Expert: LizaL - 3/27/2006

Question
hi liza. here is what i'm doing. i've made a 3d computer rendering
of a building i'm working on in a program called form-z. i can save
the image out as a tiff with an alpha channel. what i want to do is
to use the alpha channel to mask the image of the building so that
i can place a sky behind it. i've done this before but forget how. the
results i've had in the past where that where there's no building i
get sky and where i'm looking through glass, i see sky but with
some less than 100% transparency. can you walk me through this
process step by step? thanks.

Answer
Hi Ben,

I don't think I can walk you through this process unless I can see the image. Why don't you email it to me (as long as it's not huge! and if it is, maybe you can reduce or crop it). My business email address is lizal@little-works.com

Be sure to send me the Photoshop file, and not a compressed version like a .jpg. I'll be happy to take a look at it and see what might be going wrong, and see if your alpha channel workflow is best for what you're doing. There are a lot of different ways to mask in Photoshop.

Maybe you can also send me one of your previously-saved images that turned out right -- that might help me see what you're wanting to achieve.

Thanks,

Lisa