![]() ![]() ![]() ![]() For example, it is common to see “one inch represents one kilometer” or something similar written on a map to give map users an idea of the scale of the map. Some maps, especially older ones, use a verbal description of scale. One important advantage of graphic scales is that they remain true when maps are shrunk or magnified. The figure has scale bars for 1 mile, 7000 feet, and 1 kilometer. Scale bars are graphical representations of distance on a map. This topographic map has an RF of 1:24,000, which means that one unit on the map represents 24,000 units on the ground. Representative fraction and scale bars from a United States Geological Survey (USGS) topographic map. The representative fraction is accurate regardless of which units are used the RF can be measured as 1 centimeter to 24,000 centimeters, one inch to 24,000 inches, or any other unit. The figure below shows a topographic map with an RF of 1:24,000, which means that one unit on the map represents 24,000 units on the ground. With the numerator always set to 1, the denominator represents how much greater the distance is in the world. The most commonly used measure of map scale is the representative fraction (RF), where map scale is shown as a ratio. A map can have a representative fraction, graphic scale, or verbal description that all mean the same thing. Map scale is represented by a representative fraction, graphic scale, or verbal description. Map scale measures how much the features of the world are reduced to fit on a map or more precisely, map scale shows the proportion of a given distance on a map to the corresponding distance on the ground in the real world. When we visually represent a region of the world on a map, we must reduce its size to fit within the boundaries of the map. The earth’s surface has an area of over 500 million km 2 and any picture of the earth that you can easily carry can only show general outlines of continents and countries. Projection mechanics, types of projections, and their characteristicsīy the end of this chapter, you should be able to read map scales and identify common projections along with their basic features and uses.Scale and ways of telling the map user what the map is measuring on the ground.Projections deal with the methods and challenges around turning a three-dimensional (and sort of lumpy) earth into a two-dimensional map. Scale refers to how map units relate to real-world units. Scale and projections are two fundamental features of maps that usually do not get the attention they deserve. ![]()
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