Understanding Map Projections

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KROVAK Direction Local angles are accurate throughout because of conformality. Distance Minimal distortion within the boundaries of the countries. LIMITATIONS Designed strictly for Czech Republic and Slovakia. This example of the Krovak projection uses a right-handed coordinate system. USES AND APPLICATIONS Used for topographic and other mapping in Czech Republic and Slovakia. The coordinates are usually positive to the south and west. DESCRIPTION This projection is an oblique case of the Lambert conformal conic projection and was designed in 1922 by Josef Krovak. Used in the Czech Republic and Slovakia. Also known as S-JTSK. PROJECTION METHOD Conic projection based on one standard parallel. An azimuth parameter tilts the apex of the cone from the North Pole to create a new coordinate system. A standard parallel in the new system, called a pseudostandard parallel, defines the shape of the cone. A scale factor is applied to the pseudo-standard parallel to create a secant case. LINES OF CONTACT Two pseudo-standard parallels. LINEAR GRATICULES None. PROPERTIES Shape Small shapes are maintained. Area Minimal distortion within the boundaries of the countries. 64 • Understanding Map Projections
LAMBERT AZIMUTHAL EQUAL AREA PROPERTIES Shape Shape is minimally distorted, less than 2 percent, within 15 degrees from the focal point. Beyond that, angular distortion is more significant; small shapes are compressed radially from the center and elongated perpendicularly. Area Equal area. Direction True direction radiating from the central point. The central meridian is 0°, and the latitude of origin is 90° S. DESCRIPTION This projection preserves the area of individual polygons while simultaneously maintaining a true sense of direction from the center. The general pattern of distortion is radial. It is best suited for individual land masses that are symmetrically proportioned, either round or square. PROJECTION METHOD Planar, projected from any point on the globe. This projection can accommodate all aspects: equatorial, polar, and oblique. POINT OF TANGENCY A single point, located anywhere, specified by longitude and latitude. LINEAR GRATICULES All aspects—The central meridian defining the point of tangency. Distance True at center. Scale decreases with distance from the center along the radii and increases from the center perpendicularly to the radii. LIMITATIONS The data must be less than a hemisphere in extent. The software cannot process any area more than 90 degrees from the central point. USES AND APPLICATIONS Population density (area). Political boundaries (area). Oceanic mapping for energy, minerals, geology, and tectonics (direction). This projection can handle large areas; thus it is used for displaying entire continents and polar regions. Equatorial aspect Africa, Southeast Asia, Australia, the Caribbeans, and Central America Oblique aspect North America, Europe, and Asia Equatorial aspect—The equator. Polar aspect—All meridians. Supported map projections• 65
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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 .....
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GEOGRAPHIC COORDINATE SYSTEMS A geo
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SPHEROIDS AND SPHERES The shape and
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DATUMS While a spheroid approximate
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2 Projected coordinate systems Proj
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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 58 and 59: ECKERT VI central meridian. Scale i
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 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
Page 111: UTM See Universal Transverse Mercat
Page 114 and 115: Eckert VI 52 ED 1950 6 Ellipse 101
Page 116: Projections (continued) planar 17,
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