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Fundamentals of GIS
Then, you can now state the scale as a representative fraction (RF): 0.04:10,000
Though it is a valid statement of scale, most cartographers may find it clumsy. Traditionally, the first number in the representative fraction is made equal to 1:
0.04 / 0.04 = 1 units on the map = 10,000 / 0.04 units on the ground
1 unit on the map = 250,000 units on the ground
Scale in Digital Maps
With digital maps, the traditional concept of scale in terms of distance does not apply because digital maps do not remain fixed in size. They can be displayed or plotted at any possible magnification. Yet we still speak of the scale of a digital map.
In digital mapping, the term scale is used to indicate the scale of the materials from which the map was made. For example, if a digital map is said to have a scale of 1:100,000, it was made from a 1:100,000-scale paper map.
However, a digital map's scale still allows you to make some educated guesses about its contents because, generally, digital maps retain the same accuracy and characteristics as their source maps. So it is still true that a large-scale digital map will usually be more accurate and less general than a small-scale digital map.
Because the display size of a computer-based map is not fixed, users are often tempted to blow up maps to very large sizes. For example, a 1:100,000-scale map can easily be plotted at a size of 1:24,000 or even 1:2,000-but it usually is not a good idea to do so. It encourages the user to make measurements that the underlying data does not support. You cannot measure positions to the nearest foot if your map is only accurate to the nearest mile. You will end up looking for information that does not exist.
Map Resolution
Map resolution refers to how accurately the location and shape of map features can be depicted for a given map scale. Scale affects resolution. In a larger-scale map, the resolution of features more closely matches real-world features because the extent of reduction from ground to map is less. As map scale decrease, the map resolution diminishes because features must be smoothed and simplified, or not shown at all.
Map Accuracy
Many factors besides resolution, influence how accurately features can be depicted, including the quality of source data, the map scale, your drafting skill and the width of lines drawn on the ground. A fine drafting pen will draw line's 1/100 of an inch wide. Such a line represents a corridor on the ground, which is almost 53 feet wide.
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