Using the Titler to draw masks -- how put it together?

Question

For lack of a rotoscope function in PPro (16 point garbage matte being the limit), I tried using the Titler to draw a mask, but can't get the transparency to work.
The base clip is a static skyline shot.  Using the Titler, I created another title clip, using the base clip, with a mask drawn around the sky.  The idea is to make the area enclosed by the mask transparent, so as to replace it with the sky from another shot -- and retain the rest of the base shot, which (on the Titler) is the area outside the mask.
But, using these 3 clips on 3 tracks, and the track matte filter, I can't get it to work.  Any ideas?

Answer 1

The main issue you're facing might be in the fact that Titler doesn't create a shape with alpha channel. Hence, your should set your Track Matte Key to 'Matte Luma' instead.
Here is briefly how to create procedural matte in PrPro:
1. Duplicate your footage in the sequence, place it above the previous one and apply Threshold effect onto it. Adjust Threshold Level to taste so as to get more or less acceptable edges with the sky keyed out. Apply Fast Blur to soften edges a bit.
2. Open up Titler and draw a shape for garbage matte. Set Graphic Type to Filled Bezier and Color to Black.
3. Drop your newly created garbage matte above your footage with Threshold effect and nest them.
4. Apply Track Matte Key onto your lower clip and set Composite Using to Matte Lume.
5. Enjoy.