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View Full Version : High End frosted glass help - Mental Ray

TheBeals
12-16-2009, 09:47 PM
Hey everybody, Any lighting gurus out there that have experience with lighting glass and have a couple tricks up their sleeves-I am in need some great tips and advice in creating a material/ light setup such as in this image:

http://www.designer-daily.com/wp-content/uploads/2009/02/sohne-vineyards.jpg

More specifically, the Black bottle in front. I am using the Arch&Design/mia material. I have been switching between Max and Maya trying to get the look I want with no success.

I believe I have a close representation of the material itself, but I cannot for the life of me get it to have the frosted look near the base and the glossy look near the top like in the image. It is just frosty all over-I know this is due in part to reflecting/refracting bounce light from the plane, but even with different plane and background sizes I've tried, I can't attain the look. It looks like the plane is quite long behind the camera to get the long reflection in the front of the wine glasses. Here are my material settings:
http://jdbeals.com/website/pics/big/Material-Settings.jpg


I also noticed that it is mainly using 2 reflection cards for it's main lighting source and maybe a couple diffuse lights on the side. To mimic this, I have an HDR with two reflection cards in it in about the same place as this image. I have also tried placing my own softbox/reflect cards in by hand to get highlights and have gotten decent results, just not high end results. I am also using the photographic exposure control

In max I've used the hdr with the skylight and fg, in Maya I've used it with fg, I've also had it emit light and emit photons and nothing near this quality.

I've looked up a bunch of actual photography books, but none describe lighting with this technique.

Thanks for any help guys, I've been banging my head against my wall for a couple weeks now.

Cheers
kelvincai
12-17-2009, 07:22 AM
I think the frosted bottom you think is the reflection of the white floor. The whole bottle should be glossy and shiny. You could try turn up the glossiness back to 1.0/0.9 and see. Turn off translucency. Use Fresnel reflection. Transparency back to 1.0, use Refraction Max Distance to control the attenuation.

Since there is liquid/wine inside the wine bottle, mental ray doc also points out a trick for this case. http://download.autodesk.com/us/maya/2010help/mr/shaders/architectural/arch_mtl.html#Water_and_Liquids

Also, not to put total black (value 0.0) for Refraction Color at Max Distance. A dark brown might help.

From the reflection of the bottles and the soft shadow, there should be only 3 area lights, standard studio setup, in the scene.

The floor has a bit glossy reflection too.

I didn't use mia_material in max much. But, in maya the physical glass preset could be a good start.

Hope it helps.
TheBeals
12-19-2009, 05:01 AM
That did indeed help. Thanks Kelvin! Everything you said was close to what I had going, but it made me realize that I needed to start simple-fix one problem at a time. So, being more comfortable in Maya, I switched back to it. Applied basic glass mats as suggested in that glass tut and by you. And instead of using reflecting planes, I used area lights with visibility turned on and intensity cranked to 30-also suggested by you. Got the first one in place then the second, then I messed with the floor, I ended up having to turn on refl_dist in the glass so I wouldn't get the harsh line of the floor, but it worked just fine. So here is the wip that I've gotten so far. Pretty close to the likeness of the reference in the link of my first post. Thoughts? Suggestions? Thanks Kelvin!

http://jdbeals.com/website/pics/big/WineBottleRender.jpg
kelvincai
12-21-2009, 10:50 AM
Sure, grad it helps. It is very good.

After a party before the holidays, I realized the red wine bottle is just green. The dark appearance actually comes from the red wine inside. High quality wine has a more transparent red, while the less quality one has some translucency.

A bit too geeky even at parties :p
TheBeals
12-22-2009, 01:18 AM
Woah! That is some cool bits of info-I never knew! That's pretty neat. So the higher class wine you can see more behind it or is it lighter? As in for higher class wine would your refr. falloff distance be greater or would the refr. falloff color just be lighter? Thanks!
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