OTOY Forums

Tugpsx wrote:t_3 Now these look fantastic. We would all love to learn how you got these. Tutorial

the bottom one is a foto;
mentioning this just in case

rather than giving a tutorial, i'm going to add the mats to the plugin; as presets, or in a completely set up demo scene - once they are done.

the full version is here btw: http://render.otoy.com/forum/viewtopic.php?f=5&t=38674
...

Just want to say thanks again for the help and sharing your solutions. Sharing an image I did the other day

t_3 wrote:my problem with this is, that the cornea is a planar surface, so using a specular mat with a somwhat real ior will create unnatural distortions to the underlying iris mat. lowering ior and with low enough reflection i either loose the pretty sharp reflectivity that a real eye surface show, or it darkens the iris too much.

I gathered as much from you old posts on the subject. Would it be an idea to make a better eye model and geo-graft it (once that works)? It looks like it would be trivial to add some volume to the key components (lens, sclera, cornea). They could even be remapped to a better UV map for the critical components, and the morph controls should still work.

What settings are you guys using for opacity? My eyes end up with rather dull reflections or weird alien reflective eyes

DrHemulen wrote:What settings are you guys using for opacity? My eyes end up with rather dull reflections or weird alien reflective eyes

i'd say: better geometry yes, maybe even uv-remapping is already sufficient - most probably.

i have also tested a modified eysurface geometry with real thickness including the lens shape, to simulate the water film, but the outcome is not worth it; octane doesn't work very well with material zones/boundaries that are only fractions of millimeters away.

on the other hand you can't go with just iris/pupil/sclera (as i thought a while back) since these will never create correct reflections.

i think the most useful recipe in terms of minimum needed modifications vs. result is sclera + cornea (like above), ideally using the exact same material; this also covers the fact that reflections are created on the outermost shell of a real eye.

what the example above is currently missing is the wet look that a real eye naturally has; but when working on the teeth material, i got real close (imo), by using a specular + sss & glossy + thinfilm material mix. imo it should be possible to use that for an eye material also.

so the only modification needed would be a different uv-set for the cornea in order to have it take the high res pupil texture instead of the full sclera (with only a low res iris).

drawback = no more control of pupil dilation - the benefit is compatibility with any existing eye texture, plus perfect reflections...

Great, thanks for the explanation. I think I'll just wait for your default materials and stop wasting so much time on this for now

DrHemulen wrote:Great, thanks for the explanation. I think I'll just wait for your default materials and stop wasting so much time on this for now

in order to get in this direction already now, i'd try a simple glossy mat for these two surfaces, and play with the roughness value (pretty low) and specular/bump maps as usual. i too tend to tinker with rather complex solutions, but often enough more simple approaches do also well enough; if you don't do super close-ups or high res imagery, the lower res pupil also may not hurt that much.

btw, any hq mat comes also with a prize = performance decrease. the image i have posted to the gallery did render only 2.5ms/sec on two titans = 6hrs for the full res version - with pt; pmc even less, but the pt result was interestingly better anyway (in terms of noise vs. time)...

Yeah, if all else fails I can just use the DAZ cheat with the eyereflection layer...
Why do you need a specular map? I'd assume the entire surface should just be as reflective as possible?

DrHemulen wrote:Yeah, if all else fails I can just use the DAZ cheat with the eyereflection layer...

never

DrHemulen wrote:Why do you need a specular map? I'd assume the entire surface should just be as reflective as possible?

you are right - usually there aren't spec maps for the eyes anyway...

hmmm not too shabby.

Eye reflection :-
Specular material
reflection 1
roughness 0
index 1.45

Cornea :-
Octane database material

iris, pupils and sclera :-
Glossy material
reflection 1
roughness 0.0632
index 1.33 (water)

Lit by two large meshlights, PMC render kernal.

I did some testing myself and after trying many things (including creating my own custom eye objects with adjusted mappings and so on) I basically started using a setup where:

Iris and pupil are default diffuse materials converted by the plugin. EyeSurface/reflection surfaces are disabled.

Sclera is glossy:
With Diffuse and Bump maps applied.
Spec 0.3
Roughness 0.05
IOR 1

Cornea is Specular:
Reflection 1
Transmission 1
IOR 1.38
Filmwidth 1
Film IOR 1.33
Roughness 0

Results are relatively OK

EDIT:
I included a closeup of the eye rendered using the same material setup as listed above from a different scene. The reflections are there but on the Cornea they are still quite dull.