I'm currently working on a beer advert in Maya.
I've finished rendering the whole 30Sec. advert with my fantastic beer bottle model that's got one layered material with my beer content, nice realistic-looking glass, & labels.
Everything looks photorealistic... client still wants one detail... those cool little condensation droplets all over the surface.
Any ideas... preferably something that could be done with alphas & masks in After Effects... and not stuff involving displacement / bump maps in 3d... that means re-rendering from Maya, and my deadline just won't allow for that.
You don't neccessarily have to re-render the whole scene tho. Try this:
Take the beer bottle model, and apply a useBG shader to it. model or create particles, (however you want to do it), to create your droplets on the bottle. Asign your water shader with refraction to that. Then put the actual rendered image of the bottle sans water droplets behind the use bg bottle and droplets. When you render, you will get refractions,reflections on the droplet from the image you put in the bg. Since your only rendering droplets, this should render really quickly. Since this method will not generate a correct alpha (because of the bg plane), render out another pass with a white lambert on the droplets for the alpha channel pass. (kill the bg image and crank the abient color of the droplets to white). Combine these on your rendered image and voila, you have refracting droplets.
hope that helps
Usually one could use a transparency map to cut away unwanted geometry right?
But what if your geometry's completely transparent (like glass) & only visible because of it's refractions/reflections.... how would you cut away geometry using a map on a completely transparent object?