FieldProtractor

Field Protractor is an app that allows you to measure angles in a photograph. Take a photo of an angle and line up the protractor arms on the screen to tell you the angle.

It also allows you to measure the length of an object in the photograph by setting the scale against another object of known length. Overlay the scale line to an object you know the length of and you can set the scale to find the length of any object at the same distance from the camera.