Black Lines Where Mattes Overlap?

[user_deleted]

I have been trying to pull a matte from a greenscreen shot, but am having problems getting it right.

Because the actor has silver/grey hair and the lighting varies on each side of his head, I have it best to use two primatte keyers - one for each side. I have used a rotoshape to matte out most of the greenscreen, leaving a small area around the head, in which to use the keyer. I then used another rotoshape to create a (garbage matte) small window for the keyer to be active in.

Each bit seems to work on its own, but when everything is combined i am finding a black line appear where the original matte intersects with the smaller garbage mattes.

I have no idea what is causing this, or any clue how to prevent/remove/avoid this problem. Any advice would be very welcome.

i have tried the manuals, the paolini books, the quick ref guide, and some tutorial movies, but as yet have not found an answer.

[user_deleted]

it's kinda hard to say without knowing how you combine things..
why dont you just paste the script code here?
++ christoph ++

[user_deleted]

Try to use the rotoshape in the mask, not garbage matte, of primmate

[user_deleted]

QUOTE(lightningad @ 03/13/06, 08:09 AM) [snapback]230889[/snapback]
...but when everything is combined i am finding a black line appear where the original matte intersects with the smaller garbage mattes.

This is typically a premultiplication problem

[user_deleted]

i have found it to be a combination of my own inexperience at creating and using roto's, and using an Over node where an Iadd was preferable.

I think its working now. thanks for the suggestions.

[user_deleted]

I personally think Max is a better oprion than I add for a number of reasons.

firstly it will allow you to preserve blurred edges better rather than in creasing the values of grey pixels where they overlap, and when working in float iAdd can do funny things !