4K footage & HD composition

[MahaB82A]

In this YouTube tutorial there is a 4K video but it is worked in HD. What is the reason for that?

3D CAMERA TRACKING

Time 0.37-0.57

[ShiveringCactus · Accepted solution]

I imagine the video's creator is trying to reduce the processing requirements to work on a smaller area.  3D tracker tends to analyse the whole video, ignoring in- and out-points so sometimes it is worth precomping just what you need.  I see his preview blocks up, so probably his system can't quite manage a screen-recorder plus 4k video.  Or he worries it can't

[MahaB82A]

Thanks for the help.