MOCHA Tracking affecting Transform Properties

Hello, Very much an AE MOCHA noob here.

I have a shot where i need to track a blue flame on a propane burner.
The blue flame is stock footage and i’ve re sized it and applied a color key effect.
I then took the studio shot and used mocha to track the nozzle on the burner as the actor holds and moves it around.
Everything seems to be coming together except when I “Apply Export”. Once the tracking data is exported to the blue flame layer it re-sets to its original size. Since Mocha is over writing the transform information how can i resize and adjust another layer and then track it in Mocha? I tried to pre-comp the blue flame layer but AE crashed when i tried to export the tracking data to a pre-comp. Also thought about using a null object which i’ve used when doing some camera tracking.

Appreciate anyone’s help

Mocha’s tracking is all about “the surface tool”. If you have already resized and positioned your stock footage before applying the track, I would advise you to precompose that layer. Then in Mocha AE, (before creating and applying the track data) you choose “Align Surface tool” to full frame. Make sure you do this on the frame that you used to match the scale and position (typically the first ref frame).

Also be aware of what kind of track data you are applying: Corner Pin for perspective OR just transform to get the general x,y, rotate and scale. Certainly applying track data to Nulls is a valid workflow when using transform data.

There are a lot of tutorials about this subject:
https://borisfx.com/videos/align-surface-and-mismatched/
https://borisfx.com/videos/sign-replacement-with-mocha-pro-align-surface-and-insert-module/
https://borisfx.com/videos/mocha-explainer-understanding-co-planar-and-the-surface/

Hope this helps

Thanks, that helps point me in the right direction. Appreciate it.

So I got my shot really close but the Flame still wanders off the nozzle of the burner…

The biggest fix was making sure the align surface tool was turned on at the first frame of video.

anyway heres what i have right now. Super close but not perfect. Any suggestions on how to adjust it?

https://adobe.ly/2XYbsTE

You can use adjust track in Mocha to adjust this. Or, in your comp, you can take a null and parent your flame to that null and animate an offset to correct this. Either of those techniques will work.

Cheers,
Mary