Author Topic: Beer Fail - Render Challenge  (Read 5013 times)

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Offline justindustrial

Beer Fail - Render Challenge
« on: March 08, 2011, 01:13:05 am »
I'm not too sure if there have been any render challenges on here, but I thought it might be fun to see how different people approach the same problem, if you're keen.

I fired this off last Friday for some friends back home, but wasn't too happy with the results, maybe someone out there would like to out-do me?

Basically the scene was to have a cold, crisp gold one with sweaty beads of condensation running down the glass, something to really wet the palette... Good luck to anyone interested!

And then of course the winner will have to explain how he/she got all those nuances to work in KS.

Offline andy.engelkemier

Re: Beer Fail - Render Challenge
« Reply #1 on: March 25, 2011, 07:36:42 am »
This actually looks really nice. Quick advice for liquids through glass though. This applies to many 3d applications actually.

when two refractive surfaces meet you need to change the IOR out to be that of the immediate next surface. On round surfaces this usually doens't product correct results though because you eventually need to get back to an IOR for air, which for rendering purposes we'll say is 1.0

So 2 workarounds. Not sure which is better in keyshot.

One is, instead of having an inside surface for the glass, just split it where the liquid touches the glass and remove the inside glass. That way the refraction method would go Glass,Beer,endBeer, endGlass. This should give you a more proper IOR. Right now it looks like the beer is floating inside the glass instead of touching the surface.

The other method doesn't work in all 3d apps, so you'll have to try it out, but it's easier. Simply expand the beer so it's Just inside the volume glass surface. It's wrong, but in most cases it will look close enough to correct that most people won't notice. So for this technique you'll actually want to make sure a little of the liquid is pushing inside of the glass. This makes sure the liquid is seen before exiting the glass surface. You'll get incorrect refraction, but it will at least look like it's touching. Like I said, less correct, but often it's a faster way to give the results you might be looking for.

Offline JeffM

Re: Beer Fail - Render Challenge
« Reply #2 on: March 28, 2011, 01:16:41 pm »
Thanks for the good info Andy!

The wine glass scene we've included with KeyShot has proper surfaces and IOR settings and serves as a good example for those looking to do liquid in glass renderings. The materials are even set up to do proper color with the "transmission out" settings.

Offline andy.engelkemier

Re: Beer Fail - Render Challenge
« Reply #3 on: March 28, 2011, 01:39:01 pm »
When using this method for doing liquids inside of glass don't forget to be extra careful about tessellation. If you zoom in closely (or render really large) you can see that the tessellation actually doesn't match where the liquid meets the inside glass liquid interface.

For those who don't quite get how that's done: The main color, Transmission, is the color of the liquid. Upon exiting that color we have to define the transmission out. This should match the color of your glass in this case. That's why it's a slightly bluish white. The same goes for IOR. 1.333 is water, so that might work for most liquids in (wine is probably closer to 1.4 if you're trying to get super accurate, since it has sugar and alcohol in it which are both higher than water) and glass is usually closer to 1.6 but can very quite a bit.

Anyone try the other method? I'm curious if that works in keyshot well. I know it's less accurate but you don't have to pay Quite as close attention to tessellation, which is a bit of a bonus.