Eyes (Glass Shaders)
CGHipster
Posts: 241
Hi, so I was messing around today with shaders and basically just tinkering away with the eyes mainly to play around with getting stronger environment reflections in the eyes as opposed to fixed eye reflections. I wanted ask what other tricks people are using to get more realistic eye reflections that are better affected by the environment lighting.
For these I used a clear glass shader on the reflection and messed around with glossiness and refraction etc, and the pupil I used shiny black plastic and played around again with surface settings. The results are not amazing by far but they aren't half bad and I am probably doing something that others have done before, so if anyone has good tips please share.
I duplicated the figure to have the eyes picking up light from different angles but I'm sure that is obvious.
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Might be a bit too much glossiness in the pupil. I, personally, mainly focus on the glossiness for the cornea and eye moisture.
Thanks, I actually never thought of the cornea or moisture. I will try what you have said.
How does making the pupil trasnparent impact things? I know in a real eye, there's a lense behind the iris/pupil which a daz eye doesn't have, but otherwise the pupil isn't actually a surface in a real eye.
If the 3D models had true lenses in their eyes (I think a few non Daz figures include 'em), would we want to use a mapped IOR to portray it? The eye's lens actually has a gradiant IOR between the edge and the middle, but none of the major shaders I've seen (including Iray Uber) even consider mapping the refractive index.
Details, details...!
Hi, for the pupil I didn't go with a transparency but what I did do was use a black shader (plastic/vinyl) on the pupil in the surfaces, what I was hoping was that I could get some objects from the scene reflecting in the eyes.
Probably easier to do with gimp than with try to get actual eye reflections in daz? Something like the photo below if it was even possible at all I wouldn't know, I'm still figuring things out in Daz.
Are you using 3DL or Iray?
There's glossiness on the pupils, too, as in real life the whole iris is covered by the cornea.
I noticed that since G3F/M the eye moisture is terribly dull in 3DL materials (just as the default setting of most skin diffuse colors is 50% only!). So in most cases I switch specular sharpness to 60% and specular sharpness2 to 70% (UberSurface/omHumanSurface).
Hi, I'm using Iray. Is, this something that Iray can do? Thanks in advance.
Iray, I haven't spent anytime yet with 3DL on account of my shameless hording of Iray shaders.... ;s
Thanks, so probably my messing with the reflection is the wrong approach? I never thought of the cornea.
Iray is a physically-based render engine, so you'd want your materials to mimic what is actually happening in a real eyeball.
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/eyescal.html
First... the pupil: Your pupil is literally a hole that allows light to pass through to the back of the eye, so if you're going for physically accurate, you'd want it to be pretty much transparent. The reason your pupil is black is because it's dark inside your eyes, lol. (And you know the "red-eye" you get sometimes in flash photography? That's because the flash manages to jump into your eyeball and reflect back off your retina before your iris has a chance to constrict and make your pupil smaller.) So, if you look at the texture for a character's eye, you'll see that the back of the eye is actually part of the texture -- I believe that texture would be displayed as part of the sclera surface.
The "pupil" material on a Daz figure would technically also encompass the fluid inside your eyes, so you could change your pupil material to mimic that -- and since the aqueous and vitreous humors of your eye are pretty much water, you could change the pupil's composition to water. Make the base color some shade of gray, change the refraction weight to 1 (100%), make the index of refraction 1.33 (that of water) and make sure it's set to "thin walled OFF."
Second... the eye moisture: Changing the glossy reflectivity does zero to eye moisture if you're using thin-walled water as your base. When you're using a transparent material like glass or water, Iray calculates all of those settings based on the index of refraction, the glossy layered weight, and the glossy roughness. The amount of reflection is actually calculated using the index of refraction because, in real life, that's how it works. As a general rule, if you increase the IOR, things look more reflective.
This is because (in fancy physics terms) Snell's Law, which calculates how much light bends when it changes speed as it moves from one medium to another. Without going into a lesson involving trig functions, suffice it to say that light which doesn't refract (bend) will instead reflect (bounce back.) If you want more reflection, boost the index of refraction. Make sure you keep eye moisture as "Thin Walled ON" or Iray will assume that everything contained inside the eye moisture surface is made of water -- making your eyeball the equivalent of a pool with nothing in it.
You can also play around with the "base thin film" setting. It's redundant, I suppose, adding a thin film of water over a thin-walled material made of water, but it might tweak the final results. You'll never get "perfect" accuracy, since the Daz figure's eyes lacks anatomy that your actual eye has, but it's pretty close!
Here are a few great tutorials on Iray settings and what they mean:
I've attached my quick experiments. I changed the pupil's setting to non-thin-walled water and adjusted the eye moisture as noted in my post. I've added my settings for the eye moisture as a reference. The background is an HDRI environment with speckles. (Part of this set: https://www.daz3d.com/iradiance-light-probe-hdr-lighting-for-iray-expansion-3)
Then I recommend the base Water Thin shader (that comes shipped with DS) on the eye moisture layer and cornea with a bump/norm that matches the veining in the sclera a la Project EYEray - Next Gen. Overall, I recommend Project EYEray - Next Gen for all your eye needs. It is a different UV for the eye surfaces, but it gives you finer control over elements like the limbal ring to give the eye as a whole a much more natural appearance.
Thank you for this! This is amazing information and I do appreciate your spending time on this.
Excellent, I bought a different version of this, and since this one is currently on sale I was (dare I say) "Eyeballing" it
I usually set pupil to flat black. Under the vast majority of cases it will produce a realistic looking result.
Or even easier, just set cutout opacity to 0, then your pupil is an actual hole.
8eos8: Except then you can get weird translucency issues. And I'm not sure you can easily set things up accurately enough for that to work. Making them practically Vantablack with cornea and moisture in front of it, IMO, works better more easily.
IMO!
Thank you everyone, ok I am going to run through and try each of these great suggestions.
Huh, I didn't know that... What kinds of translucency problems does it cause?
(Photos of Vantablack are pretty funny, it just looks like someone Photoshopped a big black blob in)
I was working on Genesis 8 eyes. This was a preliminary render I did before moving on. I still need to get rid of the halo around the iris :)
Click on image for full size.
Nice, I like the clarity of the eyes. In terms of realism, it is always the eyes that will make or break the render.