An opisometre or curvimetre helps reading the distance on the maps. Although manual methods exist, curvimetre offers the most accurate and time-saving method. Yet talking about one of the manual methods, you can measure the curved path by dividing the route into segments and measuring the distance of each segment one-by-one. Then, add all the segments to calculate the total length. The manual method is all about careful observation, precision, and time efforts. But, curvimetre can do that in a few seconds.