Fast ice cube render

[seth0x2b]

Anyone?! :(

[FloydBishop]

If you render with raytracing, you can get that look. It'll still render rather slow though. There are a lot of calculations going on to get that refraction.

[JulianS]

this is an example i made for the L_glass(froster) Forum... I explain more there

http://forums.cgsociety.org/showthread.php?t=334264&page=2&pp=15

http://creating3d.com/Help/ice.jpg

[irwit]

Id say julians looks alot nicer but thats personal preference. Instead of rendering raytraced reflectrion and refractions why not try using an eviroment map instead of raytracing, should knock your renders down to a few seconds

[seth0x2b]

Ok.I got it up and running using l_glass (GREAT shader btw).
The problem is that it's far from being fast (1.5 hours of render for a damn cube :( ).
I think it takes that long because it has way to much geometry(I had to sculpt alot of deep bumps in the cube so I can get the kind of reflections that I want(.
My question now is: how can I create "fake" reflections on a simple,non-bumped(or poorly bumped) cube?I need to limit my geometry so I get faster render times, but no bumps mean no nice reflections.I need this type of swirly-wirly reflections http://koti.mbnet.fi/who/images/icecube.jpg
but alot more, with greater detail.
I read somewhere on the forum that I could use a bump on the reflectivity channel or something like that. How would I do that?!

10x alot. Cheers

[AndrewRaZ]

sounds like you're making your ice cube a lot more complicated than necessary. you could easily get the same effect with a simple cube with beveled edges a good bump map, and maybe even a refraction map with something like render clouds from photoshop (though you might have to put the file node through a math node or something, since the maximum output a file can have is 1.0. you don't need to use the bump on the reflectivity itself, as the bump will perturb the surface normals and affect the reflection anyways. i don't know if the I_glass shader has a bump node though, and if not, i'm not sure how you would go about hooking one in.

also, your environment and your render globals are going to affect your render times. do you have production set in the render globals? that will increase render times for sure. i don't know what you're using for the reflection source in your environment, but i really hope that isn't fluids we see on the bottom there. that'll crank your render times up exponentially. also, whenever you have two surfaces reflecting/refracting/and sorting transparency, you're going to have a lot of render time on your hands, which is what you have with the water/ice cube effect there.

hope this helps some.

[seth0x2b]

I don't know if l_glass has a bump channel( I'm just starting using mental ray shaders) but I am able to create bumps with the following method:
1. Create a base l_glass shader
2. Open the input - output connections where I have l_glass1 plugged into l_glass1SG.
3. I then create a maya displacement node and plug that into L_GLASS1SG
4. Create the bump I want (checker for example) and plug it into the displacement node.
That does the trick.
This is the only way I know to bump a l_glass textured object.

I will try to get the effect using a bumpmap(I tried that first, but it still didn't render fast enough).The only problem I have with bumpmapping the cube is that I can't seem to get a good displacement map(I need the result to be smooth). I tried some fractals, even the water texture, but still can't get the right bumps.That's why I just modelled the bumps with the sculpt geometry tool.

The cube in the water is not what I am making.That is just an example to show what kind of surface "effects" I was going for. I have no other liquids or glass materials. Just the cube, ground plane, IBL enabled, Final gather enabled, one spotlight and 2 surface planes for white reflections.


Cheers

[JulianS]

use regular displacements with approximations, That render was only 2 minutes

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