View Full Version : Wavy glass in Mental ray

05 May 2009, 08:27 PM

I'm using Maya 2009, and I would like to achieve the wavy effect you can see in the following links:

Please tell me, how can I go by doing that?

Is there a map that can distort the refraction or I just have to sculpt the surface of the glass to make it pshysically wavy ?


el diablo
05 May 2009, 08:44 PM
make it a bump or displacement and dial in the refraction. If you want to do i in comp run a normal pass to distort the image behind...el diablo

05 May 2009, 09:05 PM
Thanks El Diablo,

I think I am a bit closer.

I attached the map I plugged in the IOR texture slot.

The first render it's with a blinn and raytrace render, however in the second render where I used Mental Ray, I couldn't achieve a similar effect to the one in the raytrace.

I tried rendering in MR with the same blinn, and I even gave MIA_Materiar_X with Thick Preset a shot, I also plugged the same map in the IOR Slot, but with no luck.

I made sure I have enough ray depth under Raytracing.

And one more thing, if I put a map onto the IOR, how can I adjust the position and the way the texture is applied? Do the UV's the model already has, apply to all maps?

Thanks once more.

05 May 2009, 12:24 AM
In my opinion you don't have to use any map in the IOR channel, you have just to plug a bump or use a displacement map; the images you attached shows different kind of glass that have distorsion onto their surface caused by age or cheap quality or intentionally perturbated surface, it's not a matter of refraction.

05 May 2009, 08:01 PM
Plugging to the Bump Slot, shows the image attached.

I used MR, 0-2 adaptive sampling, and mia_material_x with thick glass preset, which I modified to use the map as a bump map.

The result is... terrible.

el diablo
05 May 2009, 08:33 PM
there are many things I would need to look at to fully debug. What do the UV's look like, what is your sampling, are you tiling the image, etc...

05 May 2009, 10:17 PM
...would stay the same, roughly, as the substance (in real life) isn't changing, only the shape is changing.

You can model in the waves using simple brushes in Zbrush or Mudbox, but the standard way to do this effect is with bump mapping, especially if you want fast render times.

05 May 2009, 12:07 AM
Try to smooth or blur your bump map, increase bump filter, use quadratic filter on your bump texture...there are a lot of things you can do to improve your terrible result, just test test test ;)

06 June 2009, 03:13 PM
with the bump of the mia_materials that work well :)

06 June 2009, 05:49 PM
How does your map look like? It makes it hard to figure out what lies behind.

06 June 2009, 07:28 PM
...but I'm not trying to insult you. Just saying that I found it pretty straightforward to replicate various glass types using mia_material_x and the Standard Bump slot.

Took an old scene from Chief Architect to test it real quick. The glass doors are both single Maya cubes stretched to fit. One face per side. Nothing fancy.

GlassFrosty preset:

Glass Thick preset:

At this point I realized my Final Gather depth wasn't high enough, so I set it to 2,2,4.

Glass Physical preset:

Looks okay, now for the bump-mapping.

In all these examples, I'm using a simple Maya 3D texture node attached to the Standard Bump slot in the Glass Physical preset. I change the bump strength to .1 (instead of 1) to smooth it out a bit, and rarely use bumps at the default 1.0 anyway. The texture nodes are otherwise unaltered, in their default states from here on.

Glass Physical with Sold Fractal bump:

Glass Physical with Cloud bump:

Glass Physical with Marble bump:

In my opinion, the Cloud bump worked best, a bit sharper and cleaner than the Solid Fractal. The Marble bump would be awesome with a few tweaks, but as you can see making wavy or obscured glass is rather simple, or should be.

Combining the Glass Frosty with say the Cloud bump would likely produce a pretty nice result, and mimic obscure shower glass pretty well.

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