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yorkshiretyker
10-17-2008, 05:59 AM
I've been trying to get this to work for the past two days :( and just can't for the life of me work it out, and I bet you my bottom dollar it's a doddle and I'm quite sure I've done it before using alpha channels.

I have a tennis ball modeled in Lightwave which I want to export so that I can get rid of the background in Sony Vagas, so that you can see a video in the layer behind.

hope you can help :)

YT.

gerry_g
10-17-2008, 06:11 AM
only 32bit formats will output alphas, so save as – tga32, psd32, png32 etc,
I prefer png cos the alpha is integral to the image and pops up in PS sans background without any faffing about, at least it does on a Mac

gerry_g
10-17-2008, 06:15 AM
ps. if you have an item/s behind your objet in the scene make sure their alpha channels are set to constant black in the render options of the object properties panel first

yorkshiretyker
10-17-2008, 06:33 AM
ps. if you have an item/s behind your objet in the scene make sure their alpha channels are set to constant black in the render options of the object properties panel first
Thanks for that - but just another slight problem The white in my object is also becoming transparent Is there a way around this? :(

Jockomo
10-17-2008, 08:04 AM
It's either a problem with how you have it set up in vegas (you're probably using a luminance key instead of an alpha key)

or the surface that is white is actually transparent and you had a white background set in layout.

gerry_g
10-17-2008, 02:06 PM
Or set the alpha to 'constant value' for the object thats giving you transparency problems, this is going from memory but fairly certain I'm right

yorkshiretyker
10-17-2008, 05:33 PM
I'm still not getting it :( - I've wound rendering it with a blue background and using the chroma key.

I don't think the result is as good as it would be with an alpha channel - if someone would be able to walk me through rendering the alpha channels out of Lightwave, as I think there is something I have to be doing wrong.

Cheers,
YT.

dwburman
10-17-2008, 11:04 PM
I don't know Vegas, but with Final Cut you sometimes have to set the clip properties so the editor knows that there is an alpha channel.

You can see the alpha channel in Lightwave's image viewer after you do an F9 render. You do this by selecting "Alpha" from the pop-up menu in the upper right corner of the image viewer. This way you can check the alpha channel to make sure your white areas aren't partially transparent. When viewing the alpha channel, white is opaque, black is transparent and shades of gray are something between the two. This way you can know if the problem is with the file LW is saving out (assuming you're using a file format that contains an alpha) or if the problem is Vegas interpreting the file correctly.

If you can share the scene (or one like it) that you're having the problem with, then someone else might be able to tell you if there's something wrong with it.

gerry_g
10-18-2008, 03:55 AM
If this is movie/animation footage the 32bit thing is erroneous, it's more about having the 'save alpha' option checked and a valid file path set under Render Globals < Output, in this instance 24bit is fine as it's a standard channel.