Which standard is used for calibration of the measuring tape and ruler?

Easy Measure shows you the distance to objects through the ruler camera.  Simply aim your camera to an object in your surroundings, and Easy Measure displays the distance towards that object on top of the camera image using the Smart Ruler Scale Tape Measure. Ruler scale measures multiple units of length used to measure the distance.  A ruler allows you to take a photo and measure object length or area. Measure objects on the screen using a smart rule scale app or take photos to accurately measure. You can easily measure length and distance with the ruler camera app. 

Measure everything with a beautiful on-screen ruler app. Choose between inches and centimeters and measure any photo easily. You can measure the distance to the object automatically at the base of the object, measure the height of the object, and calculate any object distance at any time. You can measure the length of everything by using the camera of the smartphone using the ruler camera app. ruler measure is a simple and easy to use measuring tool for quick measure of the object's length. This ruler helps you conveniently and accurately measures the length of everything with your phone anywhere, anytime. Ruler app allows you to measure the approximate distance and height of an object by using your phone's camera. The ruler is an intelligent application by which you can precisely measure the dimensions of any object or item. Use a ruler scale Measure to calculate distances between objects using your camera!