Hatched lines when masking

[Olaf]

I have this problem regularly and wonder if anyone knows (a) what causes it and (b) if there is anything I can do to improve the mask:

Let us imaginee that we have a fast moving action filmed with a static camera from the front; I don't know, let us say a chef chopping a vegetable. Behind him is a wall. On that wall there is also a camera (filming him from a different angle). Thus, that camera is in shot from the front camera. What I do is duplicate the layer and put it on an underlying track. I then mask out the camera (I have to use key frames because the shape of the mask will change as his arm comes up and down covering more or less of the camera behind him as the case may be). Then using layouter I move the underlying track slightly so that the 'hole' created by the mask is filled in with another bit of wall. Hey presto the camera behind him disappears.

Because the action is fast and not necessarily uniform I usually have to key frame the mask on each frame. I sometimes use a feather sometimes not. This is where the problem starts. I draw a perfect mask using bezier curves. Frame 1 perfect. I move to frame 2. Adjust, perfect. I move to frame 3, adjust, perfect. But, now frame 2 has messed up and part of the inside of the mask around the circumfrance is hatched (so translucent in effect). The mask is not covering all the area. I move the mask again. Now frame 3 is messed up. This happens whether using feathering (soft outside edges or not an just using harsh lines). The only thing I can think of is that Edius is not able to change the mask rapidly enough and there is some form of transition between key frames? It is really annoying.

Any help?

[zvit]

Edius can't "transition" (interpolate) between key-frames if you are key-framing EVERY frame, since there is no wiggle room. In such a case, you should be feathering the inside of the mask (cutting off a bit of arm) and not the outside.

In any case, key-framing every frame manually is a big no-no. You will always end up with a some jitter or artifact. To get the best results you should export the footage and bring it into After Effects and use a combination of "find edges" and "Auto Trace". Google it and you will find many tutorials on how to do so.

There will be no magic mask for this since depending on the color of the chef's jacket (white I suppose) and the color of the wall behind him (usually white too), this will be manual task that will require tweaking.

Maybe you can make some general ovel mask around the working hand and blur out the background so you "pop" the hand and blur out the camera in one swoop without a lot of work. Or, if the quality of the footage permits, scale the image up until the other camera disappears. You can also scale it up a little, shift it the left or right, fade the cropped line that is created on the side and overlay some other video or logo to cover the black sidebar.

You can also yell at the camera guys for filming front and back of the chef, which probably broke the 180 rule anyway.

Other suggestions:

Make the footage appear for a shorter time. Key-frame the footage so it pans slightly. (The viewer will have a harder time finding flaws in moving footage as opposed to static footage since his eyes are moving, most likely following the main action which is the cutting hand. (and if the rule of thirds was applied... if not, move the footage to get the hand in an interest point).

Make a ROUGH mask around the hand (you can SLIGHTLY key-frame a moving mask) and make everything around the hand black and white, keeping color to the hand. (Again, turning the viewer focus away from the background.)

Studies show that when the subject is interesting, viewers seem to not notice other things going on in the shot, especially if it's short.

Good luck!

[Olaf]

That is SO useful. Really. Really. I am going to all of the things you suggest and try them out. Seriously, I really appreciate the tips and ideas. Although I use AE, I use Edius so much that I don't have any time left of my spare time to learn all the things it can do. Find edges seems to be a brilliant tool and I'm going to go off and read about it right away. I like the idea of panning too...good thought.