View Full Version : Alpha Transparencies for textures

05 May 2003, 02:18 AM
Okay, I have no idea what the heck I'm doing.

What I am attempting to do is build some "leaf" textures for some trees I built in Maya. My professor showed us how to go about making alpha transparencies for these textures in Photoshop, but I'm pretty stumped.

The question is this: How do I go about making an alpha channel for my tree leaf textures so I can get the transparency to work in Maya? Also, where does on go to mess around with alphas in Maya?


05 May 2003, 05:18 AM
Well if you know how to create Alphas in P-shop, then it won't be too hard to transfer it into Maya.
As you know an Alpha channel is in greyscale. Black for zero selection, white for total selection. It basically works the same way in Maya.

Say you have a leaf you have made in Photoshop, or scanned (what I like to do). You Just select out all you want. However you do this, there are many ways. You need to make two files, the exact same size for this to work. One is the color file of the leaf, I suggest making the background on this file something close to the color of the leaf edge. Flatten it and save it, but don't close the file.
Then you need to save the exact same file but only a black and white cutout (Alpha see) of the leaf itself. You can feather the edge of the cutout a bit if you want to, but not too much. You dont want it too wispy looking close-up.

Now when you bring the image into Maya you only have to do a couple of things.
1) Make the shader, you can use a PhongE for this, it usually works good. Then when you select the shader in Hypergraph or Multilister, hit CtrlA, or double click on it. then where the color attribute is for the shader click on that little 4square checker pattern on the right. Select a file of your leaf, .tiff .iff or .jpeg usually work best.
2)Repeat the process for the Transparency attribute on the same shader, but this time select the Alpha that you have made seperately. Now this should just cut the leaf out perfectly and you may not need to go any further.
3)If this doesn't work entirely, you need to go into the connection editor. The easiest way to get the ConEd to pop-up is to drag the Alpha over the shader (it should work).
Then you need to connect the Alpha RGB values to the Transparency Red, Green and Blue values.

I made this a litlle long winded, but hopefully everything will work out perfectly.

05 May 2003, 05:50 AM
Here, I dug this up for you.

05 May 2003, 01:41 PM
Dear Majewski:

For your info, PS versions 6 and 7 PS are no supporting any longer alpha channels in some image file formats, such .tga or .png.:shame:
You should use other formats that Adobe is still suporting, like .psd or .tif. :annoyed:
The reasons for this, probably, are strategic commercial interests.:thumbsdow:


05 May 2003, 03:44 PM
You are incorrect. Adobe still fully supports an Alpha Channel in TGA image files in Photoshop 6, and the latest patch for Photoshop 7.

There was a small hickup with the format in the comercial release of Photoshop 7, but as I said this was fixed in the patch (and was caused by Adobe being a bit dim, rather than any cunning strategy).

We should put this information in a sticky thread or something because someone seems to have to mention it at least once a week...

05 May 2003, 04:37 PM
Ya that was a pretty huge 'hiccup' on Adobe's part, I couldn't believe'll want the 7.01 update that Harlequin was getting at then you can use targas and stay away from jpgs

05 May 2003, 10:29 PM
Thanks for the help, dmcgrath. I'll see if I can get this in for my animation for class. I'm sure it will look better then me using dead trees! :D

adri80386, I'm using *.tif files for my texture formats. My prof wants them that way. Thanks for the info about the other formats though.

05 May 2003, 02:27 PM

sorry, but wath i´m trying to do is to avoid the tremendous time wasting that such problem causes until you, finally, chosse a diferent saving format ( probably .tiff or .psd ).

ps6 also lacks of alpha handling in .tga

i disagree with you that is an adobe´s hipo.

has anybody been able to install 7.0.1 version ?.
on the old times of PS 3.0 and small capacity hard disks there was not RLE compression for .tga and had to choose a different saving format ( probably .tiff or .psd ).


05 May 2003, 05:36 AM
You have to be doing something wrong. Photoshop has full support for Alpha channels. It's true it was a release problem that they didn't put something into the original release of v.7.0. But 7.01 should have no problem with Alphas. And the upgrade is free.

CGTalk Moderation
01 January 2006, 06:00 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.