"Astra. Was dagegen?"

[arneoog]

My Cola Bottle got ior: Cola 1.02 and Bottle 1.15
It's low, but if I set it higher the glass will apare way to thick
Probably cause of the powerfull lights in the scene...
And yes, it's modelled the Real Life way

I got two side by side renders soon finish, one Real Life and one Thomas An.
One with ior: Glass 1.3 and Fluid 1.2
And one with ior: Glass 1.15 and Fluid 1.1

EDIT: here it is

[OnoSendai]

Here's an image I made:



To model such a scene as the one pictured, The model needs to be set up so that each of the three interfaces can be assigned a different material.

The material for the air-glass interface will be a standard specular material with (internal) index of refraction (IOR) ~= 1.5.

Note that currently in Indigo it is implicitly assumed that the 'external' IOR is 1. (i.e. very close to the IOR of air)

By 'external', I mean the volume on the normal side of the interface.

The air-water interface will be a standard specular material with IOR ~= 1.33

For the glass-water interface, I'll define a new property for the specular material: external_ior. This will define the IOR on the external (normal) side of the surface.
So for the glass-water interface, the usual internal IOR will be 1.33, and the external_ior will be 1.5.

This technique may be something of a burden on the modeller, but it should produce good results.

[OnoSendai]

Hmm.. forgot to add, I would appreciate if someone could model a scene in the way I have described and chuck it up to download, or send it to nickamy AT paradise DOT net DOT nz.
I'll take care of the materials.

[lego]

lowpoly... if it's ok I'll send you the 5kb zipped xml

edit:
I've sent it... it's just 5kb, so it shouldn't be a big problem even if it's not ok

[debris]

I'm not a physicist, but to me it looks like the liquid's and the glass' refractive indices would add up (which is wrong) if the scene would be modeled according to the picture above, because the lightrays don't get kind of "reset" by exiting the refractive material but directly entering another refractive material that bends the direction even further. This would explain why even with a refractive index close to 1 the result looks so strange.

[OnoSendai]

Thanks Lego.

Debris:
in real life, as far as i know, there is no air layer between the water and glass.
The Fresnel equations and Snell's law will handle the glass-water interface refraction and reflection fraction correctly, even if neither of the media are water.

[manitwo]

For the glass-water interface, I'll define a new property for the specular material: external_ior. This will define the IOR on the external (normal) side of the surface.
So for the glass-water interface, the usual internal IOR will be 1.33, and the external_ior will be 1.5.

Cooooooool !!!

[Kyokutan]

How about this?



The 2 Meshs overlap to one object. The left one get a colorless spec mat with just ior and the right only transparent colored spec mat with IOR:1

This should avoid color errors...but doubles the polycount.

(Not tested yet)

PS.: MS Paint forever

[Pinko]

How I can make the shader glass like this bottle in Cinema4d.....
Where I can find a tutorial for indigo shaders???
Tnx in advance.
Pinko.

PS:For inexperienced users tests are very difficult without a basic documentation...

[OnoSendai]

11min test render using new technique:



Seems pretty good, hard to tell tho

[tungee]

[manitwo]

indeed ... looks good

[debris]

Thanks Ono-Sendai for your reply

I didn't mean there really is a thin layer of air between water and glass, but I wondered if the ray of light knows it's exiting one medium and entering another without passing through a surface with an inverted normal and entering another medium by passing through a surface with a facing normal. MentalRay e.g. would interpret it like 2 added IORs which would lead to false results. It either needs a small gap between the two Materials or a shader that offers 2 IORs to be entered (like e.g. the T2S Illumination Shader's "Media In" value): the IOR of the Material and the IOR of the medium it's coming from (most of the time "1" for air).

To be sure I made a simple test:


A textured floor plane, one glass window with thickness and IOR 1.5, another thick glass window in front of the first (on the left side) same IOR but a tiny gap between window 1 and 2 and last but not least a simple one-sided grid with IOR 1.5, too. This covers window 1 on the right side.

Here's the result in XSI/MentalRay:


Result in Indigo 0.66 (sorry for the burn, it killed the .EXR file while stopping the rendering so I had to use the tonemapped PNG ):


Notice that there's no XSI-exporter yet, so I exported it via Blender / OBJ and positioned the camera by hand to give a similar angle.
Result in both renderers is the same. As you can see, the IORs on the right side add and results in a very high (=3) IOR while on the left everything looks as expected.
Should be similar to the water in the glass-problem?

[Kyokutan]

Test of my system with green glass and dark yellow fluid.


1000 mutations per pixel


But i got to shrinken the color "layers". When they overlap with the IOR "layer" i get nasty artefacts.

[OnoSendai]

Kyokutan: i presume you are worrying about the colours of the objects due to absorption. This is an issue, but I think it can still work using my technique, I just have to be careful coding.