Stand the athlete flat against the wall with the reference mark (e.g. your 7′ line).
Shoot from 10–15 ft back, camera level, about chest height. Drag the three lines:
FLOOR, REF MARK, TOP OF HEAD.
Mark the wall in inches up to 10′ (your ref mark can be any height — just enter what it is, e.g. 10′0").
Step 1: athlete stands flat-footed, arm straight up — photo, drag FINGERTIP to the fingertips, tap Set standing reach.
Step 2: athlete jumps and touches as high as they can — load a video of the jump (slo-mo is best), scrub to the peak, drag FINGERTIP to the hand, tap Set jump touch.
Vertical = touch − reach. Recalibrate FLOOR/REF on each new photo or video.