I'm trying to put a paper label on a glass bottle. I've seen several tutorials that explain how to do this, but they typically use rectangular layers. I want to use a cylindrical texture map, because the label wraps around the whole bottle. My texture generally consists of a layers list. First there's a Whole Object layer that defines glass, then there's a Cylindrical layer that defines the label. Doesn't work. The label comes out transparent and reflective, not like paper. When I juggle the settings the label disappears. Or the glass disappears. Or Carrara slows to a crawl. About every 20 minutes Carrara stops responding to mouse clicks. I've struggled with this for 5 hours, and now it's time to beg for help. Has anyone done this seemingly simple thing? Also, as a side question, I'm using PNGs with transparency for my image maps. Is it possible to take advantage of that transparency in Carrara, or do I need to use a greyscale mask? I originally built this scene in Cinema 4D, which I no longer have access to. In C4D you just apply a glass shader to an object, then apply the label, and you're done. I can't imagine why Carrara's texturing is so cumbersome and unpredictable. It's frustrating. Thanks in advance for any help. - Joe

Hi Joe,

Labels in Carrara are a little convoluted but also very powerful. There are a couple of things that will "get you" if your not watching for them. You do need to create a layer list but you can have the rectangle "label" shape go completely around the bottle like I did in this instance.

I've had the best luck using multichannel mixers to create labels. In Layer mode, Carrara 4 doesn't respect the alpha masks of either .tga or .png files. (it does on billboards or single multichannel mixers when applied into the color channel)

So, you have to mix to multi-channel shaders with what you would usually consider to be the alpha mask. Here's what usually "gets" people: if you don't fill in the empty channels in the label shader (transparency, shininess, etc.) it will inherit the traits from the glass shader. (this is why most peoples labels look washed out; they're transparent just like the glass) This is a huge benefit when adding type to rusted, dirty shapes because it will inherit the grungy stuff from the other shader.

So, it's more complex, but more powerful.

Hopefully the picture helps. I just realized that you can't see what the "Source 2" is in that I've mixed. It's single channel transparency with a value controlling it set at 0%

Mark

Message edited on: 09/13/2005 18:49

You, sir, are my new best friend. The key was the inheritance issue you described. Once I put values into the transparency, refraction, etc. for the label, everything started to fall into place. In fact, after some tinkering I discovered as you can see that Carrara did honor the alpha channel in the PNG texture, and I was able to eliminate the opacity mask altogether. This may be partly due to the fact that I am applying the label to a shading domain, not to the whole object. I don't really know - there are still some grey areas in this process for me. I also turned on "premultiplied alpha" in the texture map, which gives the ketchup smears on the glass a nice thinned-out edge. Thanks very much for your help. - Joe

Joe, that one looks very realistic. Did you also use HDRI for rendering? Ringo

There's an HDRI background, but no sky light because I ran into the problem where sky light doesn't pass through transparent objects. The main hunk of ketchup in the bottle is an object, not a texture, and when I turn on Sky Light the ketchup turns black. Kind of a bummer.