A map angle meter is a tool that allows map angles to be expanded or measured.
The map angle is the right-angled angle between the card nest and a known direction. The map angle measurement may be provided with a coordinate system on maps.
The card angle meter usually consists of a transparent semi-circular plastic, or a kind of angular ruler. on which a distribution in degrees is applied (degree bow). There are also fully circular card angle gauges, as well as card angle gauges on which outside the above distribution, other data, such as a ruler (10 centimeters), and a location indicator are provided.
With a map of 1 to 25,000 and 1 to 50,000, a coordinate of up to 10 meters can be accurately determined. However, cards with a different scale are not usable.
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