I've half cracked this.
The bit I've worked out so far.
Seemed dead simple enough. Duplicate track, use Beziers to cutout the thing I want to stay in focus on top track. Add GB to lower track. That gave me a nice halo around the onject. It dawned on me that the problem is the size of the object is being extended outside the mask by the GB hence the halo. Only noticeable if there's high contrast between what's staying in focus and the background.
That was easy to fix, apply the opposite mask to the background to cutout the object from that, goodbye halo.
That was pretty easy as the object didn't move much and I didn't need the lower track mask any too accurate to get rid of the halo, in this case.
The bit I can't see any way around.
Other object does move a lot, it was fun tracking it by hand but I don't want to have to repeat that for the lower track. Easy solution, save the mask as a preset and apply that to the lower track and flip the mask for all keyframes (you can do this in a few clicks).
Problem is I've now got a worse nasty, very noticeable line where the mask is, bugger. Not a Vegas fault. The upper mask has a small amount of feather on it and that's what's causing the line and I want to keep the feather.
The solution is easy enough, shrink the negative mask on the lower track a couple of pixels and remove it's feather. Here's the problem. Vegas doesn't seem to have any tool to shrink a path. I could do this another way. Use the Bezier to create a multiply mask and feather that using GB ti shink a version of that. Kind of crude though.
Hoping someone whose read this far has any better ideas.
Should mention I didn't find doing the rotoscoping by hand that tedious. There's a few trick that can make it reasonably easy but this post is long enough already.
Bob.
The bit I've worked out so far.
Seemed dead simple enough. Duplicate track, use Beziers to cutout the thing I want to stay in focus on top track. Add GB to lower track. That gave me a nice halo around the onject. It dawned on me that the problem is the size of the object is being extended outside the mask by the GB hence the halo. Only noticeable if there's high contrast between what's staying in focus and the background.
That was easy to fix, apply the opposite mask to the background to cutout the object from that, goodbye halo.
That was pretty easy as the object didn't move much and I didn't need the lower track mask any too accurate to get rid of the halo, in this case.
The bit I can't see any way around.
Other object does move a lot, it was fun tracking it by hand but I don't want to have to repeat that for the lower track. Easy solution, save the mask as a preset and apply that to the lower track and flip the mask for all keyframes (you can do this in a few clicks).
Problem is I've now got a worse nasty, very noticeable line where the mask is, bugger. Not a Vegas fault. The upper mask has a small amount of feather on it and that's what's causing the line and I want to keep the feather.
The solution is easy enough, shrink the negative mask on the lower track a couple of pixels and remove it's feather. Here's the problem. Vegas doesn't seem to have any tool to shrink a path. I could do this another way. Use the Bezier to create a multiply mask and feather that using GB ti shink a version of that. Kind of crude though.
Hoping someone whose read this far has any better ideas.
Should mention I didn't find doing the rotoscoping by hand that tedious. There's a few trick that can make it reasonably easy but this post is long enough already.
Bob.