What if I used my credit card as a reference rectangle? Do I have to worry and immediately block my credit card
NO, NO, NO, NO, NO and NO
What am I measuring?
You are measuring the lengths of the objects in the 2D plane of the reference rectangle with a size of a credit card.
Why VisualRuler does not compute height of buildings?
VisualRuler measures only sizes in the 2D plane of the reference card.