How to measure distance and height using camera on your iPhone or iPad with Telemeter app.
iOS: https://goo.gl/CNQvbS
Telemeter - app for quick remote distance and height estimation using only camera live view.
Height of the camera needed for accurate measurements. If height is unknown, you can calibrate the app using known size length (person's height, sheet of paper, etc). After app calibration auxiliary horizontal lines can be used as a rangefinder.
Music: https://incompetech.com/