Is it possible to measure distance to object with camera?

Question

Is it possible to measure distance to object with phone camera?

I mean, in my application I start the camera, facing the camera to the object (lets say house) and th

Answer 1

Well you should read how ithinkdiff.com "measures" the distance:

Uses the angle of the iPhone to estimate the distance to a point on the ground. Hold the iPhone in front of you, align the point in the camera and get a direct reading of the distance. The distance can then be used in the speed tool.

So basically it takes the height of where you hold the phone (eye-level), then you must point the camera to the point where object touches the ground. Then the phone measures the inclination and with simple trigonometry it calculates distance.

This is of course not very accurate. It gets less accurate the further the object is. Also it assumes that the ground is level.