How to use:
Firstly, please ensure that the object you wish to measure and the object of known length (Base Item) are in the same picture. There is a predefined list of Base Items, including Debit/credit card and Quarter. Select the one you have.
Secondly, ensure that the Base Item and the object you wish to measure are in the same plane and the camera is (or was) parallel to them. This is necessary to avoid image distortions caused by the camera perspective.
It is advised to use the Base Item which is closest in size to the object you wish to measure. Given that you have accurately aligned markers, you will receive a measurement that is as precise as when using a traditional ruler or tape measure.