Apply Tracking Data to flopped shot

[Arivl]

Hey folks, I've got a 3D camera from a matchmove artist (and a few dozen nulls) that tracks a shot of a car moving down the road. I'm going to be adding some VFX to it, but unfortunately first I have to flop the shot horizontally.

Of course, this wreaks havok with the tracking data.

My first thought was to just parent everyting (cameras & nulls) to a 3D null and invert the x-scale on the parent.  No joy, though.  Cameras don't like being flopped, apparently.

Then I tried adding expressions to invert the x- and z-rotation of the camera, but that just resulted in a mess.

Any ideas about how I can take this matchmove data and get it to line up with the flopped shot?  Thanks so much!

[Mylenium]

It's one of those "Why even bother?" things. What can you not do on the original source shot that you could  on the flipped shot? Sure, you'd have to keep in mind the mirroring, but it seems you are making this unnecessarily complicated. Do your comp work, flip it in 2D in a parent comp.

Mylenium

[Arivl]

Yeah, that was my first thought.  There's a longer answer to that, but the short one is that the pipeline for this shot is already pretty bent out of shape, and it's going to make things way more difficult if everyone has to flop all their work on the shot (3D cars, etc).

If I have to go the "why bother" route, I'm going to end up having the flopped plate re-tracked from scratch.  But I'm hoping to avoid that.

[Roei Tzoref]

Instead of scale, did you try use 3d rotation? Z rotation 180, the Y rotation 180 I think