Learn more about the design and functionality of the curvimeter. A curvimeter, also known as a map measurer, is a device that measures the length of curved lines. With a curvimeter, the distance between points on a map can be determined more accurately than with a ruler or compass. The mechanism includes a measuring wheel, a dial, and a pointer. When the measuring wheel is rolled along a line on a map, the pointer moves to indicate the units of measurement (centimeters, inches, etc.).