Please help me escape alpha channel madness

Hi,

I'm about to just go crazy. I am doing 3D modelling for a couple of years now and I'm used to the following approach:

1. Do your texture
2. Use this textue to create the "alpha map" (transparency map) (bump map, displacement, whatever)
3. In material editor load those two maps (or three, or four)

Easy - works like a charm - once you get used to threshholds, grayscale conversion and whatnot. Unfortunately - so far I have been absolutely unable to create Targa files this way. I do not own Photoshop and the extreme high cost is just prohibiting this - I have other programs that work like a charm and never had a need for PS - but I have a need for those 600+ $

So - I tried PSP and the Gimp. While both programs can apparently handle alpha channels and save to TGA 32 format I have been unable to "paste" a 8 bit grayscale image into the alpha channel. I could manually paint on the mask, yes, but this is much less precise than my method of manipulating the original image and setting threshholds.

Currently I do not know if I'm merely being stupid, missing the obvious or if those programs really do not allow to paste a selction/image in grayscale into the channel.

Are there - in case it *really* doesn't work - other programs you know of that allow this or is PS really the only one that supports this?

You could try paint.net It's free, easier to use than GIMP and handles alphas. Will it do the other stuff you asking? I have no idea.

I do not ask for anything extra - all I really want is to be able to, is to paste an image (like 8 bit grayscale) into an alpha channel and save as 32 bit TGA. I can do the rest of the stuff in other programs.

I only ask for pasting an IMAGE/SELECTION into an alpha channel - nothing more If need be I can convert to TGA32 with other programs. But I really, really need this ability to paste images into the alpha mask/channel or whatever that particular program chooses to name it.

Ummmm most programs wont let you do that PSP makes the alpha from the image in a different way. You just really dont see them by the same method you would with PS but it does happen. Gimp just applies it to a set color and if you want to make up the "greyscale alpha" which is always black with a white backdrop of the image and it cuts out the black bordering basically. You can do that manually in psp before you use gimp though really..... just copy the layer above and paste a transparent selection so that the white doesnt show. This layer should also include anything that needs to be colored white and in gimp for that layer you remove the black from the alpha on that layer and white from the actual layer (you usually wanna make the white underlayer (alpha or whatever you wanna call it in this case a bit off from the edge and this is usually a better way to do it then relying on the programs default alpha selection which quite often overdraws the edge and you end up with white lines because of it)

Also an example of what your talking about may help me explain it more to what you are trying to do or a better explanation of it......

Check out these links. The first one was an excellent post by Carmilla Mirabeau who pointed out where she found a Paintshop Pro tutorial on this.

The second one is a relink to the tutorial


/109/2b/132863/1.html

http://www.sluniverse.com/kb/article.aspx?id=10190

An example ... ok .... let me try. This is from a Vue tutorial but it shows what I would like to do (I hope).

Let us assume I render a lot of trees in Vue. The scene will look like this:



Vue KNOWS that the background and a lot of stuf are just render effects and not the result of the physical objects. With a simple command I can save the alpha mask of this scene which looks like this:



See how perfectly the fine detail is made? See why I do not want to do this stuff by hand?

So - I have the image (with surplus sky and ground) and I have the alpha map that eliminates those and leaves just the trees (which I want). All (hehe) I have to do is to put the image and alpha map together in a TGA file. A thing I haven't been able to do so far.

The confusing thing is that the elements are called something else in each program and switching between German and English versions makes things even worse. I hope it is clear now what I intend to to - if this is possible with any of the lowcost/free programs I'd be glad to receive a tip which ones can be used and - if possible - how to do it in them.

I see........ this is more plausible with the method i had said. Would you contact me in world to discuss this a bit more i might get alot more talking to you directly as opposed to crossing forums with you hehe. I'm sure i can help you if you would contact me in world. But I do know what you mean. You can create that by hand relatively easily however there is a trick to doing it though . SL's objects your likely not trying to create such finite details but it is relatively plausible...

If I'm reading you right, all you want to do is take that second image, and paste it into an alpha channel, right? If that's the case, then why not simply copy the image to clipboard, and then (since you're using PSP) paste it onto a mask, and save the mask to alpha?

I haven't used PSP in a while, and it's not currently on my machine, so I'm afraid I can't walk you through the exact command sequence, but it should go something like this:

1. Open both images in PSP.
   
   
   
2. On the grayscale image, select all and copy.
   
   
   
3. On the color image, go Layers -> New Mask Layer -> Show All.
   
   
   
4. On the new mask layer, go Edit -> Paste. Since you had the grayscale image on your clipboard, it should now appear, pasted onto the mask.
   
   
   
5. Go Layers -> Load/Save Mask -> Save Mask to Alpha Channel, and then delete the mask.
   
   
   
6. Save as TGA, and upload to SL.

Again, the exact command sequence may be a little off since I don't have PSP in front of me right now to work with, but that should be pretty close.


On a side note, just so you know, using your 3D application's renderer to make individual images isn't exactly the fastest or most efficient way to go about this, but if that's what you're comfortable with, it certainly works.

THAAAAAAAANKS

Lol - I actually had this done, just like you described! What *got* me, though, was the fact that I never *saw* an alpha channel as I am used to with my program (which, of course, does everything but export TGA files with alpha channels). So I thought it wasn't working or I was doing things wrong.

It is weird to see a non transparent image that will, upon upload, be transparent. I always expected the black and white squares to show through when I saved it as alpha channel and this never happened. OK - now that I know how to do it I can finally take another step.

Thanks to all involved!!

Glad you got it worked ot, HtF.

You're right that it's a little weird, or at least maybe less than intuitive, not to have the transparency displayed visually, but just so you know, that's typical of how raster editors tend to do it. As you know, alpha maps can mean all sorts of things besides transparency, so good raster programs like PS and PSP tend not to make any assumptions as to what any particular alpha channel might be for. SL of course interprets RGBA as color+transparency, but other applications could interpret that fourth channel as something else entirely.

As for not being able to see the alpha channel at all, that's one of the unfortunate downsides of PSP. Unlike Photoshop, it has no channels palette. It's a little annoying due to that and other limitations, but for the price, it's hard to argue.

I fully agree. Since I do the channel in another program and only copy and paste in PSP it's ok, though, for me.

It's currently on sale here for 50% off and I think I'll try a few more days and then buy it unless I find my PS 5(!!!) that was somehow bundled with my video capture card - but that was like 6 years ago or so and I cannot find the CD anymore ....

Thats true. Sadly the alpha channel in either case sometimes gets off base . Which is why i prefer gimp over the other 2 for alphas although a few extra steps need to be taken which really arnt all that hard. You just basically make a manual alpha channel as a layer first and make sure the edging is fine in PSP Basically cut and paste image with a transparent background into psp on a raster layer make a raster layer drag it under it then create a another raster layer and make it a black filled background.

Edit the raster under the original images (note that the image should a selection outline and use a white to fill it. then watch the black background and erase some of the white accordingly. then merge it with the black background adding white to other parts you may need to add to on that for the top layer. Then in gimp > filters or whatever > colors > color to alpha. On the layer with the image you want white. On the layer with the black back and the white overlay you want black. Then merge the two making sure all other layers are off and save as a tga and presto =P