Fusion / Mocha Pro Newb Roto Question

In Mocha, I tracked a complex shape and exported the tracking data to a Fusion comp file. I also exported the shape mask to a roto .ssf file. I then opened the comp file in Fusion and imported the shape file and linked the shape file to the mask input on the tracker. My problem is the shape mask is not located in the proper location and the size is too small. The problem seems to be because the roto shape has a center point and the tracker has four corner points. Am I doing something wrong?

Apply the roto mask to an bg, then apply that to tracker, and use the output.as bitmap effects mask.

Yep--although if you're doing a corner pin, you can select Corner Pin mode (I can't remember the exact name) in the options for trackers. There's a good tutorial on this on the eyeonfusion channel, by the lovely Germanic-sounding chap. He's a boss.

Fusion applies things relatively to their size. So if you apply a polygon or bitmap mask directly to an object that's smaller than the frame, then it will scale respectively in size. You can apply it to a BG which will set your frame size (apologies for my poor terminology) but you could also just pop in a transform on the shape and set it manually. Which is a bit crude but it works.

When tracking in mocha with perspective, the key is to make sure the exported positions of the track in mocha will match the image ratio of what you are feeding into it once it goes to fusion. Not sure it fully relates, but best to explain by example.
If i'm tracking a face and want to replace the eyes, I'll set the tracker output in mocha on the frame that has the least perspective, and/or is the largest on frame and set the blue export box in mocha to the aspect ratio that I think can cover both eyes.

Once in fusion, I go to that same frame, take the same BG (the face I tracked) image and crop it around the eyes roughly to match the 4 corners location on the BG, and feed it back into the 4 corner track. I make adjustments to the crop and/or add perspective or warping to get the same eyes back into the face. Once I've done that, I now know exactly how my foreground image needs to be setup in relation to the old eyes, in order to replace them correctly.

Now the crop becomes my BG template image for my new eyes. Get them in the right place merged over that crop, and they will line up

Yes, there are many ways to do this, and I think you can even prep your foreground and bring it into mocha to align it there, but i'm not that verse in Mocha to make that claim.

Of course, if you don't need perspective, then change the imported tracker which defaults to 4 corner, and choose match-move as the option.
This method is good to do a standard match-move using the tools of a planar tracker.

Loved to know if this helped at all

None of the above worked. I found this tutorial late last night. I'm going to try the create a polygon approach and then import my shape file to it. And then link to tracker.

If I had a better understanding of what you are trying to do, I could help a bit more. I know there are a few issues going between Mocha and Fusion, for one, mocha exports comps at frame 0, even if your clips start at frame one etc..

I would be better equiped to help if you can post a video showing you problem. There are many ways to skin the cat between fusion and Mocha.

hi,
as i undestand You did the tracking and also roto'ed the complex shape to be replaced,.
But when You imported everything into fusion the shape ibs out of place?

the first thing to check is default comp size in preferences>frame format - make sure it is the same as in mocha.
also do check the frame offset in mocha and in fusion, make sure that the frame numbers are the same (yeah, Rony - that pesky TC-based frame numbers... )

when everything matches File>Import>shapes should work
Shape importing from mocha imports: rotoshape animation and a center-Path animation (the path mocha tracked for the shape). That is why You have a center in shape and 4 trackers in tracker

What You probably would like is connect the original footage into the tracker (or just export track from mocha and ctrl+c / ctrl+v in fusion). Connect the replacement to the Tracker as a FG, in tracker /operation set the match move >FG only.
Than connect the mask into mask input of a tracker.. should work, however if You would like to share a file / comp, the help would be more detailed.
Sometimes the export from Mocha is "somehow broken" - try exporting one more time

Thank you Marek. The default frame size was the problem.