OTOY Forums

Hi I'm currently working on the eyes of a character but I got stuck trying to make the little wetness layer that goes between the eye and eyelid to make it blend a bit better.
Whatever I try to do the little tear line always turns out too dark giving me a weird result that I can't use.
Even when I set the opacity in the specular material all the way too 0 the black shadow of the object still remains.
this is what I am trying to achieve (where it says tear line):
http://www.therookies.co/wp-content/upl ... wal-01.png

the most common technique to achieve this is to do something like this:
https://us.v-cdn.net/5021068/uploads/ed ... 9glk6y.jpg
https://i.pinimg.com/originals/44/ba/de ... 6b69b9.jpg

however whatever I try it doesn't work out the way I want it to.

At this moment I have tried a couple of things:
-have the tear line as full geo
-have the tear line as a plane
-used gloss material and played with the opacity but that just removes the specular I need
-used specular material but that turns out too dark
-tried playing with the IOR in spec material to no avail

I'm not sure what to do next but the only thing I can come up with is to boolean that tear line with the outside of the eye to make sure they don't fight.
If someone has an idea on how to fix this please let me know!

Hi,
which kernel are you using?
Please, have a look at these old but very interesting discussions:
viewtopic.php?f=6&t=37439&hilit=eye
viewtopic.php?f=6&t=40671&hilit=eye#p190859
ciao Beppe

Hi Beppe!
Thanks for checking in.
I tried using both PMC and path tracing but it makes very little difference.
There's images attached that show the difference + an image of how my specular shader is set up at the moment, maybe I'm doing it completely wrong for all I know.

I had checked out those two posts and the post from Rikk The Gaijin shows it should be possible as he absolutely nails it: download/file.php?id=33472&mode=view

I'm wondering what I am doing wrong as I can't figure it out, I hope you have a better understanding.
Kind regards,
J

Just did a small test rendering the different meshes I created for the tear line with just the eye and nothing else.
I think the plane works best for what I'm trying to achieve but as soon as I introduce the head again I get the same weird results.

Did another small test to see what could be causing the issue.
This time I used the plane geo and checked it with just the eyeball, then just the face and then all of them combined.
I'm starting to have the feelin that the issue is caused from the tearline being too round and reflecting a little like chrome would resulting in these weird heavy shaded edges.

I will keep updating this thread as I go but if anyone has some more information on what it could be please don't hesitate to let me know!

so, small update
I managed to get rid of the black chrome like edges, it was caused by the ray epsilon value.
However the spec material still darkens the geo behind it weirdly so I'm still stuck...
I tried changing the shape of the geo but it doesnt do much, it always looks about the same kind of dark.

I hope someone might have an idea what this could be or how to fix/get around it.
Cheers!

Hi,
I would try to enable the Fake shadow in the Specular material, use an HDRI for lighting, and slightly overlap the geometry.
Note that you don’t have white behind your lacrima, so the effect is different from the Rikk reference.
ciao Beppe

Hi Beppe,
Thanks for the input!
I've set up and HDRI and tried enabling the Fake shadow parameter in the spec material but it makes very little difference.
I also think that the white behind the tear line is not the problem.
As you can see in the comparison image the side where I hide the face has the tear line rendering fine without darkening what is behind it, but as soon as the face is included the tear line darkens.

Cheers,
J