Bezier on the move

vitalforces wrote on 5/24/2004, 11:41 AM
I know this can be done but I can't work out how. I'm trying to put a moving bezier mask over an object during two seconds of DV footage in which the camera pans in a right-to-left sweep, following a passing vehicle.

The vehicle is a 1944 Kubalwagon in a WWII movie, and the object is the distant front edge of a 1994 Chevy that some crew member didn't park completely out of sight before the panning shot. So--I'm trying to make the bezier mask move with the car, frame by frame, as it zips from left to right through the panning shot.

As I say, I know it can be done, but would anyone mind walking me through a how-to? I'm planning to put the same footage on a top track, but several frames ahead so that the "hole" in the bezier mask shows the grass beside the Chevy, not the Chevy. If this were a paint program I'd just clone some grass over the spot where the car is, but that doesn't sound doable in Vegas.


Comments

Acts7 wrote on 5/24/2004, 11:54 AM
First open the pan crop icon for the layer your modern vehicle is on.
You will see at the bottom, two (timeline looking) grey layers.
One say position. The other says mask
Click the mask check box.
Now use the pen tool from the left column tools menu.
Draw your shape.
Now move down the timeline to where the vehicle is last see onscreen and click the mask timeline there. Now click the add keyframe icon from the bottom tool pallette. <+> (looks something like that). It will auto add your mask to that location (same shape etc) as well.
Just move the mask to where it needs to be, You shouldnt have to adjust the mask shape or size but if you need to go ahead
Now scrub the timeline from this window.
More than likely the mask will not be perfect and you will have to add more keyframes in between.
You may wonder why not start at beginning and work your way to the end rahter than creating a starting and ending point and working the middle?
You could but I have just found you get a smoother "tween" in your shapes.
If you give yourself a start point, end point then go back and work from start.

IF you need further assitance lemme know.
Also check out this:
http://mediasoftware.sonypictures.com/products/vegas5newfeatures.pdf
Scroll to page 24 I believe it is.
It discusses the bezier masking as well as animating it.

Enjoy
Acts7
vitalforces wrote on 5/24/2004, 2:46 PM
Many, many thanks for your trouble, Acts7. Send me your bill.
briggs wrote on 5/25/2004, 10:54 AM
Acts7's approach is probably the right one, but here's an interesting take I read in a recent post (can't remember who)...

The Secondary Color Corrector has an option to "show mask." If the item you want to mask out has a distinct color, you may be able isolate it this way. Place a copy of your event in a track above, isolate the color with Secondary Color Corrector, and leave "show mask" selected. Then use this as a mask.

Haven't tried it, but it sounds like a possibility.
Acts7 wrote on 5/28/2004, 9:42 AM
Briggs to answer your question. Yes this works SO amazingly well in the right setup. However I may have read too much into it as he said it was on the set of a WWII film that a 1980s vehicles appeared on camera.
Using only that knowledge you would unfortuantely have to draw the bezier / animated mask as there probably isnt too much of a solid color to mask off of.

But again yes you are right. The secondary color corrector works very well to mask if you have a predominant color behind your object. (I dont want you to think Im blowing your idea up - its great advice)
vitalforces wrote on 5/28/2004, 9:53 AM
I did try the secondary color corrector first, because the most noticeable part of the car--the white hood and fender, would easily mask off (and that type of mask, being dedicated to one color, has built-in "motion tracking") but unfortunately other, darker bits of the car's front end still create a "what the heck is that?" response for the viewer. It would have me chaining a separate mask for every gradation of a color in the image, and then eyedropping a color rather than an image, to replace it.

Do I dare suggest motion tracking in a future Vegas?
db wrote on 5/28/2004, 5:08 PM
try NOT to use a key frame every frame = mask chatter ..
try key frame every 12 frames - might work in some places and not in others .. where the mask is not keeping up try 6 every frames ... you want the least amount of key frames ...