Parenting Tracking Data to Comp Transformation

[Leonardo01AB]

Hello Experts!

I am newbie and here is my question: I have a source footage in 4K which I initially took to Premiere Pro for some basic editing. The output resolution will be 1080x1080 so one of the main things I did in Premiere was to apply several transformation keyframes (position and scale) within the crop area. I then linked the sequence to After Effects as I thought that having a dynamic link between the two would be optimal for any future edits. In AE, I tracked an item to perfection, no issues there. The problem emerges from the fact that during the tracking analysis, the work is done within the video layer which is 3840 x 2160 (4k) and I imagine that AE stores absolute X and Y coordinates from that area but when I apply the tracking data to a null object back in the main 1080 x 1080, the whole path is completely offset to (what I believe is) the fixed X and Y coordinates from the 4k video layer. How can I make the tracking data coordinates relative to the transformations (position and scale) of the main comp?

Thanks in advance!

[Rick Gerard]

If you are talking about camera tracking you have to pre-compose the cropped and scaled layer before you run camera tracking on the Pre-comp. You don't want to track the original footage. The same thing goes for Corner Pin tracking with Mocha AE. Come to think of it, if you did any manipulation on a video layer you should pre-compose before running any tracker. All tracking uses the original asset from the Project Panel. Effects, scale, everything applied to the layer is ignored. A Pre-comp becomes an asset in the Project Panel so all of the effects applied to all of the layers in the pre-comp will be used when tracking is running.

Your workflow is a little wonky. The way to achieve the very best quality and scaling of your project is to do all of the cutting in Premiere Pro and all of the effects work on the original footage at the original frame size and frame rate. If you want a custom square output, the latest version of Premiere Pro has output options for all of the popular social media formats and it's a lot more efficient. 

[Leonardo01AB]

Thank you for your reply, Mr. Gerard. The tracking in question was a motion tracking. I did all the cutting in Premiere, as you suggested, and it is also obvious to me that all effects should be done in the hires version before rendering in 1080x1080. That is exactly the reason why I linked the original PP project to AE, so that the latter would have access to the full 4k glory for applying effects, as opposed to rendering a 1080x1080 output video and importing it in AE. Apparently, the problem was that I did not consider the need to precomp the source sequence first. 
In regards to a 1:1 aspect ratio output, unfortunately, it is not a simple matter of cropping a 4k sequence into a 1080 square. The whole 4k sequence was animated (translation and scaling) in PP so that the cropped area would always display only what mattered for the video.
Thank you again!

[Rick Gerard]

As I said, motion tracking is always based on the source, not the comp. If you have cropped and scaled footage you must pre-compose that footage moving all attributes to the new comp and trimming the comp to the in and out points of the layer, then run motion tracking in the main comp on the pre-comp (nested comp) so you are tracking the source, not the original out of position scaled and cropped original footage (asset).

[Leonardo01AB]

Thank you yet again. I will follow your advice and get back with my results once I get the chance to try it out.