the 3D masks takes any xyz / position / normals pass and outputs a mask. You have the option of different shapes and you can also rotate them. I use this one a lot for color correcting or depth effects on 3D images.
3dMattes
Updated: 19 March 2011
Author: paurocher
Compatible Nuke versions: 5.0 or later
Compatibility: Linux, Mac, Windows
See short description ...
Example script provided.
Usage:
0. Set your viewer in RGBA mode.
1. Under 'Point pass' choose the pass you want to use to extract a matte from.
2. Click the 'output' button until it says: 'side by side'. Your image is going to be the double its size in the y axis (don't be afraid, this is normal!!).
3. Select the color picker on the 'point' knob and sample a color on the upper part of the image (the pass you selected to extract mattes from).
At this point you can play with the rest of the knobs (shape, expansion, fallof, modify shape, rotateX Y Z, center).
Note for rotations: if you drag the color you picked in step 3 to the 'center' knob, this is going to become your center of rotation. Pretty useful ...
4. When you are happy with your matte you can click again on the button 'output' until it says 'mask'. Your mask is going to be output using the channel you selected in the 'output' knob (the last one).