Hi! ..I'm new to this forum and have little experience with AE and Maya, I hope I can explain myself good enough.
I'm making a Render sequence in Maya 8.0, and compositing in AE 6.5.. I have one poligon figure and several nurbs inside the poligon. I intend to make the poligon semi-transparent, so you can see what's inside. When I render (using Maya software) and see the results, all is good and the image is what you want to get; the problem comes when I import that image (or the entire sequence) into AE, the alpha channel is making something I don't know what it is.
If I drop the A.channel, the sequence looks just as it should, but I loose the channel and can't put other stuff behind it. And If I preserve the channel, then the image looks incomplete, as if you olny get the "hard or non-transparent stuff".
What do I do??.. whats the problem?? Hope you can help me soon, I'm really tired and have tried all image formats and move all in render globals I see.
hmmm, i'm guessing if you look at your alpha channel you'll see that it's one solid colour throughout and not lighter in certain places, those highlights are probably specular in nature and so aren't showing up in the alpha. But in case its not, check your import settings and make sure you're on premultiply alpha. if that ain't it try step 2: or 3:
You could try render out passes, specular, diffuse etc. and comp the specular layer back on or: bring in your footage without the alpha as you've currently got it. Bring it in again with the alpha and use that layer as an alpha mask for your background footage, you can use eiter the set matte filter or a alpha matte. (You'd but these layers above your render).
It's difficult to tell much without actually seeing the alpha channel... but as Silk said if AE is not behaving as if there is a semi transparent alpha (which it apparently isn't, if you cannot place objects behind your layer and see them), then the problem is probably in the renders coming out of Maya.
Although your color channels may show semi transparent areas, the ability to "see through" the layer in AE comes exclusively from the alpha. So you need to look at that in your renders out of Maya and see if you have gray areas in the alpha channel where the semi transparency should be. If you don't, then the problem is with your Maya renders. As long as you use a file format that support alpha it shouldn't matter what you use (I'd go with iff, tif or targa -- and definitely not JPG which will not support alpha).
It could be a problem with the matte opacity of the shader on your transparent object, among other things. However, placing objects inside other transparent objects is often kind of tricky in 3D and it can pay to render in layers instead and put things back together in post, giving you much more control over transparency and the layering of your objects.
Yup, a friend told me that it would be wise to render in Layers, but I don't know how to do it. Do you know any tutorial or an especific book to learn it?
And Thanx all for your help, It's really cool to read!
Just a wild guess, because it so classic and quite frankly would look like that on a dark image like this, AE is interpreting the alha as straight even tough its pre multiplied with black.
Now if the interpretation s straight wcih is what adobe prefers. youd get exactly this because a very dark image with allmost no alpha would produce that.
(open your AE manual to read about how to change the interpretation)
PS yes its basic image manipulation but still almost no one has ever heard of it until they try something like this. (well maybe just maybe before you end up doing things like this you never do anything where it would matter one way or the other)
Yup, a friend told me that it would be wise to render in Layers, but I don't know how to do it. Do you know any tutorial or an especific book to learn it?
And Thanx all for your help, It's really cool to read!
Read Maya's help documentation on rendering in layers.