Scaling

So that each model has its real size and the zones line up with each other (see Aligning chunks), I measure distances on the site during the dives: two targets placed on the bottom, the distance between them measured, and both targets filmed with the rest of the zone. The distance between two targets makes a scale.

Targets7.5 and 15 cm

Kindcoded, Metashape

In pairstargets 1 and 2

The targets

Targets of 7.5 cm and 15 cm, numbered in pairs (targets 1 and 2).

2024-08-02Both kinds of targets on zone 5's floor: a 7.5 cm one (top) and a 15 cm one (bottom left)

Their pattern looks abstract, but each one carries a coded number. They are Metashape’s circular coded targets: the black dot in the centre marks the exact point to measure, and the black sectors of the ring around it make the code, each position on the ring a binary digit, black or white. Metashape reads that ring in the photos, recognises each target’s number and finds the same target from one photo to the next.

(to be completed: how the targets are printed and protected, how the distance is measured underwater.)

Next

In Metashape, the targets are detected in the photos and the scales defined with the measured lengths: the column “Targets detected / Scale(s) defined” of the progress by zone.

(to be completed: the steps in Metashape.)