3. Process
Click 4 points in order: top-left → top-right → bottom-right → bottom-left. Then click Submit.
Use an image with the card + L-ruler (jig). Camera calibration must be done first. This sets the scale (pixels per mm) so margins are reported in mm. Points and measurements are saved automatically and persist after restart.
Mark two segments on the L-ruler, each with a known length in mm. Click 4 points in order: Leg 1 start, Leg 1 end, Leg 2 start, Leg 2 end. Then enter the real-world length (mm) for each leg. The image is shown at full size—scroll if needed to see it all.
Download checkerboard pattern (9×6) — print at 100% scale, then take 3+ photos from different angles.
Click 4 points in order: top-left → top-right → bottom-right → bottom-left. Then click Submit.