By entering the height of the target, to shoot under point and the top point, this app is an application which you want to measure the distance. 

On the other hand, it is also possible to measure the height by entering the distance to the object, to shoot in the same way.
It is also possible to view enlarged at the time of imaging.

If in a state where the target is obliquely, is its diagonal length (not height) is known, that it be taken to tilt (iPad) iPhone, little, precision you will be able to increase.