The zones that have a predominant east-west orientation are mapped using the Lambert conformal conic map projections is that map projection minimizes distortion in the East and West directions.
The zones that have a prominent north-south orientation are mapped using the transverse Mercator map projection as that map projection minimizes distortion in the North and South directions.
This coordinate system uses the transverse Mercator projection with the central Meridian running through the center of each zone. The y-axis false origin is placed , m west of the zone central Meridian. The x-axis false origin for each zone is at the equator for North Hemisphere and 10,, m south of the equator for the southern hemisphere. Figure 60 is an illustration showing the universal transverse Mercator map projection. The zones are split into North and South about the equator.
Introduction to UTM 5 minute video. Stateplane Coordinate System 2 minute video. In this chapter you learned about distortions caused by map projections. You also learned about the tissot indicatrix which can be used to understand those distortions better. Authoring Organization: Del Mar College. Written by: Richard Smith. This workforce solution was funded by a grant awarded by the U. Department of Labor's Employment and Training Administration.
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Chapter 6 Part 3: Map Projection Distortions In this chapter you will learn about distortions caused by map projections. Figure Flat Polar Quartic Projection Equidistant Map Projection: On an equidistant map projection such as the equidistant cylindrical projection, where distances are true between two points, the circles are formed into different shapes throughout the map projection. Figure Equidistant Cylindrical Projection Aphylactic Map Projection: On an aphylactic map projection, which is another way of referring to a compromise map projection, we do not have perfect circles anywhere on the map; however, the distortion is not severe anywhere on the map.
Figure Robinson Projection 6. Recommended Map Projections for World Projections Equivalent: Equivalent map projections are recommended for world projections. Figure Mollweide Sinusoid: The sinusoid all map projection is also useful for mapping world distributions. Figure Sinusoid Aitoff- Hammer: The Aitoff-Hammer map projection is useful for mapping world distributions and excels at reducing the shape distortion at the extremities. Figure Goode's Homolosine Minimum Error: Minimum error map projections are also recommended for world projections.
Figure Robinson Winkel Tripel: The Winkle Tripel map projection is another good minimum error map projection choice when you want to map the entire world. Figure Winkel Tripel Cylindrical: Cylindrical map projections are recognized as a recommended map projection type for world projections. Chapter 7 - Typography. 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. If a map preserves shape, then shapes, such as outlines of countries, look the same on the map as they do on the earth. A map that preserves shape is called "conformal. If a map preserves area, then the size of a feature on the map is the same relative to its size on the earth. On an equal area map, if you draw a shape and move it around the map, no matter where you place it, its size will be the same.
If a map preserves distance, then a line between one point on the map and another is the same distance as it is on the earth taking scale into consideration.
Most maps have one or two lines of true scale. They mapped the coastline from their ships using what we might called primitive tools but it was amazing how accurate they were. Today we just pull up the latest satellite image, assuming that it has been rectified correctly and is fit for purpose. Know why you are producing the map, know why the data was captured. Take the time to bring out the cartographer in yourself. Save my name, email, and website in this browser for the next time I comment.
Join the team! Home Maps What four things do map projections distort? What four things do map projections distort?
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