Compliant Ruler

Throw out a ball for your dog to fetch. Now with an outstretched arm you can easily block your view of the ball with your thumb … until the dog comes running back with it. The ball has increased in size, and to keep it covered you have to move your thumb closer to your eye. Now what made the ball and then your thumb get bigger?

Anyway, the compliant ruler will correctly measure objects almost no matter how far away they are from the ruler or how far away the ruler is from your face. Say you want to know how tall that basketball player is or the height of a building or the wingspan of a circling buzzard. With infrared camera technology the ruler calculates its distance to the object and to your face and adjusts the scale of its markings along its LCD edge accordingly.

Walking away from an object will cause the markings to move closer together. Moving the ruler farther away from your face will cause the markings to expand. The player will always be 7’3” regardless of where s/he is on the court and regardless of how nearsighted you are.