The Azimuthal Equidistant preserves both distance and direction. The Winkel Tripel is a compromise projection. More about scale. Scale is the relationship between distance on a map or globe and distance on the earth. Suppose you have a globe that is 40 million times smaller than the earth. Its scale is ,, Any line you measure on this globe—no matter how long or in which direction—will be one forty -millionth as long as the corresponding line on the earth.
In other words, the scale is true everywhere. This is because the globe and the earth have the same shape disregarding the complication of sphere versus spheroid. Now suppose you have a flat map that is 40 million times smaller than the earth. See the problem coming? Instead of comparing a big orange to a little orange, we're comparing a big orange to a little wafer. This map also has a scale of ,,, but because the map and the earth are differently shaped, this scale cannot be true for every line on the map.
The stated scale of a map is true for certain lines only. Which lines these are depends on the projection and even on particular settings within a projection. We'll come back to this subject in Module 4, Understanding and Controlling Distortion. Not all of the earth's curves can be represented as straight lines at the same fixed scale. Some lines must be shortened and others lengthened. Expressing map scale There are three common ways to express map scale:.
Linear scales Linear scales are lines or bars drawn on a map with real-world distances marked on them. To determine the real-world size of a map feature, you measure it on the map with a ruler or a piece of string. Then you compare the feature's length on the string to the scale bar. A typical scale bar. Verbal scales Verbal scales are statements of equivalent distances.
For example, if a 4. Representative fractions Representative fractions express scale as a fraction or ratio of map distance to ground distance.
Since the scale is a ratio, it doesn't matter what the units are. Small scale and large scale maps It's easy to mix these terms up. Here's one way to keep them straight: on a large-scale map, the earth is large so not very much of it fits on the map. On a small-scale map, the earth is small so all or most of it fits on the map. A map of your town, or your property, is going to be a large-scale map.
A continental or world map is a small-scale map. Third, both kilometers and miles can be shown conveniently on the same bar scale. The scale bar should be subtle and it should not attract the attention of the map reader — instead they should have to shift their attention in order to find it on the page. Only use as many intermediate divisions are required. The scale bar should be thinner rather than thicker, and it should use thin lines for the bar and the ticks make sure you do this for all the lines that make up the scale bar including the ticks!
The font used to label the scale bar should be some of the smallest type of the page. Using more ticks than you need, thick lines, a wide scale bar and larger text unnecessarily complicates this map element and forces it to a higher level than it belongs in the visual hierarchy on the page. The optimal length of the scale bar is related to: 1 the amount of space on the page devoted to the map, and 2 the distances on the map that you expect the reader to measure. The scale bar should shorter than the map itself.
You can also design your scale bar to include an extension scale below which can be used for smaller distance determinations. Sometime you will see the extension scale to the left of the zero and sometimes it can be found as a greater umber of divisions to the right.
An extension scale which shows finer subdivisions of the scale bar allows for smaller distance measurements. The scale bar is usually placed below the map, but this will depend on your page layout. An advantage of placing the scale bar at the bottom of the page is that it serves as an anchoring element that ties the page space to the edge of the page.
If you have decided to use a scale bar and you have more than one mapped area e. If the map is to be used to determine distance relationships, then a scale bar is very useful to include. Most will include scale bars because route planning, navigation, and understanding about distances between places are common uses of reference maps. For , a scale bar should be used if distance determination can enhance the readers understanding of the theme shown.
If the theme does not have to do with distances, then a representative fraction can be used instead to indicate the amount of scale reduction that went into making the map. You usually do not need to include an extension scale on a scale bar for a thematic map — in fact, doing so may confuse the map reader because when they see it, they will wonder what they are supposed to be using it for.
For either reference or thematic maps, if you think the map will be enlarged or reduced, you should include a scale bar so that the scale indication will remain accurate. Variable scales, like the one illustrated above right, show how scale varies, in this case by latitude, due to deformation caused by map projection. Skip to main content.
Graphic Map Scales Print Another way to express map scale is with a graphic or "bar" scale. Figure 2. Map and Photo Scale up 6.
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