View Full Version : clear label on glass bottle?
10-16-2004, 08:43 PM
This one is driving me up the wall. I am trying to model a bottle of Smirnoff ICE/Twisted. The labels on the bottle are clear PVC (or whatever material). The bottle itself is transparent. I have created a UV map for the entire body (midsection) and hope to create the front and rear labels through a combination of scanning and Photoshop.
So then... I have been experimenting literally all day long on how to get the opacity of the graphics and the transparency of the label. I just can't seem to get there. I am testing with both a 32 bit PSD and 32 bit TGA file. This leads me to a sub-question - the alpha channel in LW. I know how they work in PS and After Effects, but in a fog over how they're used in LW. They do not behave as they would in other programs.
Has anyone done this before? Any advice?
I'm not sure if I need to create separate geometry for the label or not. I suspect not... but... ?
You can see a small photo of the bottle here (http://www.gpi.org/Awards.html) under the Malternatives category.
10-16-2004, 09:19 PM
What exactly is the specific problem you're having? I've had problems trying to use the embedded alpha channel in a psd and wound up just making a seperate bitmap with the alpha image in it.
10-16-2004, 09:31 PM
I may try your idea of a separate alpha channel.
My specific problem is getting the transparency in the label while showing relatively opaque graphics. I am going to also need to bump the label to show the outline. (not as important right now) The screenshot shows my label in Photoshop with the transparent areas.
I had this problem before when making a ciroc vodka bottle. I had a gradient controlling color/opacity (the bottle fades to a more opaque purple at the bottom) but I also needed the decals to work...if i remember right i had to make separate geometry for the decals and slightly offset them from the glass surface (disable cast shadow so they dont look weird) and then use the alpha channel for a clip map in layout..
10-17-2004, 12:33 AM
wow... that looks really sweet.
I am getting close... but now I can't finger out what's causing the band around the middle.
I'm going to try your technique... as well as hammer more on this dang label on the same geometry.
10-17-2004, 01:20 AM
Very possibly, the computer is adding brightness to the pixels that are covered by the transparent band, because the alpha-value of that transparent area is not set to zero. (Incidentally, I think the brightness achieved within the band is more to my liking; without it, it's too dark.)
Take some before and after pictures and, with Photoshop or something like it, measure the resulting RGB values at various area pixels... in the various component pieces and in the final image. See, quantitatively, what is actually happening. That should explain a lot of things.
Since the label is an opaque thing that's attached to the bottle, the alpha of the opaque areas should be 1.0 while the band, visually, does not exist at all. (If you do want the clear band to be slightly visible, it should affect some other channel of the output but not "brightness.")
P.S. Don't fall in love with how a bit of the word "Smirnoff" appears in the left-hand bottle. In real life I don't think it would ever actually do that. Especially not in a surface of a slot which appears to slope away from that bottle. You don't want that to be "the brightest thing" on that left-side bottle. Plan to brighten-up that back-side label: no matter what it does in real life, you can't afford for the brightness of the labels to be that different in a printed image. Since it contains small text, make sure the left label is tack-sharp. Zoom in three inches; crop to within 1/4" of the bottom of those bottles; that specular reflection on the bottom of the frame ain't payin' the rent. And why are those bottlecaps slouching up there? Fill the frame. If it ain't subject, cut it off. The best tool in a photographer's pouch is a knife.
10-17-2004, 01:52 AM
whoa... ease up there, cowboy. While I do appreciate the advice and tips (I really do), this is just a "test scene" to show what's going on with the labels. This is by no means what the final scene will look like. I wish I had a digital camera.... or I would take a photo of the bottle so you can see what I'm talking about.
Imagine a clear label with 2-3 graphic items on it. Those items are inset from the edge of the label by at least 1/8". I am trying to show the slight hairline edge of the label (bump) while maintaining its transparency... and yet showing the opaque graphics printed on the label.
I swear... if I get this right it will be some sort of miracle. To make matters worse, portions of the labels are metalized and therefore extremely reflective. The backside of the neck label is entirely metalized.
I may take some digital video of the bottle and see if I can't extract a decent vidcap to post.
10-17-2004, 03:05 AM
To properly have the label behavior you want you pretty much have to build out a separate object to be the label..doing it all through layers on the skin of the bottle and at the same time tweaking glass settings, while it might function, it's really more trouble than it's worth, and especially since you need the back of the labels to be metallic, it doesn't make sense to do it as one single object..the real bottle isn't built that way, no reason the cg one should be either.
As far as using the alpha from the PSD, what I usually do with any embedded alpha is create an instance of the image set to Alpha Only, then use that image as the Alpha for misc. layers and settings on the surface, bump, etc...pretty straightforward. Worst case, save out the alpha separately and use it that way.
note-wise, without a long tear about composition and photography, on the modeling side I think your bottle appears to bend in in the middle, should be straight sided..unless that's an optical illusion. One other stupid observation, Triple Black has black caps, regular Ice has red caps, at least the ones I've got.
P.S. Main key to doing surfs with lots of layers and etc. is remembering "Invert Layer" is there..heh.
10-17-2004, 05:24 AM
the real bottle isn't built that way, no reason the cg one should be either. Hmmm... (smacks forehead) That makes sense. :thumbsup:
One other stupid observation, Triple Black has black caps, regular Ice has red caps, at least the ones I've got.
I started out modeling a Smirnoff Twisted bottle. (have not got to the actual twist yet) You will also note that the Tripple Black bottles do not have that lump in the neck, whereas the Twisted does. :) You're looking at a Tripple Black cap on a Twisted bottle with an ICE label. :eek: It's Frankenbottle until I get this label thing squared away. I have this nasty habbit of jumping ahead and surfacing before I finish my modeling. I think I have ADLWD (Attention Deficit Lightwave Disorder)
Regarding the sidewall of the bottle, I think it's within tollerance. It might be off by 1/32 to 1/16th. It's blow molded anyway... so there's going to be some variance in the shape. Here's a wireframe for reference.
Thanks for the advice... I am now going to model separate geometry for the labels... may as well model it as it is in the real world.
01-19-2006, 01:00 PM
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