# How to learn card scale

The topographic map – a projection of mathematical model of the real area to the plane in a reduced form. That how much the image of the area is reduced and is called a scale denominator. In other words, the scale of the card is the relation of distance between two objects measured according to it to distance between the same objects measured on the area. Knowing card scale, you will be able always to calculate the actual sizes and distances between the objects located on the earth's surface.

## Instruction

1. An indispensable condition of the edition of any topographic map or scheme is the indication of its scale without which it loses the meaning and becomes just beautiful survey picture. Usually the scale of the card is specified in its description – a legend or is taken out in marginal registration. It can be specified both in heading, and together with the explaining inscriptions below. Sometimes, on popular schematic cards the scale is written by pryam on the card. Attentively look at the card and find the inscription "Scale 1:" or "M 1:".

2. If the card is cut off and marginal registration is absent, it is possible to determine required scale by other map of the same territory which scale is known. Find on both cards on couple of same characteristic points of the area. Life of the building or industrial constructions, road crossings, characteristics of a relief which are reflected in that and in other card can do it. Measure by a line of distance between them according to both cards and calculate the relation between scales – how much required scale more small or more largely specified for other card.

3. Keep in mind that, usually, scale this whole, multiple 100 or 1000 value. If at you the value of scale not it, then it at the expense of an error in measurements turned out therefore result the scale of the card in such value.

4. If there is no second card, then you will be come to the rescue by high technologies. Use one of cartographic services which are available in Yandex or Google. Their basis is formed by the space pictures transformed on a flat surface, in essence – cards. Find on them the territory which is represented on your card with an unknown scale and those two points which you chose as characteristic. Using the Ruler tool, determine distance between these points by satellite images in those units of measure which you choose. Knowing a map distance and distance on the area, determine the scale of the card and result it in the whole value, multiple 100 or 1000.

Author: «MirrorInfo» Dream Team