2. THE KEY TO UNDERSTANDING MAPS

CÓMO REALIZAR UN CORTE TOPOGRÁFICO:

 

SYMBOLS ON A MAP

Maps can be drawn to represent a variety of information. This information might include things such as roads, tourist attractions and campgrounds, or they might represent the latest weather patterns. The objects on a map are represented using symbols. A symbol is a picture on the map that represents something in the real world. Understanding these symbols requires the use of a key. Maps use a key, or legend, to explain the meaning of each of the symbols used in the map. These keys usually show a small picture of each of the symbols used on the map, along with a written description of the meaning of each of these symbols.

II. SCALE ON A MAP

Remember that a map is a visual representation of a much larger area of land. In order to be useful, a map must by necessity be small enough to be handled by an individual. Imagine drawing a map of the Earth that was full-size. Of course this is ridiculous. A full-size map of the Earth would not only be too large to be useful, but it would also be impractical to make. Maps are scaled down so that they fit on the available paper or screen. When scaling down a map, every part of the map is scaled by the same amount. This insures that every object on the map is the same proportion as everything else on the map.

Because the Earth is round and maps are flat, it is impossible to create a map with a perfect scale. Some parts of the map will be too large, while others will be too small. The larger a territory represented by a map, the greater that the distortions in scale will be.

  • A Graphic Scale depicts scale using a line, with separations marked by smaller intersecting lines, similar to a ruler. One side of the scale represents the distance on the map, while the other side represents the true distances of objects in real life. By measuring the distance between two objects on a map and then referring to the graphic scale, it is easy to calculate the actual distance between those same items. There are many benefits to using a graphic scale. First and foremost, it is a straight forward, easy way to determine scale. Secondly, if a map’s size is enlarged or decreased, the scale is also enlarged or reduced, meaning that it is still accurate.

  • The fractional method for portraying the scale of a map uses a representative fraction to describe the ratio between the map and the real world. This can be shown as 1:50,000 or 1/50,000. In this example, 1 unit of distance on the map represents 50,000 of the same units of distance in the real world.

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