[Lars Magnusson]

Ok, I've created pretty realistic Eyes before, but then it wasn't exactly correct in size and dimensions.
And since that is pretty important in Maxwell I decided to redo it.
Spent a lot of time at different wiki's and google searching to get it as correct as possible.

Used trueSpace7.61beta8 for the eye design. Tricky since tS isn't the optimal tool for small objects.
Constantly had to scale it up to be able to actually work. ( The orthogonal views in tS can't zoom in close enough)

( And FINALLY Flickr has a solution for BBcode to make it easier to post in forums! )

Eye Render Test by LarsMagnusson, on Flickr

Slightly underexposed, but that doesn't matter for the test purpose.

This is a test to decide what approach I should choose for Eye design.
(Overlaid the model mesh in photoshop to make shapes easier to understand)

Left side:
Traditional Render trick. Modelling the Iris as a bowl to catch light. Basically simulating Caustic effects.
Then in Maxwell turning off "Global Illumination" for the transparant/refractive exterior volume.
As you can see in the top left, it disables shadow casting and caustic effects. Renders very fast!

Right Side:
More realistic approach. Human Iris is rather flat, and it's the caustic effect that lights the right side of the iris.
This method of course takes longer because of the caustics.
( the right "eye" is still noisy because I only had let it render for 5-10 minutes)

So I think I'll stick to the old cheat on the left side...

Now I have to UV map it and create textures/bumps etc.
( my previous eye design only used planar front mapping...did look weird in renders like this since the back of the eye had an iris too )

[Aniki]

This method of course takes longer because of the caustics.

I doubt that you see caustics through the dielectrics there.

http://maxwellrender.com/forum/viewtopi ... 97&t=32534


cheers

Aniki

[Lars Magnusson]

Hm, am I using incorrect terminology? I used the word caustic as a description of how the light goes through the IOR 1.34 external body and in the middle right eye lights the inner "white" body. And how the Cornea bulge focuses the light on the right side of where the iris should be.
The same effect that is visible on the top right where the "window" light is focused through the body.

The Leftside IOR object has caustics turned off ( No global illumination ) if that's what you looked at?

[NicoR44]

love to see where this goes

[Aniki]

I meant, maxwell render doesnt show caustics in your renders, as they would be behind the transparent object.

why is discussed in the given thread, for example

what you mean is illumination actually.

cheers

Aniki

[Lars Magnusson]

Ok Aniki, had to test what you where saying. And now I understand.
The term caustics are only used for the brighter areas where light is focused?
And I thought I got that in the iris area but it was apparantly the slight inward iris shape that tricked me.... a completely flat area would probably have shown the problem more clearly.


Eye Test 2 by LarsMagnusson, on Flickr

From left to right:
1. The previous cheat. Strong indentation of the iris area and caustics off for the external cornea part.

2. The slightly flatter internal iris part with caustics OFF for the external cornea part.

3. The slightly flatter internal iris part with caustics ON for the external cornea part.

Not much differens between 2 and 3 except that 3 takes much longer to render.This cooked until SL17, 20minutes.

So I'll stick to nr 1. Hm or maybe 2. The weaker inward shape of the iris area looks better and gives the light differens I'm looking for.


Also tested the pool-problem that you linked to and if I understand correctly:
Things that are inside a dielectric like the white/iris of an eye or the bottom of a pool will take loooong to show real caustic effects?
Since just the the external eye part without the inner "white" gave nice caustics pretty fast on the floor.

[Aniki]

also like the second better. looking forward to textures and maybe sss ? but careful, I'd use singlesided because of the dielectrics problem too !

cheers

Aniki

[tom]

It's just a particular performance issue with sun and small/distant emitters. In your eyeballs scene, the caustics have no problem.

[Lars Magnusson]

It's just a particular performance issue with sun and small/distant emitters. In your eyeballs scene, the caustics have no problem.

Ah, ok. Maybe a slightly longer "cooking" would have made it more visible in the iris area?
(or placing the emitter better)

Still, a human eye is one of the few situations when turning off the "global illumination" for the dielectric object doesn't affect the render in a negative way.

[Lars Magnusson]

Just had to verify that Tom was right.


Eye Test 3 by LarsMagnusson, on Flickr

The left one has a thin cylinder encapsulated in the external eye-body and the right one has a cube that intersects it. So, flat surfaces instead of my indented iris shape.

Both show the same bright area caused by caustics, focused by the cornea bulge.
Guess it's so weak because I STILL haven't fixed the strength of the emitter....discovered the underexposure in the first render...but never did anything about it

This also cleared much faster than my previous tests.. kind of surprised me!?

[Half Life]

Good stuff... very interested in this for myself as well.

Best,
Jason.

[Lars Magnusson]

Haven't had a lot of time to work on this, but I post this testrender just to show that I'm still working on it.


Eye Test 4 by LarsMagnusson, on Flickr

The texture was based on a photo. Did some attempts to get specularity map and bump map from the texture but the results of that is crappy

However, I will create a new texture by hand in Photoshop instead.
With layers,masks and groups it will be easier to create a base that can be used to create eyes with different colored iris, and also much simpler to get useful bump and specularity maps.
(my idea for the iris colors is to have separate layers for different colors/depths and basically paint the streaks on the mask, then I can fill/paint whatever colors I like instead of just altering hue.)
Handpainted will also give me more control of redness/veins. This eye is rather red and tired so it wouldn't look good if I decided to sculpt someone pretty.
( low chance of that, more likely to be zombies or ghouls when I sculpt )

[tom]

Cool!!!

[Bubbaloo]

That looks great!

[NicoR44]

That eye looks great Lars! woow!