This is a great imaged based measuring app. You can use it to easily measure area and length (distance) for pretty much anything. The app provides unique free form measuring tool so that you can easily measure irregular shapes. They could be as big as mountains, buildings, or as small as CT, MRI images. Just move your finger along the boundary of the shape that you are measuring, the app will tell you the length and area automatically.
In order to get accurate real world measurement, you need to know the scale between image and real world first. Many people use calibration method to get the scale. For instance, they use the app to measure something they know the dimension in real world first and input it to the app to calculate the scale. After that, they use the app to calculate dimensions that they don't know. Once you have the scale, the app will automatically display measurement in real world dimensions.
Besides free form measuring tool, you can also choose other measuring tools including line, rectangle, circle and ellipse. You can easily move or zoom in/out the image and choose the part you are interested. The app also adds up all the lengths and areas that you have measured and tell you total length and area automatically. It supports sending the measuring results out through email.