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BUZZFX
10-17-2005, 09:57 PM
Problem:
I cannot get C4D to make an alpha channel (see image 2)

I want to make a black channel or Alpha mask of my water drop, so I can mask out the background in Photoshop, but after reading the manual and trying this I can't get it to work.

The Cinema 4D Manual says:

Alpha Channel

The entire alpha channel is masked if you use a Sky, Floor, Foreground or Background Object in your scene. Do not use any of these objects if you need the Alpha channel.

1. I deleted my "Sky" object. I have no "Floor" objects in the scene, only 2 "Plane" objects and no "Foreground" or "Background" objects in the scene.

2. I then selected "Alpha" from the render options, and saved my C4D file as a separate file named "waterdropalpha.c4d", but after I rendered it the alpha was all white, not like I wanted in image 2.

Please try and tell me where I am going wrong.
basti
10-17-2005, 10:06 PM
hi paintguy

well an alpha channel will be calculated for every visible object.. so if your planes are visible (guess you gradient in the background is mapped on planes) your alphachannel will be completely white of course. you can use object buffers instead or simply replace you backplane with a backgroundobject which will not be visible in the alphachannel.

basti
JoshKirk
10-17-2005, 10:27 PM
use a compositing tag and take off "scene by camera" for the objects you dont want showing up in your alpha channel
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10-17-2005, 10:27 PM
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