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#51, Then I often have felt difficultiy to convert iray refraction (thin wall on) of eye mats , but today I tried one way which I planed but did not test. without mix with transparent shader.
compare these 2 pic please. both use same HDRI, and same cycles mat setting for all eyes mat. every render setting is perfectly same . which image you think better or more reasonable for eye reflection,and refralciton?
pic1 (without solidfy modifier)
pic2 (with solidfy modifier only about "eye moisture sphere" vertices)
At first, about genesis3 (and maybe genesis2 have same eyereflection parts) eye reflection part geometry is mostly closed sphere without any thickness. (so it is same as primitive sphere)
And "Eyemositure" is reflection (and refraction) part for genesis3female eye. Then Daz iray mat often use "reflaction with (thin wall "on") for the surface.
I understood why iray refraction (thin wall ON option) will not be converted correctly for principled bsdf transmisison. I had felt it may difficult to achieve it, with principled bsdf transmisison only. Then I suggested to mix transparent shader to reduce problems. (if you need) . Of course it is not best way, because if I mix transparent shader with transmission, it may reduce wrong refraction problem. But it will reduce reflection (specular glossy) effect too. we often need clear specular reflection about eye moistyre mat. (to show env image etc). So I hope to use cycles principled bsdf "transmission" as iray "refraction (thin wall)" if it can work.
When we set "thin wall = on" iray just treat closed surface thickness as almost zero (really thin wall maybe micro meters?). then it can show correct refraction for eye mositure with keep reflection. .
On the other hands, Cycles principled bsdf transmission, (and cycles refraction shader) treat closed sphere as "full thickness sphere" about refraction. If we set refraction (or principled transmission) for closed sphere, it work as "thick magnifying glass" with sphre radius. it is pic1 (without solidfy modifier)
It show pupil becom very large, and deep refraction effect with ior. To correct it perfeclty actually we need to change geometry of eye moisture (mainly closed sphere part mesh), not shader.
There are 2 ways, 1 is destructive. simply apply normal thickness for the eyemoisture sphere surface. (about 0.01 scale, may need 0.0003 etc as you like, with keep good offset) it is most reliable, and may not cause setting problem or flip UV things.
I hope to keep original mesh, for morph import, then duplicate original full body mesh, remove other part, and only remain eyemositure sphere, and apply thickness manually. then use mask modifier, or apply transparent shader for original mesh eye mositure, but use transmiison (principled bsdf) for, new duplicate eyemositure. it work well.
2 is non desructive, use solidfy modifier. the merit is it not chagne actuall vertex count, then import morphs still work. but about this case, I needed to set up carefully, I saw some strange normal problem. (I serch google, and there were some reports with solidfy modifier and normal problem, but I can not find clear answer, it seems depend on each case,,)
Above pic, I apply solidfy modifier, only about moisture sphere part. with vertex group. then remove doulbe uv, about I edited parts. material view seems show wrong normal about non solidfy mesh parts, (it show invert normal, though I have not apply thickness for other skin parts). but when render it ,I have no problem.
And this is my setting of solidfy modifier, for the selected parts (I set new vertex group for the eyemoisture sphere)
and you can see, I actually only use principled bsdf transmission (weight should be 1), then it keep real reflection, with refraction, as same as iray refraction (thin wall ON) setting.
and I feel it reduce high noize problem about eye refrection. (deep thick refraction with reflection often cause issue for noize I think, it more strong when we try in room render, with many light setting)
So I may need more test, but I feel, at least about eye mat (for g3 etc) this procedure work well, and will be auto applied by plug in . But To suggest this as request, I need more test (I need to find best setting and stable procedure, because I saw some flipping UV with solidfy modifier and needed to correct it, to get this render)
Anyway, I hope thomas check this topic. you may not hope to mix transparent shader for convert iray refraction , I believe. and it may be useful for those who have seen same problem, but not hope to mix with perfect transparent shader for eye mositure part. (or reflection sphere of eye)