Rotoscoping Axis vs. Geometry

[Anonymous]

I wanted to ask advice about rotoscoping.

Is it better to only move the geometry points of the mask to match the shape being rotoscoped or to also move the axis of the mask to match the shape.

I find moving the axis initially, then fine tuning the geometry points can be a faster way to work.

BuT the problem is that you are tthen dealing with two different sets of keyframes. Keyframes for the axis and keyframes for the geometry.

This makes it hard to make sure there are not 2 keyframes on back to back frames. Since you cannot see both sets at once.

Any ideas?

[Ramazan]

hi

yes i also use both.

if for example on a given frame i feel i only need to tweak the geometry, i tend to set a key frame for the axis nonetheless this way i know where my keyframes are. ie on any given keyframe, both geometry and axis are keyframed.

this can lead to interpolation problems though and can sometimes create more of a problem but most of the time it works for me. setting linear interpolation helps this though.

cheers

paul

[Douglas Short]

Yes I understand. But I are you saying that you make sure that the axis keyframes and the geometry keyframes should both be on the same frames as much as possible?

Or is it fine to have axis and geometry keyframes on different frames? Or is this bad?

Mike.

[Ramazan]

hi

yes thats what i am saying, both axis and geometry kf on the same frames. That way you keep both the axis and the geom live in terms of being able to go back and modifying the animation of either without wrecking all the work you have already done.

as you say…doing all the axis kf initially and then the geo kf on different frames should be fine…aslong as you don’t then revisit the axis in anyway.

here is an example of what can happen if you do revisit the axis kf when they are on different frames to the geom kf:

you have a kf for both axis and geo on frame 1 and on frame 50. you then kf just the geometry on frame 25. next you kf the axis on frame 40. now if you go back to frame 25 it won’t match anymore as the axis interpolation has offset it, so you fix it by kf geometry on frame 25… now you go to frame 40 and it doesn’t match anymore as the geometry interpolation has offset it…and so on.

paul

[Douglas Short]

Basically, I use the axis as much as possible. Position, rotation and scaling. Then I adjust the geometry for fine tuning. So my question was is it better to have the second set of roto keyframes i.e. the geometry keyframes on the same frames as the axis keyframes, or is it more efficent to put them where they are needed most, regardless of which keyframes the axis keyframes are on. i.e. look for where the geometry is most out of sync. and fix it there regardless of where the initial axis keyframes are.

Your explantion makes sense, but the problem you have described I think can be solved by when you change the geometry on frame 25 you also set a key frame for the axis. Then when you change the axis on frame 40 you also set a keyframe for the geometry. So there is no stray for either axis or geometry interpolation.

Mike.

[Ramazan]

well yes indeed…thats exactly why i said i kf both axis and geometry on the same frames. your solution to the example is doing exactly that.

but if as you say you do it in passes then it shouldn’t matter where you kf the geom, compared to the axis.

I just find its nice to have the ability and go back and further tweak the axis animations, without the hassle of having to keep abreast of the implications of any changes.

paul

[Author]

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