Understanding Map Projections

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ECKERT VI central meridian. Scale is correct only along these parallels. Nearer the poles, features are compressed in the north–south direction. LIMITATIONS Useful only as a world map. USES AND APPLICATIONS Suitable for thematic mapping of the world. The central meridian is 0°. Used for world distribution maps in the 1937 World Atlas by the Soviet Union. DESCRIPTION This equal-area projection is used primarily for world maps. PROJECTION METHOD A pseudocylindrical equal-area projection. LINEAR GRATICULES Parallels are unequally spaced straight lines. They are closer together at the poles. Meridians are equally spaced sinusoidal curves. The poles and the central meridian are straight lines half as long as the equator. PROPERTIES Shape Shapes are stretched north–south 29 percent along the equator, relative to the east–west dimension. This stretching decreases to zero at 49°16' N and S at the central meridian. Nearer the poles, features are compressed in the north–south direction. Area Equivalent. Direction Local angles are correct at the intersection of 49°16' N and S with the central meridian. Direction is distorted elsewhere. Distance Scale is distorted north–south 29 percent along the equator relative to the east–west dimension. This distortion decreases to zero at 49°16' N and S at the 52 • Understanding Map Projections
EQUIDISTANT CONIC Use the Equirectangular projection if the standard parallel is the equator. LINES OF CONTACT Depends on the number of standard parallels. Tangential projections (Type 1)—One line, indicated by the standard parallel. Secant projections (Type 2)—Two lines, specified as the first and second standard parallels. LINEAR GRATICULES All meridians. PROPERTIES The central meridian is 60° W. The first and second standard parallels are 5° S and 42° S. The latitude of origin is 32° S. DESCRIPTION This conic projection can be based on one or two standard parallels. As its name implies, all circular parallels are spaced evenly along the meridians. This is true whether one or two parallels are used as the standards. PROJECTION METHOD Cone is tangential if one standard parallel is specified and secant if two standard parallels are specified. Graticules are evenly spaced. Meridian spacing is equal, as is the space between each of the concentric arcs that describe the lines of latitude. The poles are represented as arcs rather than points. If the pole is given as the single standard parallel, the cone becomes a plane and the resulting projection is the same as a polar Azimuthal Equidistant. If two standard parallels are placed symmetrically north and south of the equator, the resulting projection is the same as the Equirectangular projection. In this case, you must use the Equirectangular projection. Shape Local shapes are true along the standard parallels. Distortion is constant along any given parallel but increases with distance from the standard parallels. Area Distortion is constant along any given parallel but increases with distance from the standard parallels. Direction Locally true along the standard parallels. Distance True along the meridians and the standard parallels. Scale is constant along any given parallel but changes from parallel to parallel. LIMITATIONS Range in latitude should be limited to 30 degrees. USES AND APPLICATIONS Regional mapping of midlatitude areas with a predominantly east–west extent. Common for atlas maps of small countries. Used by the former Soviet Union for mapping the entire country. Supported map projections• 53
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Understanding Map Projections GIS b
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Contents CHAPTER 1: GEOGRAPHIC COOR
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State Plane Coordinate System .....
Page 8 and 9: GEOGRAPHIC COORDINATE SYSTEMS A geo
Page 10 and 11: SPHEROIDS AND SPHERES The shape and
Page 12 and 13: DATUMS While a spheroid approximate
Page 15 and 16: 2 Projected coordinate systems Proj
Page 17 and 18: WHAT IS A MAP PROJECTION? Whether y
Page 19 and 20: PROJECTION TYPES Because maps are f
Page 21 and 22: maintained for both small-scale and
Page 23 and 24: Planar projections Planar projectio
Page 25 and 26: OTHER PROJECTIONS The projections d
Page 27: The four parameters above are used
Page 30 and 31: GEOGRAPHIC TRANSFORMATION METHODS M
Page 32 and 33: Unless explicitly stated, it’s im
Page 34 and 35: National Transformation version 2 L
Page 36 and 37: LIST OF SUPPORTED MAP PROJECTIONS A
Page 38 and 39: Loximuthal McBryde-Thomas Flat-Pola
Page 40 and 41: AITOFF USES AND APPLICATIONS Develo
Page 42 and 43: ALASKA SERIES E LIMITATIONS This pr
Page 44 and 45: AZIMUTHAL EQUIDISTANT Area Distorti
Page 46 and 47: BIPOLAR OBLIQUE CONFORMAL CONIC DES
Page 48 and 49: CASSINI-SOLDNER Area No distortion
Page 50 and 51: CRASTER PARABOLIC Distance Scale is
Page 52 and 53: DOUBLE STEREOGRAPHIC Oblique aspect
Page 54 and 55: ECKERT II The central meridian is 1
Page 56 and 57: ECKERT IV parallels. Nearer the pol
Page 60 and 61: EQUIDISTANT CYLINDRICAL LINES OF CO
Page 62 and 63: GALL’S STEREOGRAPHIC Area Area is
Page 64 and 65: GEOCENTRIC COORDINATE SYSTEM Geogra
Page 66 and 67: GNOMONIC PROPERTIES Shape Increasin
Page 68 and 69: HAMMER-AITOFF LIMITATIONS Useful on
Page 70 and 71: KROVAK Direction Local angles are a
Page 72 and 73: LAMBERT CONFORMAL CONIC Area Minima
Page 74 and 75: LOXIMUTHAL Distance Scale is true a
Page 76 and 77: MERCATOR Greenland is only one-eigh
Page 78 and 79: MOLLWEIDE Distance Scale is true al
Page 80 and 81: ORTHOGRAPHIC PROPERTIES Shape Minim
Page 82 and 83: PLATE CARRÉE Direction North, sout
Page 84 and 85: POLYCONIC Direction Local angles ar
Page 86 and 87: RECTIFIED SKEWED ORTHOMORPHIC DESCR
Page 88 and 89: SIMPLE CONIC Equirectangular projec
Page 90 and 91: SPACE OBLIQUE MERCATOR DESCRIPTION
Page 92 and 93: Montana—The three zones for Monta
Page 94 and 95: TIMES LIMITATIONS Useful only for w
Page 96 and 97: 10,000,000 meters to ensure that al
Page 98 and 99: UNIVERSAL POLAR STEREOGRAPHIC Area
Page 100 and 101: VAN DER GRINTEN I Distance Scale al
Page 102 and 103: WINKEL I Distance Generally, scale
Page 104 and 105: WINKEL T RIPEL Distance Generally,
Page 107 and 108: Glossary angular units The unit of
Page 109 and 110:
High Accuracy Reference Network A r
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UTM See Universal Transverse Mercat
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Eckert VI 52 ED 1950 6 Ellipse 101
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Projections (continued) planar 17,
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