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@title{PROJ}{Projection Reference} @keyword{kernel projections parameter georeference segment set} @index{Projections} Why are projections needed for image processing? Projections are required to tie-down an image to the earth's surface. Once the required projection information has been defined and the image has been corrected to overlay the projection bounds, image equirectangular pixel and line coordinates can be transformed to produce equirectangular projection easting and northing coordinates which can be transformed with the projection formulas to produce equivalent non-equirectangular longitude and latitude coordinates. Or the inverse can be done: longitude and latitude coordinates can be transformed to projection easting and northings and image database pixel and line coordinates. Projections are useful to compensate for distortions in large-scale imagery that cover a large earth surface, where distortions are produced from earth curvature. These are the same distortions that occur in projecting a spherical surface (the earth) onto a flat surface (the image database). Although there are still distortions in all projections, some are removed or compensated for depending on the projection used. Once an image is tied to one projection, it can automatically be projected to overlay another projection. This gives you options to easily process your data, by matching your goals to the appropriate projection. The software used for the projection transforms is the GCTP (General Cartographic Transformation Package) produced by the U.S. Geological Survey (See the REFERENCES section.). It can be used to convert: - projection coordinates to geographic coordinates - geographic coordinates to projection coordinates - projection coordinates to coordinates in a second projection The conversions must use the same earth model (ellipsoid or sphere). The package is NOT meant to be used to convert between systems with different earth models. Transforming between projections with different earth models requires an actual geometric correction using a first-order affine transform (offsets and possibly scaling and rotation). Transforms between different earth models is discussed more under the EARTH_MODELS section in program REGPRO. 1 OUTPUT UNITS For supported projections, the output map units will take the following output format: 'proj 9999 r Ennn' Where: proj (Characters 1 to 4) is the standard string listed below for the projection. The string is left-justified. If the standard string is less than 4 characters the string is padded with trailing blanks. (e.g. 'UTM ') (Character 5 is blank) 9999 (Characters 6 to 9) is the zone number, if any. - for the UTM projection, depending on the value of the subroutine argument UTMROW, the zone number is returned right-justified in the range of ' 1' to ' 60' (or ' -1' to ' -60'). - for SPCS projections: '0101' to '5400' - for other projections: ' ' (Character 10 is blank) r (Character 11) is the UTM or UPS grid zone row, if any. For all other systems, this is blank. (Character 12 is blank) Ennn (Characters 13 to 16) Ellipsoid used for the projection - 'E000' to E019' for supported ellipsoids - Default is 'E000' if no earth model is defined in MAPUNITS or ELLIPS - 'E999' is a special case, where the earth model is not supported but was defined in ELLIPS 1 EARTH MODELS The following earth models are supported. Standard String Descriptor Notes E000 Clarke 1866 NAD1927 E001 Clarke 1880 E002 Bessel 1841 E003 New International 1967 E004 International 1924 Hayford 1909 E005 WGS 1972 E006 Everest 1830 E007 WGS 1966 E008 GRS 1980 NAD1983 E009 Airy 1830 E010 Modified Everest E011 Modified Airy E012 WGS 1984 GPS E013 Southeast Asia E014 Australian National 1965 E015 Krassovsky 1940 E016 Hough E017 Mercury 1960 E018 Modified Mercury 1968 E019 Sphere, rad 6370997 m Normal Sphere E999 Unsupported earth model, where the earth model fields are defined in an existing georeference segment. @pagebreak Semi-Major Semi-Minor Axis (A) Axis (B) ELLIPS Descriptor (metres) (metres) 0 Clarke 1866 6378206.400000 6356583.800000 1 Clarke 1880 6378249.145000 6356514.869550 2 Bessel 1841 6377397.155000 6356078.962840 3 New International 1967 6378157.500000 6356772.200000 4 International 1924 6378388.000000 6356911.946130 5 WGS 1972 6378135.000000 6356750.519915 6 Everest 1830 6377276.345200 6356075.413300 7 WGS 1966 6378145.000000 6356759.769356 8 GRS 1980 6378137.000000 6356752.314140 9 Airy 1830 6377563.396000 6356256.910000 10 Modified Everest 6377304.063000 6356103.039000 11 Modified Airy 6377340.189000 6356034.448000 12 WGS 1984 6378137.000000 6356752.314245 13 Southeast Asia 6378155.000000 6356773.320500 14 Australian Nat 1965 6378160.000000 6356774.719000 15 Krassovsky 1940 6378245.000000 6356863.018800 16 Hough 6378270.000000 6356794.343479 17 Mercury 1960 6378166.000000 6356784.283666 18 Modified Mercury 1968 6378150.000000 6356768.337303 19 Normal Sphere 6370997.000000 6370997.000000 As it stands, the U.S.G.S. GCTP software, that is used by EASI/PACE programs for conversions between projections, does not convert coordinates between different earth ellipsoids or datums. However there is software available to the public for conversion of NAD1927 coordinates to NAD1983 coordinates. For Canadian users, you can contact the following for the National Transformation package (Version 1.1): Geodetic Survey Division, 615 Booth Street, Ottawa, Ontario K1A 0E9 Tel: (613) 992-2706, (613) 995-2613 Fax: (613) 995-3215 The National Transformation package is also available through the Provincial Survey Agencies. For American users, you can contact the following for the NADCON package: National Geodetic Information Center, N/CG174, Rockwall Bldg., Room 24, National Geodetic Survey, NOAA, Rockville, Maryland 20852 Tel: (301) 443-8631 Fax: (301) 881-0154 1 UTM ZONES The Universal Transverse Mercator projection divides the earth into 60 UTM zones. Each zone is 6 degrees wide in longitude. The central meridian for the projection is in the middle of the UTM zone. (The reference latitude for all UTM zones is the equator.) UTM Zone Central UTM Zone Central Zone Range Meridian Zone Range Meridian 1 180W - 174W 177W 31 0E - 6E 3E 2 174W - 168W 171W 32 6E - 12E 9E 3 168W - 162W 165W 33 12E - 18E 15E 4 162W - 156W 159W 34 18E - 24E 21E 5 156W - 150W 153W 35 24E - 30E 27E 6 150W - 144W 147W 36 30E - 36E 33E 7 144W - 138W 141W 37 36E - 42E 39E 8 138W - 132W 135W 38 42E - 48E 45E 9 132W - 126W 129W 39 48E - 54E 51E 10 126W - 120W 123W 40 54E - 60E 57E 11 120W - 114W 117W 41 60E - 66E 63E 12 114W - 108W 111W 42 66E - 72E 69E 13 108W - 102W 105W 43 72E - 78E 75E 14 102W - 96W 99W 44 78E - 84E 81E 15 96W - 90W 93W 45 84E - 90E 87E 16 90W - 84W 87W 46 90E - 96E 93E 17 84W - 78W 81W 47 96E - 102E 99E 18 78W - 72W 75W 48 102E - 108E 105E 19 72W - 66W 69W 49 108E - 114E 111E 20 66W - 60W 63W 50 114E - 120E 117E 21 60W - 54W 57W 51 120E - 126E 123E 22 54W - 48W 51W 52 126E - 132E 129E 23 48W - 42W 45W 53 132E - 138E 135E 24 42W - 36W 39W 54 138E - 144E 141E 25 36W - 30W 33W 55 144E - 150E 147E 26 30W - 24W 27E 56 150E - 156E 153E 27 24W - 18W 21W 57 156E - 162E 159E 28 18W - 12W 15W 58 162E - 168E 165E 29 12W - 6W 9W 59 168E - 174E 171E 30 6W - 0E 3W 60 174E - 180W 177E 1 UTM GRID ZONES UTM zones divide the earth into columns, west to east. Each UTM zone can be divided into rows, south to north. If both the UTM zone and row are given, the area defined is referred to as a UTM grid zone. For example UTM30N is the area just west of Greenwich and just north of the equator. A UTM grid zone can be divided further. However within EASI/PACE, the row is only used to determine if the coordinates are north or south of the equator. If the UTM zone is defined and the row is not, the coordinates are assumed to be north of the equator. Coordinates north of the equator are assumed to have a false northing of 0.0 metres while coordinates south of the equator are assumed to have a false northing of 10000000.0 metres. UTM Row UTM Row Row Range Row Range C 80S - 72S N 0N - 8N D 72S - 64S P 8N - 16N E 64S - 56S Q 16N - 24N F 56S - 48S R 24N - 32N G 48S - 40S S 32N - 40N H 40S - 32S T 40N - 48N J 32S - 24S U 48N - 56N K 24S - 16S V 56N - 64N L 16S - 8S W 64N - 72N M 8S - 0N X 72N - 84N Note: - There is no row I or row O. - All rows are 8 degrees latitude, except row X which has 12 degrees latitude. - Grid zones A, B, Y, and Z exist, but are not valid for the UTM projection. They are used for the polar regions (A and B for the South Pole; Y and Z for the North Pole), which are mapped with the Universal Polar Stereographic (UPS) projection. 1 UPS GRID ZONES In the UPS grid system, which is used instead of UTM in the polar areas, each circular polar zone is divided in half by the the Prime Meridian (0 degrees Longitude) and 180 degrees Longitude (East or West). There are two grid zones over the North Pole (Y and Z) and two over the South Pole (A and B). A UPS grid zone can be divided further. However within EASI/PACE, the grid zone is only used to determine if the coordinates are at the North or South Pole. UPS Grid Zone Longitude Range Latitude Range A 180W - 0W 90S - 80S B 0E - 180E 90S - 80S Y 180W - 0W 84N - 90N Z 0E - 180E 84N - 90N Note: - Grid zones C to X (but not I or O) exist, but are not valid for the UPS projection. They are supported for the UTM projection. 1 SPCS ZONES The United States of America uses the State Plane Coordinate System as a system of plane rectangular coordinates that may be used for measuring ground distance and area. SPCS uses specified projections with set characteristics. In general, Transverse Mercator (TM) is used for States with predominant north-south extent and Lambert Conformal Conic (LCC) is used for States with predominant east-west extent. Other projections that may be used are Oblique Mercator (OM) in Alaska and Polyconic (PC) in Guam. The characteristics for each projection are stored in text files "nad1927.txt" and "nad1983.txt" that are provided in the $PCIHOME/etc subdirectory. The following is a list of codes for specifying State Plane zones. The "Zone Name or Number", "Alpha Code" and "Proj Type" are for your information and are NOT to be used to specify SPCS zones. The "zone unit code" is used instead. For example, to specify the zone for Alabama, East you would set MAPUNITS to "spaf 0101" (or "SPAF 101"). The "units" can be upper or lower-case. The "code" can have (but doesn't require) leading zeros. State Plane coordinates are only supported for NAD1927 (which uses Clarke 1866 ellipsoid) or NAD1983 (which uses the GRS 1980 ellipsoid). The units for a given zone will be derived from the units string typed in where: "SPAF" stands for "State Plane (U.S. Survey Feet)", where 1.0 inch of a "U.S. Survey Foot" equals APPROXIMATELY 25.4005 mm. (where 1.0 metre equals EXACTLY 39.37 inches) "SPIF" stands for "State Plane (International Foot)", where 1.0 inch of an "International Foot" equals EXACTLY 25.4 mm. "SPCS" stands for "State Plane (Metres)" For NAD27, the units are "SPAF" (i.e. "State Plane (U.S. Survey Feet)"). For NAD83, the units listed are those specified by State Laws as of February 1, 1992. Although these are the suggested units, they may be overridden. Any of the following work for the above example for NAD27. (The first example assumes NAD 1927, if no earth model is specified.) MAPUNITS="spaf 101" \ ELLIPS= \ MAPUNITS="spaf 101 e0" \ ELLIPS= \ MAPUNITS="spaf 101" \ ELLIPS="0" \ Any of the following work for the above example for NAD83. MAPUNITS="spaf 101 e8" \ ELLIPS= \ MAPUNITS="spaf 101" \ ELLIPS="8" \ The following list is copied from Appendix A of the U.S.G.S. "GCTP, General Cartographic Transformation Package Software Documentation". NAD27 NAD83 Alpha Proj zone zone Zone Name or Number code type unit code unit code Alabama AL East TM SPAF 0101 SPAF 0101 West TM SPAF 0102 SPAF 0102 Alaska AK 01 OM SPAF 5001 SPCS 5001 02 TM SPAF 5002 SPCS 5002 03 TM SPAF 5003 SPCS 5003 04 TM SPAF 5004 SPCS 5004 05 TM SPAF 5005 SPCS 5005 06 TM SPAF 5006 SPCS 5006 07 TM SPAF 5007 SPCS 5007 08 TM SPAF 5008 SPCS 5008 09 TM SPAF 5009 SPCS 5009 10 LCC SPAF 5010 SPCS 5010 Arizona AZ East TM SPAF 0201 SPIF 0201 Central TM SPAF 0202 SPIF 0202 West TM SPAF 0203 SPIF 0203 Arkansas AR North LCC SPAF 0301 SPAF 0301 South LCC SPAF 0302 SPAF 0302 California CA 01 LCC SPAF 0401 SPAF 0401 02 LCC SPAF 0402 SPAF 0402 03 LCC SPAF 0403 SPAF 0403 04 LCC SPAF 0404 SPAF 0404 05 LCC SPAF 0405 SPAF 0405 06 LCC SPAF 0406 SPAF 0406 07 LCC SPAF 0407 --------- Colorado CO North LCC SPAF 0501 SPIF 0501 Central LCC SPAF 0502 SPIF 0502 South LCC SPAF 0503 SPIF 0503 Connecticut CT LCC SPAF 0600 SPAF 0600 Delaware DE TM SPAF 0700 SPAF 0700 District of Columbia DC Use LCC SPAF 1900 SPAF 1900 Florida FL East TM SPAF 0901 SPAF 0901 West TM SPAF 0902 SPAF 0902 North LCC SPAF 0903 SPAF 0903 Georgia GA East TM SPAF 1001 SPCS 1001 West TM SPAF 1002 SPCS 1002 Hawaii HI 01 TM SPAF 5101 SPAF 5101 02 TM SPAF 5102 SPAF 5102 03 TM SPAF 5103 SPAF 5103 04 TM SPAF 5104 SPAF 5104 05 TM SPAF 5105 SPAF 5105 Idaho ID East TM SPAF 1101 SPAF 1101 Central TM SPAF 1102 SPAF 1102 West TM SPAF 1103 SPAF 1103 Illinois IL East TM SPAF 1201 SPAF 1201 West TM SPAF 1202 SPAF 1202 Indiana IN East TM SPAF 1301 SPAF 1301 West TM SPAF 1302 SPAF 1302 Iowa IA North LCC SPAF 1401 SPCS 1401 South LCC SPAF 1402 SPCS 1402 Kansas KS North LCC SPAF 1501 SPAF 1501 South LCC SPAF 1502 SPAF 1502 Kentucky KY North LCC SPAF 1601 SPAF 1601 South LCC SPAF 1602 SPAF 1602 Louisiana LA North LCC SPAF 1701 SPCS 1701 South LCC SPAF 1702 SPCS 1702 Offshore LCC SPAF 1703 SPCS 1703 Maine ME East TM SPAF 1801 SPCS 1801 West TM SPAF 1802 SPCS 1802 Maryland MD LCC SPAF 1900 SPAF 1900 Massachusetts MA Mainland LCC SPAF 2001 SPAF 2001 Island LCC SPAF 2002 SPAF 2002 Michigan MI East (Obsolete) TM SPAF 2101 --------- Central (Obsolete) TM SPAF 2102 --------- West (Obsolete) TM SPAF 2103 --------- North LCC SPAF 2111 SPIF 2111 Central LCC SPAF 2112 SPIF 2112 South LCC SPAF 2113 SPIF 2113 Minnesota MN North LCC SPAF 2201 SPCS 2201 Central LCC SPAF 2202 SPCS 2202 South LCC SPAF 2203 SPCS 2203 Mississippi MS East TM SPAF 2301 SPAF 2301 West TM SPAF 2302 SPAF 2302 Missouri MO East TM SPAF 2401 SPCS 2401 Central TM SPAF 2402 SPCS 2402 West TM SPAF 2403 SPCS 2403 Montana MT LCC --------- SPIF 2500 North LCC SPAF 2501 --------- Central LCC SPAF 2502 --------- South LCC SPAF 2503 --------- Nebraska NE LCC --------- SPAF 2600 North LCC SPAF 2601 --------- South LCC SPAF 2602 --------- Nevada NV East TM SPAF 2701 SPCS 2701 Central TM SPAF 2702 SPCS 2702 West TM SPAF 2703 SPCS 2703 New Hampshire NH TM SPAF 2800 SPCS 2800 New Jersey NJ TM SPAF 2900 SPCS 2900 New Mexico NM East TM SPAF 3001 SPAF 3001 Central TM SPAF 3002 SPAF 3002 West TM SPAF 3003 SPAF 3003 New York NY East TM SPAF 3101 SPAF 3101 Central TM SPAF 3102 SPAF 3102 West TM SPAF 3103 SPAF 3103 Long Island LCC SPAF 3104 SPAF 3104 North Carolina NC LCC SPAF 3200 SPAF 3200 North Dakota ND North LCC SPAF 3301 SPIF 3301 South LCC SPAF 3302 SPIF 3302 Ohio OH North LCC SPAF 3401 SPCS 3401 South LCC SPAF 3402 SPCS 3402 Oklahoma OK North LCC SPAF 3501 SPAF 3501 South LCC SPAF 3502 SPAF 3502 Oregon OR North LCC SPAF 3601 SPIF 3601 South LCC SPAF 3602 SPIF 3602 Pennsylvania PA North LCC SPAF 3701 SPCS 3701 South LCC SPAF 3702 SPCS 3702 Rhode Island RI TM SPAF 3800 SPCS 3800 South Carolina SC LCC --------- SPIF 3900 North LCC SPAF 3901 --------- South LCC SPAF 3902 --------- South Dakota SD North LCC SPAF 4001 SPCS 4001 South LCC SPAF 4002 SPCS 4002 Tennessee TN LCC SPAF 4100 SPAF 4100 Texas TX North LCC SPAF 4201 SPAF 4201 North Central LCC SPAF 4202 SPAF 4202 Central LCC SPAF 4203 SPAF 4203 South Central LCC SPAF 4204 SPAF 4204 South LCC SPAF 4205 SPAF 4205 Utah UT North LCC SPAF 4301 SPIF 4301 Central LCC SPAF 4302 SPIF 4302 South LCC SPAF 4303 SPIF 4303 Vermont VT TM SPAF 4400 SPCS 4400 Virginia VA North LCC SPAF 4501 SPCS 4501 South LCC SPAF 4502 SPCS 4502 Washington WA North LCC SPAF 4601 SPAF 4601 South LCC SPAF 4602 SPAF 4602 West Virginia WV North LCC SPAF 4701 SPCS 4701 South LCC SPAF 4702 SPCS 4702 Wisconsin WI North LCC SPAF 4801 SPAF 4801 Central LCC SPAF 4802 SPAF 4802 South LCC SPAF 4803 SPAF 4803 Wyoming WY East (01) TM SPAF 4901 SPCS 4901 East Central (02) TM SPAF 4902 SPCS 4902 West Central (03) TM SPAF 4903 SPCS 4903 West (04) TM SPAF 4904 SPCS 4904 Puerto Rico PR LCC SPAF 5201 SPCS 5200 Virgin Islands VI LCC SPAF 5201 SPCS 5200 St. Croix LCC SPAF 5202 SPCS 5200 American Samoa AS LCC SPAF 5300 --------- Guam GU PC SPAF 5400 --------- See Also: {|PROJECTIONS|}SPCS 1 PROJECTIONS The following are a list of the supported projections and their required input. Projections are usually categorized by the type of the surface the earth is projected onto: - cylindrical, where the projection is a cylinder wrapped around the globe (e.g. Mercator projection). - conic, where the projection is a cone placed over the globe (e.g. Lambert Conformal Conic projection). - azimuthal, where the globe is projected onto a plane (e.g. Stereographic projection). Other projections may be formed by modifying the basic types (e.g. pseudo-cylindrical). The projection type is listed below as the "General class" for the projection. In projecting a sphere (the earth) to a surface (the image), the geometry of the sphere is changed. A given projection usually retains some characteristics of the sphere, usually at the expense of other characteristics. The following terms are listed below as "Characteristics" for the projections where: - Equal-area implies a feature on one part of the map would cover the same area, if it also occurred on any other part of the map. - Conformal implies "correct form or shape". Actually it infers the relative local angles about every point of the map as being shown correctly. This only applies to smaller, local areas. All projections distort shape for larger areas. - Equidistant projections show true scale between one point (or two points) and every other point on the map. - Rectangular coordinates mean that the grid of the projection can be used to approximate distances, directions and areas of the earth surface. Rectangular coordinates are also referred to as plane coordinates. The earth model for the projection may be defined in the MAPUNITS string or in the ELLIPS parameter. (See the EARTH_MODELS section.) Some projections can process the earth as an ellipsoid or a sphere, while some only process the earth as a sphere. This is noted for the projection as the "Earth model:" using an "ellipsoid or sphere" or "sphere". This is important if the earth model is not supported and is defined as values in the ELLIPS parameter: - For projections that use an "ellipsoid or sphere", ELLIPS may be a. the semi-major axis (or equatorial radius or A) for the earth b. the semi-minor axis (or polar radius or B) or the eccentricity squared. If the unsupported earth model is a sphere, this could be defined in either of the following ways: - do not specify a second value (i.e. only one radius is defined). - specify the equatorial radius again (i.e. the polar radius equals the equatorial radius). - specify the second value as zero (i.e. the eccentricity squared is zero). In general, non-azimuthal projections (i.e. cylindrical or conic) usually use an "ellipsoid or sphere". If no earth model is defined for a projection that uses an "ellipsoid or sphere", the earth model ellipsoid defaults to E000 (i.e. Clarke 1866 or NAD 1927). Projections that use a "sphere", will use the first value in ELLIPS as the radius of the earth. If there is a second value defined, it is ignored. Azimuthal projections usually use a "sphere", but not an ellipsoid. If no earth model is defined for projections that use a "sphere", the default will be E019 (i.e. Normal Sphere of 6370997 metres). The fields required for each projection are listed. Any parameters not mentioned are not used for the projection. Possible errors are listed for each projection. In general any of the projections will exit with E333 ("Projection was not initialized"), if the required parameters for the projection were not specified. 2 ACEA Projection : Albers Conical Equal Area General class : conic Characteristics: equal-area Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "acea" | Standard name. EASI>mapunits = "acea e0" | Standard name and the ellipsoid. Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>stpar1 = "1st_standard_parallel" | Required EASI>stpar2 = "2nd_standard_parallel" | Required EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E332, "Equal latitudes for st. parallels on opposite sides of equator" - Error encountered in initializing for the projection. 2 AE Projection : Azimuthal Equidistant General class : azimuthal Characteristics: neither equal-area nor conformal Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "ae" | Standard name EASI>mapunits = "ae e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E335, "Point projects into a circle" - In converting from geographic coordinates to projection coordinates, the point projects into a circle. E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 EC Projection : Equidistant Conic General class : conic Characteristics: equidistant Earth model : ellipsoid or sphere Defining the MAPUNITS (Format A or B): EASI>mapunits = "ec" | Standard name EASI>mapunits = "ec e0" | Standard name and ellipsoid Other parameters (Format A, one standard parallel): EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>stpar1 = "1st_standard_parallel" | Required EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Other parameters (Format B, two standard parallels): EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>stpar1 = "1st_standard_parallel" | Required EASI>stpar2 = "2nd_standard_parallel" | Required EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E332, "Equal latitudes for st. parallels on opposite sides of equator " - Error occurred in initializing the projection. 2 ER Projection : Equirectangular (Plate Carree) General class : cylindrical Characteristics: neither equal-area nor conformal Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "er" | Standard name EASI>mapunits = "er e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_true_scale" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 GNO Projection : Gnomonic General class : azimuthal Characteristics: neither conformal nor equal-area Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "gno" | Standard name EASI>mapunits = "gno e19" | Standard name and ellipsoid EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point projects into infinity 2 GVNP Projection : General Vertical Near-Side Perspective General class : azimuthal Characteristics: neither conformal nor equal-area Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "gvnp" | Standard name EASI>mapunits = "gvnp e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero EASI>pheight = "height_of_perspective" | Usually defined, | if defaulted is zero Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point cannot be projected. E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 LAEA Projection : Lambert Azimuthal Equal-Area General class : azimuthal Characteristics: equal-area Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "laea" | Standard name EASI>mapunits = "laea e19" | Standard name and ellipsid Other parameters: EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E335, "Point projects into a circle" - In converting from geographic coordinates to projection coordinates, the point projects into a circle. E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 LCC Projection : Lambert Conformal Conic General class : conic Characteristics: conformal : rectangular coordinates (U.S.A.; France) Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "lcc" | Standard name EASI>mapunits = "lcc e0" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>stpar1 = "1st_standard_parallel" | Required EASI>stpar2 = "2nd_standard_parallel" | Required EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E332, "Equal latitudes for st. parallels on opposite sides of equator" - Error occurred in initializing the projection E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point projects into infinity 2 LONG/LAT Geographic coordinates (not a projection). Earth model: ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits="long/lat" | Standard name. Synonyms: "lon", | "lat", "lat/long" or "geo" Other parameters: None Note: If a bounds is defined, it must be in geographic coordinates (i.e. LONG1, LAT1, LONG2, LAT2) as there is no projection to convert from or to. 2 MC Projection : Miller Cylindrical General class : cylindrical Characteristics: neither equal-area nor conformal Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "mc" | Standard name EASI>mapunits = "mc e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required --+- True origin EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero 2 MER Projection : Mercator General class : cylindrical Characteristics: conformal Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "mer" | Standard name EASI>mapunits = "mer e0" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_true_scale" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the transform cannot be computed at the poles. 2 MSC Projection : Modified Stereographic Conformal General class : modified azimuthal Characteristics: conformal Earth model : only Clarke 1866 (NAD 1927) Defining the MAPUNITS: EASI>mapunits = "msc" | Standard name Other parameters: EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E330, "Calculation failed to converge to a solution" - In converting from projection coordinates to geographic coordinates, too many iterations were made. 2 OG Projection : Orthographic General class : azimuthal Characteristics: neither conformal nor equal-area Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "og" | Standard name. EASI>mapunits = "og e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point cannot be projected. E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 OM Projection : Oblique Mercator (Hotine) General class : cylindrical Characteristics: conformal Earth model : ellipsoid or sphere Defining the MAPUNITS (Format A or B): EASI>mapunits = "om" | Standard name EASI>mapunits = "om e0" | Standard name and ellipsoid Other parameters (Format A): EASI>prolat = "latitude_of_origin" | Required --- True origin EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero EASI>scale = "scale_at_center" | Optional, default is one EASI>long1 = "longitude_central_line" | Required EASI>lat1 = "latitude_central_line" | Required EASI>long2 = "longitude_central_line" | Required EASI>lat2 = "latitude_central_line" | Required Other parameters (Format B): EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero EASI>scale = "scale_at_center" | Optional, default is one EASI>azimuth = "azimuth" | Required, azimuth east of | north for central line Possible errors: E100, "Invalid data" - In initializing for the projection, there was an input data error E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point projects into infinity 2 PC Projection : Polyconic General class : conic Characteristics: neither conformal nor equal-area Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "pc" | Standard name EASI>mapunits = "pc e0" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero 2 PS Projection : Polar Stereographic General class : azimuthal Characteristics: conformal Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "ps" | Standard name EASI>mapunits = "ps e0" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_true_scale" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero 2 ROB Projection : Robinson General class : pseudo-cylindrical Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "rob" | Standard name EASI>mapunits = "rob e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required --- True origin EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E330, "Calculation failed to converge to a solution" - In converting from projection coordinates to geographic coordinates, too many iterations were made. 2 SG Projection : Stereographic General class : azimuthal Characteristics: conformal Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "sg" | Standard name EASI>mapunits = "sg e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "longitude_of_origin" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point projects into infinity 2 SIN Projection : Sinusoidal General class : pseudo-cylindrical Characteristics: equal-area Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "sin" | Standard name EASI>mapunits = "sin e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "longitude_of_origin" | Required --- True origin EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E100, "Invalid data" - In converting from projection coordinates to geographic coordinates, there was an input data error 2 SOM Projection : Space Oblique Mercator General class : modified cylindrical Characteristics: basically conformal Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "som" | Standard name EASI>mapunits = "som e0" | Standard name and ellipsoid Other parameters: EASI>lsatnum = "landsat_number" | Required EASI>pathnum = "path_number" | Required EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero Possible errors: E100, "Invalid data" - In initializing for the projection, the Landsat satellite number and/or path number are out of range. E330, "Calculation failed to converge to a solution" - In converting from projection coordinates to geographic coordinates, too many iterations were made. 2 SPCS Projection : State Plane Coordinate System Characteristics: rectangular coordinates Earth model: Only two earth models are supported for State Plane coordinates: - E0, Clarke 1866 (NAD 1927) - E8, GRS 1980 (NAD 1983) These may be defined in the MAPUNITS parameter or the ELLIPS parameter. If undefined, the default earth model is E0 (Clarke 1866, NAD 1927). Any other earth models will be treated as an error. Defining the MAPUNITS: State Plane Coordinate System coordinates require a zone number to be defined. This would be defined in the MAPUNITS parameter and would be in the range of 0101 (or 101 for Alabama, East in the following examples) to 5400 (Guam). See the SPCS_ZONES section for a list of the State Plane Zones. EASI>mapunits = "spcs 101" | Standard name EASI>mapunits = "spcs 101 e0" | Standard name and ellipsoid Other parameters: Depending on the defined (or default) earth model, PROSET will require a text file that is normally stored in /pci/etc on UNIX platforms. (The search path may be different, depending on the platform.) If these files are there, the NAD1927 and/or NAD1983 parameters may be defaulted, in which case PROSET should be able to find them. (PROSET uses the WDFF parameter, substituting "etc" for "wdb" (or "ETC" for "WDB"), to make up the search path.) If the pci account is not in for example /pci the text files would not be found and the program would exit. In any case the search path and filename can be explicitly defined with the NAD1927 and NAD1983 parameters. EASI>nad1927 = "nad1927_text_file" EASI>nad1983 = "nad1983_text_file" Possible errors: E331, "Invalid earth model defined for the projection" - In setting up for the projection, the earth model is not E0 (Clarke 1866, NAD 1927) or E8 (GRS 1980, NAD 1983). E100, "Invalid data" - In setting up for the projection, an invalid State Plane zone was entered. E328, "No zone was defined or could be derived for the projection" - In setting up for the projection, the State Plane zone was not specified in MAPUNITS. See Also: {|}SPCS ZONES 2 TM Projection : Transverse Mercator (Gauss-Krueger) General class : cylindrical Characteristics: conformal : rectangular coordinates (U.S.A.; Britain) Earth model : ellipsoid or sphere Defining the MAPUNITS: EASI>mapunits = "tm" | Standard name EASI>mapunits = "tm e0" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required -+- True origin EASI>prolat = "latitude_of_origin" | Required / EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero EASI>scale = "scale_at_cent_meridian" | Optional, default is one Possible errors: E334, "Point cannot be projected" - In converting from geographic coordinates to projection coordinates, the point projects into infinity E330, "Calculation failed to converge to a solution" - In converting from projection coordinates to geographic coordinates, the conversion failed to converge to a solution @pagebreak 2 UPS Projection : Universal Polar Stereographic General class : azimuthal Characteristics: conformal : rectangular coordinates Earth model : only supported ellipsoids or spheres (i.e. E000 to E019) Universal Polar Stereographic projection requires a zone to be specified or a sample point in geographic coordinates from which a zone can be derived. If a zone is specified it would be in the MAPUNITS string. Any of the following are valid: Defining the MAPUNITS: EASI>mapunits="ups z" | Standard name and zone EASI>mapunits="ups z e0" | Standard name, zone, and ellipsoid If the zone is not defined in the MAPUNITS string, a sample point can be input with PROLONG and PROLAT. For example: EASI>mapunits = "ups" EASI>prolong = "117 w" EASI>prolat = " 84 n" If the UPS zone, PROLONG and PROLAT are not defined, but (BX1 and BY1) or (BX2 and BY2) define 'LONG/LAT' point(s), one of these can be used to derive the UPS zone. (If both (BX1 and BY1) and (BX2 and BY2) are defined, (BX1 and BY1) is used.) If the UPS zone is derived from a sample point and the longitude for the point is shared between zones, the eastern-most zone is returned. For example, if prolong="0 w" and prolat="84 n", the assumed zone is UPS zone Z, not UPS zone Y. Any confusion can be avoided, by picking a sample point in the zone and not on the zone border. Other parameters: None Possible errors: E331, "Invalid earth model defined for the projection" - In setting up for the projection, the earth model is not in the range of E0 to E19 and is defined explicitly with the ELLIPS parameter. E108, "Option not available" - In setting up for the projection, the UPS zone is not A, B, Y or Z. 2 UTM Projection : Universal Transverse Mercator General class : cylindrical Characteristics: conformal : rectangular coordinates Earth model : only supported ellipsoids or spheres (i.e. E000 to E019) Universal Transverse Mercator projection requires a zone to be specified or a sample point in geographic coordinates from which a zone can be derived. Once the zone is known, the central meridian can be derived for the zone. If a zone is specified it would be in MAPUNITS string. Any of the following are valid: Defining the MAPUNITS: EASI>mapunits="utm 11" | Standard name and zone EASI>mapunits="utm 11 m" | Standard name, zone and row EASI>mapunits="utm 11 m e0" | Standard name, zone, row and ellipsoid If the zone is not defined in the MAPUNITS string, a sample point can be input with PROLONG and PROLAT. For example: EASI>mapunits = "utm" EASI>prolong = "117 w" EASI>prolat = " 33 n" If the UTM zone, PROLONG and PROLAT are not defined, but (BX1 and BY1) or (BX2 and BY2) define 'LONG/LAT' point(s), one of these can be used to derive the UTM zone. (If both (BX1 and BY1) and (BX2 and BY2) are defined, (BX1 and BY1) is used.) If the UTM zone is derived from a sample point and the longitude for the point is shared between zones, the eastern-most zone is returned. For example, if prolong="174w", the assumed zone is UTM zone 2, not UTM zone 1. Any confusion can be avoided, by picking a sample point in the zone and not on the zone border. Other parameters: None Possible errors: E331, "Invalid earth model defined for the projection" - In setting up for the projection, the earth model is not in the range of E0 to E19 and is defined explicitly with the ELLIPS parameter. E309, "Range mistake (might be syntax or range)" - In setting up for the projection, the UTM zone is outside the range of 1 to 60 E328, "No zone was defined or could be derived for the projection" - In setting up for the projection, the UTM zone was not specified in MAPUNITS. 2 VDG Projection : Van der Grinten General class : miscellaneous Characteristics: neither equal-area nor conformal Earth model : sphere Defining the MAPUNITS: EASI>mapunits = "vdg" | Standard name EASI>mapunits = "vdg e19" | Standard name and ellipsoid Other parameters: EASI>prolong = "central_meridian" | Required --- True origin EASI>efalse = "false_easting" | Optional, default is zero EASI>nfalse = "false_northing" | Optional, default is zero 1 REFERENCES Robinson, A.H., Sale, R.D., Morrison, J.L., and Muehrcke, P.C., "Elements of Cartography (5th Ed.)", John Wiley and Sons, New York, 1984. Snyder, John P., "Map Projections - A Working Manual", U.S.G.S. Professional Paper 1395, U.S. Geological Survey, Reston, Virginia, 1987. "Software Documentation for GCTP, General Cartographic Transformation Package", U.S. Geological Survey, National Mapping Division, Reston, Virginia, 1990 (Unpublished).