I'm having some trouble with this, and to fully explain I really ought to post an awful lot of screen shots; however I don't really want to expose other people's node set-ups, either to ridicule or copyright infringement.

I'll be experimenting further myself later on today, but in the meantime I thought this must be something that others have done and there may be some general pointers.

First picture: the character with the glasses made invisible. This is the materials from PDesign's Priscilla for V4, rendered in Poser 7. I should point out straight away that I've tried other commercial V4 materials with the same outcome, but not as yet something simpler. I've also tried simplifying the eye materials by removing nodes other than image maps, again the problem remains. One of the barriers I've encountered is that I don't really understand what V4's eye materials are doing, so I'm not sure where to start.

Second picture: with her glasses visible, showing the problem.

This is the lens material for the glasses. I'm assuming this isn't fundamentally flawed since her skin etc. renders all right behind the lenses.

And these are my render settings. I've finished posting images for now - any comments at this stage?

might be a silly thought, but what happens if you flip the image map of the ceiling from uv to vu? it seems like the reflection has reversed itself, so maybe flipping the image will rectify it

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What's odd though is it's just her eyeballs... her eyelashes are okay?

Weird one

My guess would be that the corneas are set up using ray traced refraction - increasing the number of ray bounces should make the eye ball visible then.

what poser version are you using?  If using poser 9/pp2012, you could set up a more accurate glass shader for the lenses of the glasses.  Using fesnel blend and transparency.

 

http://www.renderosity.com/mod/gallery/index.php?image_id=2338744&user_id=478758&np&np

Are you sure you want to use the fresnel node? I never understood what it does (in poser 8). I would have *assumed* that it does something like refraction (and from your node setup you might have thought that, too), but it looks more like it rotates all normals by 90 degrees of the objects behind it (in the image left: a ball behind the fresnel node with ior 1). You could try the refract node instead, or, if you insist on using fresnel, explain what it does :-)

Just to add: Are your glasses double sided or single sided? That does make a difference with refraction and/or fresnel in particular.

Just add more bounces... 3 will do.

-How can you improve things when you don't make mistakes?

IDL dosen't work properly with a refraction node; it sees it as opaque. I don't know about Fresnel...

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if the gasses shader seems to be the problem you could look for BBs thin glass shader as an option

Thanks for all the comments, and sorry for my extended absence from this thread. To cut a long story short, the culprit was that Fresnel material. It has its faults, but I've got away with it in long shots before - and not so long, my avatar's glasses are made the same way. He's based on Michael 2. I'm sure I've also used the same material on generation 3 figures' glasses without trouble. There's something about V4's eyes that seems to bring the problem about, but I haven't tracked down what it is yet.

I used a material which I've called "BB's 5 node Fresnel" - I think I got it from the RDNA forum - and that works fine.

I'll post back when I know more. I have a rather ghoulish test set-up consisting of a single V4 eyeball sitting in front of a sheet of glass. :) 

one thing that was causing problems with some eye shaders for v4 was the extra layer that it has.  Both an eye surface and a cornea.  Now these problems that I recall came into play in discussions about sss eye shaders and one solution was just to make one or the other completely invisible.   Just a thought

Yes indeed. My father was an optician, so I'm reasonably familiar with the parts of the eye, and I don't recall EyeSurface ever coming up in conversation. :) I suppose it's supposed to correspond to the tear film.

Time for some tests. Anyone who doesn't like dissected eyeballs should probably leave the thread now.

I made a version of V4's rEye with the cornea and eye surface materials cut away, so you can see what's placed where.

Englishbob, thanks for that picture. It will help those of us struggling to figure out what all those mat-zones are for.

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Exactly - I couldn't figure it out myself, so I thought I'd put it here for anyone who cares to do a search in the future.

Now to the problem - it's apparently caused when a surface with a transparent material is very close to another surface, and you look at them through a simple Fresnel material. This is Poser 7, by the way, and may not apply in later versions - if anyone can confirm, deny or clarify, please post.

Here's my dissected eyeball with simple materials applied, and the Cornea and EyeSurface at 80-90% transparency. I've annotated four areas, and you can see that where there is a transparent EyeSurface seen through the simple Fresnel material, the problem occurs.

You'll see that the sclera is affected, but the iris is not; that's because the EyeSurface is close to the sclera but further from the iris. 

Note 1 indicates where a similar problem exists, caused by the transparent cornea getting close to the iris.

The solution is to use a more complex material for the "lens". Bagginsbill's Five node Fresnel worked for me, and I imagine that later versions of Poser have other options such as the Fresnel blend mentioned earlier. Incidentally, increasing the raytrace bounces doesn't help. 

Attached Link: http://forum.runtimedna.com/showthread.php?25885-The-Fresnel-Effect-Glass-Paint-Plastic-and-Metal&p=266081&viewfull=1#post266081

The five node Fresnel is at the link, for reference.

i found a workaround on the GND4.2 glasses for a similar issue. i wanted refractions on the glass so that there would be lens distortions, but refractions + shadows enabled ended up with really dark splotches from the glass. so i had to separate off the glass into its own separate object so that i could turn off shadows for it. so technically the glass itself doesn't cast a faint shadow (but the frame does), but IMO its better than the alternative - which is just doing the glass with transparency. you can see the lens distortion in the main promos renders for GND4 and the bikini.

Bagginsbill has a set of eyes on his site.  I recall that they are mapped for Antonia textures... 

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Quote - ... refractions + shadows enabled ended up with really dark splotches from the glass. so i had to separate off the glass into its own separate object so that i could turn off shadows for it.

Yes, this one of the other problems with the simple Fresnel based material. It casts shadows. The glasses in my scene are a figure, not a prop as most glasses are, and the lenses are a separate actor so that shadows can be turned off for them and retained for the frame. That's an acceptable workaround most of the time, but with tinted lenses, light which is supposed to be shining through them doesn't cast a tinted shadow - there is no shadow. The character is lit by a desk lamp in front of her, and in one shot I had to fake the shadow of her lenses in postwork.

When I'm using prop glasses, I've had to do the same thing: separate them into two props, lenses / everything else so I can turn off shadows. My avatar's glasses are made like that.

I think it's time to move away from that material. I only persisted in using it through inertia. There's no penalty in using something more complex, and plenty to gain.

Hi,

 

Here's what you're looking for ( crappy render ).

 

For closer props or parts or for a simple glass, i never use refraction, only reflection.

 

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This one is the older shader i use for glass or cornea

 

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Now the new ( bb shader )

 

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And for the lens

 

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Merci beaucoup, Anthanasius. Those should be useful for people who can use Fresnel_Blend.