#Alpha & fog/dist cue
3 messages in this thread
How would one go about getting the alpha channel to take fog or distance cue
into consideration? I want to creat an overlay animation of some text and
would like the text to fade in from the background on top of the background
image. All the attempts I have made at using fog or distance cue to generate
the appropriate alpha channel have failed. All the text shows up in the alpha
channel when only a portion of the text can be seen in the image. Any
suggestions short of manually editting the alpha images?
Daniel (C.S.I)
Daniel,
One easy way would be to render your text using black fog or distance cuing,
but assign a self-illum white material to the text and render the full sequence
in 8-bit, saved as sequential GIFs. Render the background normally, as TGAs.
Render the text normally, but without fog, as TGAs. Then you would use the GIFs
as the Alpha>RGB Mask in VideoPost for the text TGAs. Your queue might look
like this:
1 BACKGROUND (sequential TGAs)
2 TEXT (sequential TGAs) / ALPHA.RGB Mask=FLC you made
Render it as a FLC to test.
Good luck!
Eric Chadwick at Mechadeus/Mondo Media
The method Eric gave you should be just what you need. In the upcomming
"3D Studio – Special Effects" book (due out this month) I wrote a chapter that
goes into detail on doing this type of composite. Just render your animation or
image normally, then render another version of it with a self illum white
material (ambient, diffuse, and specular colors should all be 255,255,255)
assigned to your objects, and with depth cue on. This will be used as an RGB
mask for the frames to be composited over the background. Works like a charm,
but I would suggest rendering the alpha frames to TGA's and not GIF's. It
depends on your disk space and quality needs, but GIF is not really a true
greyscale format, so they can produce dithering artifacts in the grey areas
that can dirty up a composite. But they do require less space, so it's up to
you.
David