light, materials, etc and it just feels worlds apart from Iray. Getting 100 Percent close to how everything is to the real-world is not possible, but we can only try to get as close as possible, or as close it will let us. ;)
Melvin
I'd like to add something else to all this.
The problem in IRAY cannot just be the skin shaders, but also the way light works in DS IRAY.
My observation is, that with one HDRI plus one light source, you can get a quite realistic looking scene, but the more light sources you are adding to the scene, the more it looks like a CG scene.
So I guess, that some sort of inaccuracy in lights (lights and mesh lights) are accumulating and ruining realism.
Indeed, you are beginning to understand it.
Iray is a Biased Raytracing Render engine, as opposed to Octane for example, Octane is an Unbiased Pathtracing render engine, and while it also has it's own problems, Path tracers handle light differently etc.
Ray tracing, and what Iray does is this: https://miro.medium.com/v2/resize:fit:1400/1*sJWf5cb6OL0mQsPhx9u0gg.png
From your POV, it will calculate where light and shadow fall, by looking where the lights in the scene are, and thus determine from that where shadow is etc. Light have their own power, but because lights also have a linear path, this explains why for example lights don't feel as strong or good in Iray, even if emissive lights are the superior way of lighting things in Iray, they lack a "Real" sense of power, in a logical sense, Iray is only "Guessing" at best how things should be.
One thing you can do, is trying to render a light at like real world Wattage and it's accomendating luminance level, and you will notice how dim that can still look in Iray.
Path tracing on the other hand, no longer looks at lights and objects in your scene, and light sources also shoot out many rays, in essence, Path Tracing is a freed form of raytracing, and calculates it's entire scene by continueing to shoot out rays from your POV and Light sources until it's completely figured out. More over, because lights do shoot out their own rays into the scene, doing the same Wattage and luminance test will show you that the light itself will actually get much closer to it's actually real power outage to that of the real world.
https://d3kjluh73b9h9o.cloudfront.net/original/4X/d/6/0/d60a88a18278e9102da6cf4bfb9b6e7a8b00e3e9.jpeg - is a perfect example, but in the path traced preview, you see light is brighter, and also feels more lively because it can reach area's that ray tracing or Iray can't reach.It's because light itself also shoots out it's own rays in Path Tracing.
I really learned the difference between the two when i played Cyberpunk 2077, which has Raytracing in Medium, High, Ultra and Psycho settings, and as of late, implemented their Tech Preview of what the game would look like with their "Overdrive" setting. (Which is Path Tracing in a game).
Nvidia has explained Path Tracing as "Full Raytracing" as it accounts for everything, direct and indirect lighting and affects everything in a scene. whereas Raytracing is only Direct lightning and limited to Global Illumination, shadows and Reflection.
Hope that explains it more in-depth.
Mello
Not to relitigate a conversation from earlier in this thread, but I thought Iray was unbiased, at least it is touted to be. Maybe nominally it is unbiased but mathematically biased?
With Biased, it is said that a Render Engine Can get quite close to Realism, but due to it's limitation you will always see that it is CGI, no matter how hard you try. That's the feeling i get with Iray.
Even now when i use Real scientific values on my character, in Iray it still feels CGI, even though it has made a very dramatic improvement solving the issues i typically run into with Iray, you can still tell it's CGI because of the way Iray calculates and renders it's stuff.
And with typical issues, i mean this:
https://ibb.co/pRLJzQP - the type or wrong that gives you the indication there's just something off.
The SSS From her ears is way too strongly prominent, and here it feels like most of the light is being bounced off her skin rather then being absorped causing it to like "Bleed" on her skin in an ugly manner. the HDRI is overexposed though.
https://ibb.co/Hg9gjPL - same example, but with a non-exposed HDRI. Still the same issues, but the SSS there is very prominantly visible still on her ear.
What i always began to do, is When something feels off on my PC Screen, i take my phone, which has a lesser screen as opposed to my PC Screen, and more often then not, when i'm right about that feeling, my Phone really shows what's wrong.
The Last image for example on my phone screen, made it very clear that there is a orange-ish color going through that ENTIRE Characer, giving it the feel like she's a very dim orange light bulb.
Final Edit: This is why Blender with cycles & Eevee became a industry standard as well, because it's such a powerful tool to create things with, but also because Cycles is an unbiased render engine that is on par with Octane, they are both able to Render Unbiased "Physically correct", and why Daz and Iray slack behind is because Daz and Iray Render Biased "Physically based" making a guess and giving you an "Idea" of how things look like in real-life, but it stays by that "Idea".
Melvin
Iray is, in Photoreal mode, an unbiased path tracer (it also has other modes which are not fully unbiased). The sahder code, or coursse, makes a difference - and soemthing that isn't a fully soild model with internal structure is not going to match reality, regardless of the engine or shader.
I'm not sure where you get the idea that Iray is a Path tracer, Richard, but for me, Iray is not even remotely close to being a Path Tracer.
https://blog.irayrender.com/post/142742319456/is-iray-an-unbiased-renderer-can-it-be-used-to - Also this, Lilweep would actually be correct, but Iray " is not unbiased in the strict mathematical sense".
Just from how it functions?
"To generate realistic and predictive imagery, the rendering core of Iray uses light transport simulation based on a subset of bidirectional path tracing"
https://arxiv.org/pdf/1705.01263.pdf
All render engines are approximations of what's happening in reality. Most people would describe Iray as being unbiased and brute force.
- Greg
Like, i think that document though shows exactly what Iray does when you actually don't use Daz. since, i wish, my guy, but i have not even seen any Daz studio render coming even remotely close to that Mercedes render as seen in the document.
And the "Brute Force" there would for me mean the biased stuff, since i can't imagine something as unbiased but brute forcing it.
Melvin