View Full Version : UV map transparency issue!

sean hargreaves
05-26-2009, 10:58 AM
Hi Guys,

I have a glass bottle I want to put a graphic on. But the glass is transparent and the graphic needs to be opaque. In Photoshop, where I made the graphic, I can make the background transparent, but when I map it onto the glass, the transparent layer is now white.

What am I missing here? Thanks.

sean hargreaves
05-26-2009, 02:54 PM
I've attached some screen grabs.
1) My Photoshop graphic. Note TRANSPARENT background and solid 7.
2) My quick test render. Note the surface I have applied the map is now a number 7 on an OPAQUE, not transparent background.
3) My Texture Editor window.

Is it the type of file I'm saving it as? I've tested .psd, .jpeg, .pict, .tif, all have the same result.

I'm lost. Any help or suggestions would be greatly appreciated.


05-26-2009, 03:05 PM
I'm pretty sure you have to apply that texture as a clip map (it's under object properties - you may need to tweak it a bit too) in order to accomplish what you want.

I know it seems odd...

sean hargreaves
05-26-2009, 03:23 PM
Sorry RollerJesus, that did'nt work. I can't understand why, when its saved as a .psd with a transparent background, it has a solid background when imported into Lightwave.


05-26-2009, 03:33 PM
Hi Sean,

You need to create an alpha in Photoshop then save the image in 32bit which saves the alpha with the file. You can use the PSD format or save a separate TGA or PNG or any other 32 format. When you load it in you should make sure that ALPHA is enabled in the image editor.


05-26-2009, 03:43 PM
Photoshop transparency does not control surface transparency in lw - if it did, you couldn't put a decal on a model plane without it turning transparent! You'll need to apply a b&w map - usually made from the alpha - in the transparency channel of the surface.

sean hargreaves
05-26-2009, 04:41 PM
Ok guys, if i've got this right - I load the graphic into the transparency section of the surface editor after i've saved it as a .psd with an alpha. And I have Alpha enabled (not alpha only) in the image editor. Do I load it also into the color section of the surface editor? Also, Toby whats a b&w map, I cant find it?


sean hargreaves
05-26-2009, 05:01 PM
Ok guys, I got it sorted out, everything works fine until........Dielectrics, where the whole thing including the number 7 dielectricizes. I did a none-node refraction image........its just not the same thing.

Any thoughts? What have you guys done in the past?

05-26-2009, 05:53 PM
Doing this with dialectric would be a bit tricky, stick to layers for now. Load in the psd into the image editor, clone it there and change it's alpha option to "alpha only". Use the original in the color channel and the clone in the transparency channel.

b&w just meant black & white, which is the same as the alpha-only option. The alpha is just a map of 0.0 - 1.0 (or 0-255) values, just like a b&w or greyscale image. And this is the only value that the transparency channel reads, color data doesn't get used.

sean hargreaves
05-26-2009, 07:06 PM
Thanks so much Toby, I'll try those suggestions.


05-26-2009, 07:12 PM
toby is completely right but I tend to be a bit confusing so I create two images...the colored one for the color channel and a black and white / gray picture for the alpha. And save them in 24 bits format. and use the separate gray picture for the transparency etc. I had some confusions in the past with the 'use alpha only' etc.

About dielectric...using the material mixer node doesn't work for you? inset dielectric in one of the slots and the other material (standard as an example) in the other and use your grey image for the alpha. It works in here.

05-26-2009, 08:52 PM
Oops, I didn't read Sean's post correctly...what Toby said...:thumbsup:

05-26-2009, 09:07 PM
About dielectric...using the material mixer node doesn't work for you? inset dielectric in one of the slots and the other material (standard as an example) in the other and use your grey image for the alpha. It works in here.
Maybe we should show you that too, it saves you from having to set up all your own glass parameters. How much have you used nodes Sean?

05-27-2009, 08:46 AM
Sorry for the mis-advice there Sean, appreciate all the info from trolling this thread. :)

05-27-2009, 09:05 AM
If you don't use nodes, then you'll find that for varying transperency in a single surface you will always need both a 'colour' image and a 'transparency' image (for something like a label the latter just being white for transparent & black for not ) (antialiasing the edge gives you greys of course). Apart from using the B&W image to give you transparency (base transparency as 0% and image 'normal' @ 95% or whatever), you will also need to user that B&W image in the same sort of way to give you the different diffuse,specular & reflection values etc. between the label & the glass - paper label with glass specularity & reflection just doesn't look right!
I've found that using psd images is fraught with problems - they are big files, take up lots more memory than they ought, and LW still isn't very happy if you try to use multiple instances of the same image file with different image editor adjustments to them.

sean hargreaves
05-27-2009, 11:10 AM
Toby, I'm still a relative newbie with nodes, I use them mainly for dielectrics and sub-surface scattering, not much else right now. I tend to learn what I need at the time and grind through.

Thanks everyone for all your suggestions, I'm working on them today and I'll see how I do. :thumbsup:

05-27-2009, 01:27 PM
No better time than the present! Like Adrian was saying, you'd really need to use the b&w map in most of the channels so that your label isn't as shiny as glass, if you use the layer method. The node method skips all that, and will get you more accustomed to nodes, which is they way of the future!

So, as Zardoz was saying, you need a Material Mixer node and a Standard material node, both under Materials. The dialectric plugs into A of the Mixer, and the Standard into B. Your b&w / alpha map plugs into Alpha. Set up the Standard node how you want your label's surface to look, without worrying about the shape of the decal. And that should do it.

05-27-2009, 04:31 PM
and if you get the label transparent and the bottle opaque simply click on the image map and choose invert.
by the way I recently did a few bottles for advertising and I modeled the labels. It gets that nice thickness. If it is for closeup shots this would be the best, and more realistic option.