Changes between Version 1 and Version 2 of Cf2CrsWkt


Ignore:
Timestamp:
03/06/12 15:03:53 (8 years ago)
Author:
etourigny
Comment:

--

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  • Cf2CrsWkt

    v1 v2  
    1 = Mapping from CF Grid Mapping Attributes to CRS WKT Elements =
     1= CF-1.6 <--> WKT/PROJ.4 translation =
     2
     3== Mapping from CF Grid Mapping Attributes to CRS WKT Elements ==
     4
     5These ''provisional'' mappings have been compiled to support, among other things, CF proposals [ticket:69] and [ticket:x].
     6If you spot any errors or omissions, please email the authors (Phil Bentley and Etienne Tourigny) or the CF mailing list, or else update this wiki page.
     7
     8In Tables 1 and 2 the names of WKT PARAMETER elements follow the names of coordinate operation parameters
     9defined in the [http://www.epsg-registry.org/ EPSG geodetic parameter registry].
     10
     11The following tables list translations of projection parameter names between CF and various other representations (such as OGC WKT, EPSG and PROJ.4). The information was obtained from various sources, including http://www.remotesensing.org/geotiff/proj_list/ .
     12
     13The various representations listed are:
     14
     15 * '''CF''' The CF-1.6 (and possibly CF-1.7) parameter names
     16 * '''OGC WKT''' The names following OGC WKT specification (used by GDAL/OGR and CadCorp)
     17 * '''PROJ.4''' The names used in the PROJ.4 software (http://trac.osgeo.org/proj/)
     18 * '''EPSG''' The names and codes used in the EPSG Geodetic Parameter Dataset (http://www.epsg.org/ and http://www.epsg-registry.org/)
     19 * '''GeoTIFF ID''' The names used in the GeoTIFF raster format (http://trac.osgeo.org/geotiff/)
     20
     21=== Table 1 - Existing (CF-1.6) CF Grid Mapping Attributes ===
     22|| '''CF Grid Mapping Attribute''' || '''Corresponding WKT Syntax''' (1) ||
     23|| `earth_radius` || `SPHEROID["<reference_ellipsoid_name>", <semi_major_axis>, 0.0, ...]` ||
     24|| `false_easting` || `PARAMETER["False easting", <value>]` ||
     25|| `false_northing` || `PARAMETER["False northing", <value>]` ||
     26|| `grid_mapping_name` || no known equivalent ||
     27|| `grid_north_pole_latitude` || no known equivalent ||
     28|| `grid_north_pole_longitude` || no known equivalent ||
     29|| `inverse_flattening` || `SPHEROID["<reference_ellipsoid_name>", <semi_major_axis>, <inverse_flattening>, ...]` ||
     30|| `latitude_of_projection_origin` || `PARAMETER["Latitude of natural origin", <value>]` ||
     31|| `longitude_of_central_meridian` || `PARAMETER["Longitude of natural origin", <value>]` ||
     32|| `longitude_of_prime_meridian` || `PRIMEM["<prime_meridian_name>", <longitude_of_prime_meridian>, ...]` ||
     33|| `longitude_of_projection_origin` || `PARAMETER["Longitude of natural origin", <value>]` ||
     34|| `north_pole_grid_longitude` || no known equivalent ||
     35|| `perspective_point_height` || `PARAMETER["Viewpoint height", <value>]` ||
     36|| `scale_factor_at_central_meridian` || `PARAMETER["Scale factor at natural origin", <value>]` ||
     37|| `scale_factor_at_projection_origin` || `PARAMETER["Scale factor at natural origin", <value>]` ||
     38|| `semi_major_axis` || `SPHEROID["<reference_ellipsoid_name>", <semi_major_axis>, <inverse_flattening>, ...]` ||
     39|| `semi_minor_axis` || no direct equivalent, the `SPHEROID` element is used to define ellipsoid geometry ||
     40|| `standard_parallel` (one parallel) || `PARAMETER["Latitude of standard parallel", <value>]` ||
     41|| `standard_parallel` (two parallels) || `PARAMETER["Latitude of 1st standard parallel", <value>], PARAMETER["Latitude of 2nd standard parallel", <value>]` ||
     42|| `straight_vertical_longitude_from_pole` || `PARAMETER["Longitude of origin", <value>]` ||
     43
     44=== Table 2 - Future (CF-1.7) CF Grid Mapping Attributes ===
     45
     46|| '''CF Grid Mapping Attribute''' || '''Corresponding WKT Syntax''' (1) ||
     47|| `projected_coordinate_system_name` || `PROJCS["<projected_coordinate_system_name>", ...]` ||
     48|| `geographic_coordinate_system_name` || `GEOGCS["<geographic_coordinate_system_name>", ...]` ||
     49|| `horizontal_datum_name` || `GEOGCS["<name>", DATUM["<horizontal_datum_name>", ...] ]` ||
     50|| `reference_ellipsoid_name` || `GEOGCS["<name>", DATUM["<name>", SPHEROID["<reference_ellipsoid_name>", ...] ] ]` ||
     51|| `towgs84` || `GEOGCS["<name>", DATUM["<name>", TOWGS84[<7 params>] ]` ||
     52|| `prime_meridian_name` || `GEOGCS["<name>",PRIMEM["<prime_meridian_name>",<value>]` ||
     53
     54
     55=== Table 3 - Coordinate system keywords in CF-1.7/WKT/PROJ.4 ===
     56
     57||'''CF'''||'''OGC WKT'''||'''PROJ.4'''||'''Note'''||
     58|| || || || ||
     59||projected_coordinate_system_name||PROJCS||N/A|| ||
     60||geographic_coordinate_system_name||GEOGCS||N/A|| ||
     61||horizontal_datum_name||GEOGCS|DATUM||+datum|| ||
     62||reference_ellipsoid_name||GEOGCS|DATUM|SPHEROID||+ellps|| ||
     63||towgs84||GEOGCS|DATUM|TOWGS84||+towgs84|| ||
     64||prime_meridian_name||GEOGCS|PRIMEM||+pm|| ||
     65
     66=== Table 4 - Common projection parameter names ===
     67
     68||'''CF'''||'''OGC WKT'''||'''PROJ.4'''||'''EPSG name'''||'''Note'''||
     69|| || || || || ||
     70||false_easting||false_easting||+x_0||False easting / Easting at false origin||(2)||
     71||false_northing||false_northing||+y_0||False northing / Northing at false origin||(2)||
     72||scale_factor_at_projection_origin||scale_factor||+k_0||Scale factor at natural origin||(1)||
     73||scale_factor_at_central_meridian||scale_factor||+k_0||Scale factor at natural origin||(1)||
     74||standard_parallel![1]||standard_parallel_1||+lat_1||Latitude of 1st standard parallel|| ||
     75||standard_parallel![2]||standard_parallel_2||+lat_2||Latitude of 2nd standard parallel|| ||
     76||longitude_of_central_meridian||longitude_of_center / central_meridian||+lon_0||(1)||(1)||
     77||longitude_of_projection_origin||longitude_of_center / central_meridian||+lon_0||(1)||(1)||
     78||latitude_of_projection_origin||latitude_of_origin / latitude_of_center||+lat_0||(1)||(1)||
     79||straight_vertical_longitude_from_pole||central_meridian||+lon_0||(1)||(1)||
     80
     81=== Table 5 - Specific projection parameter names ===
     82
     83||'''Projection'''||'''Name'''||'''CF'''||'''OGC WKT'''||'''PROJ.4'''||'''EPSG name'''||'''EPSG code'''||'''GeoTIFF ID'''||'''Note'''||
     84|| || || || || || || || || ||
     85||'''AEA'''||Albers Equal Area||albers_conical_equal_area||Albers_Conic_Equal_Area||+proj=aea||Albers Equal Area||9822||CT_AlbersEqualArea|| ||
     86|| || ||standard_parallel![1]||standard_parallel_1||+lat_1||Latitude of 1st standard parallel||8823||!StdParallel1|| ||
     87|| || ||standard_parallel![2]||standard_parallel_2||+lat_2||Latitude of 2nd standard parallel||8824||!StdParallel2|| ||
     88|| || ||longitude_of_central_meridian||longitude_of_center||+lon_0||Longitude of false origin||8822||!NatOriginLong|| ||
     89|| || ||latitude_of_projection_origin||latitude_of_center||+lat_0||Latitude of false origin||8821||!NatOriginLat|| ||
     90||||||false_easting||false_easting||+x_0||Easting at false origin||8826||!FalseEasting||||
     91||||||false_northing||false_northing||+y_0||Northing at false origin||8827||!FalseNorthing||||
     92|| || || || || || || || || ||
     93||'''AE'''||Azimuthal equidistant||azimuthal_equidistant||Azimuthal_Equidistant||+proj=aeqd||N/A||||CT_AzimuthalEquidistant ||EPSG:9832 is 'Modified Azimuthal Equidistant'||
     94|| || ||longitude_of_projection_origin||longitude_of_center||+lon_0|||| ||!ProjCenterLong|| ||
     95|| || ||latitude_of_projection_origin||latitude_of_center||+lat_0|||| ||!ProjCenterLat|| ||
     96||||||false_easting||false_easting||+x_0||||||!FalseEasting||||
     97||||||false_northing||false_northing||+y_0||||||!FalseNorthing||||
     98|| || || || || || || || || ||
     99||'''LAEA'''||Lambert azimuthal equal area||lambert_azimuthal_equal_area||Lambert_Azimuthal_Equal_Area||+proj=laea||Lambert Azimuthal Equal Area||9820||CT_LambertAzimEqualArea || ||
     100|| || ||longitude_of_projection_origin||longitude_of_center||+lon_0||Longitude of natural origin||8802||!ProjCenterLong|| ||
     101|| || ||latitude_of_projection_origin||latitude_of_center||+lat_0||Latitude of natural origin||8801||!ProjCenterLat|| ||
     102||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     103||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     104|| || || || || || || || || ||
     105||'''LCC-1SP'''||Lambert conformal||lambert_conformal_conic||Lambert_Conformal_Conic_1SP||+proj=lcc||Lambert Conic Conformal (1SP)||9801||CT_LambertConfConic_1SP||(3) [http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_1sp.html link]||
     106|| || ||standard_parallel||latitude_of_origin||+lat_1||Latitude of natural origin||8801||!NatOriginLat||standard_parallel=latitude_of_projection_origin||
     107|| || ||longitude_of_central_meridian||central_meridian||+lon_0||Longitude of natural origin||8802||!NatOriginLong|| ||
     108|| || ||latitude_of_projection_origin||latitude_of_origin||+lat_0||Latitude of natural origin||8801||!NatOriginLat|| ||
     109|| || ||N/A||scale_factor||+k_0||Scale factor at natural origin||8805||!ScaleAtNatOrigin||(3) always 1||
     110||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     111||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     112|| || || || || || || || || ||
     113||'''LCC-2SP'''||Lambert conformal||lambert_conformal_conic||Lambert_Conformal_Conic_2SP||+proj=lcc||Lambert Conic Conformal (2SP)||9802||CT_LambertConfConic_2SP ||(3) [http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_2sp.html link]||
     114|| || ||standard_parallel![1]||standard_parallel_1||+lat_1||Latitude of 1st standard parallel||8823||!StdParallel1|| ||
     115|| || ||standard_parallel![2]||standard_parallel_2||+lat_2||Latitude of 2nd standard parallel||8824||!StdParallel2|| ||
     116|| || ||longitude_of_central_meridian||central_meridian||+lon_0||Longitude of false origin||8822||!FalseOriginLong|| ||
     117|| || ||latitude_of_projection_origin||latitude_of_origin||+lat_0||Latitude of false origin||8821||!FalseOriginLat|| ||
     118||||||false_easting||false_easting||+x_0||Easting at false origin||8826||!FalseEasting||||
     119||||||false_northing||false_northing||+y_0||Northing at false origin||8827||!FalseNorthing||||
     120|| || || || || || || || || ||
     121||'''CEA'''||Lambert cylindrical equal area||lambert_cylindrical_equal_area||Cylindrical_Equal_Area||+proj=cea||N/A||||CT_CylindricalEqualArea ||(3) CF says EPSG 9834/9835 ?||
     122|| || ||longitude_of_central_meridian||central_meridian||+lon_0|||| ||!NatOriginLong|| ||
     123|| || ||standard_parallel![1]||standard_parallel_1||+lat_ts||||||!StdParallel1||default to 0||
     124||||||false_easting||false_easting||+x_0||||||!FalseEasting||||
     125||||||false_northing||false_northing||+y_0||||||!FalseNorthing||||
     126|| || || || || || || || || ||
     127||'''M-1SP'''||Mercator (1SP)||mercator||Mercator_1SP||+proj=merc||Mercator (variant A)||9804||Mercator_1SP||(3)||
     128|| || ||longitude_of_projection_origin||central_meridian||+lon_0||Longitude of natural origin||8801||!NatOriginLong|| ||
     129|| || ||scale_factor_at_projection_origin||scale_factor||+k_0||Scale factor at natural origin||8805||!ScaleAtNatOrigin|| ||
     130||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     131||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     132|| || || || || || || || || ||
     133||'''M-2SP'''||Mercator (2SP)||mercator||Mercator_2SP||+proj=merc||Mercator (variant B)||9805||N/A||(3)||
     134|| || ||longitude_of_projection_origin||central_meridian||+lon_0||Longitude of natural origin||8801|||| ||
     135|| || ||standard_parallel![1]||standard_parallel_1||+lat_ts||Latitude of 1st standard parallel||8823|||| ||
     136||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     137||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     138|| || || || || || || || || ||
     139||'''Ortho'''||Orthographic||orthographic||Orthographic||+proj=ortho||Orthographic||9840||CT_Orthographic|| ||
     140|| || ||longitude_of_projection_origin||central_meridian||+lon_0||Longitude of natural origin||8802||!ProjCenterLong|| ||
     141|| || ||latitude_of_projection_origin||latitude_of_origin||+lat_0||Latitude of natural origin||8801||!ProjCenterLat|| ||
     142||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     143||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     144|| || || || || || || || || ||
     145||'''PS-A'''||Polar stereographic||polar_stereographic||Polar_Stereographic||+proj=stere||Polar Stereographic (variant A)||9810||CT_PolarStereographic ||(3) ||
     146|| || ||straight_vertical_longitude_from_pole  ||central_meridian||+lon_0||Longitude of natural origin||8802||!StraightVertPoleLong||||
     147||||||latitude_of_projection_origin||N/A||+lat_0||Latitude of natural origin||8801||!NatOriginLat||+90/-90||
     148|| || ||scale_factor_at_projection_origin||scale_factor||+k_0||Scale factor at natural origin||8805||!ScaleAtNatOrigin|| ||
     149||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     150||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     151|| || || || || || || || || ||
     152||'''PS-B'''||Polar stereographic||polar_stereographic||Polar_Stereographic||+proj=stere||Polar Stereographic (variant B)||9829||N/A||(3)||
     153|| || ||straight_vertical_longitude_from_pole  ||central_meridian||+lon_0||Longitude of natural origin||8802||||||
     154||||||latitude_of_projection_origin||N/A||+lat_0||Longitude of origin||8801||||+90/-90||
     155||||||standard_parallel||latitude_of_origin||+lat_ts||Latitude of standard parallel||8832||||||
     156||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     157||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     158|| || || || || || || || || ||
     159||'''St'''||Stereographic||stereographic||Stereographic||+proj=stere||N/A||||CT_Stereographic||EPSG 9809 is “Oblique Stereographic” or “Double Stereographic”||
     160|| || ||longitude_of_projection_origin||central_meridian||+lon_0|||| ||!ProjCenterLong|| ||
     161|| || ||latitude_of_projection_origin||latitude_of_origin||+lat_0|||| ||!ProjCenterLat|| ||
     162|| || ||scale_factor_at_projection_origin||scale_factor||+k_0|||| ||!ScaleAtNatOrigin|| ||
     163||||||false_easting||false_easting||+x_0||||||!FalseEasting||||
     164||||||false_northing||false_northing||+y_0||||||!FalseNorthing||||
     165|| || || || || || || || || ||
     166||'''TM'''||Transverse Mercator||transverse_mercator||Transverse_Mercator||+proj=tmerc||Transverse Mercator||9807||CT_TransverseMercator||(3)||
     167|| || ||scale_factor_at_central_meridian||scale_factor||+k_0||Scale factor at natural origin||8805||!ScaleAtNatOrigin|| ||
     168|| || ||longitude_of_central_meridian||central_meridian||+lon_0||Longitude of natural origin||8802||!NatOriginLong|| ||
     169|| || ||latitude_of_projection_origin||latitude_of_origin||+lat_0||Latitude of natural origin||8801||!NatOriginLat|| ||
     170||||||false_easting||false_easting||+x_0||False easting||8806||!FalseEasting||||
     171||||||false_northing||false_northing||+y_0||False northing||8807||!FalseNorthing||||
     172
     173=== '''Notes:''' ===
     174
     175 1. Multiple CF/WKT translations, see projection-specific translations.
     176 2. Parameter used in every projection.
     177 3. See projection-specific notes.
     178
     179=== Projection-specific notes ===
     180
     181EPSG codes below correspond to "EPSG dataset coordinate operation method" codes.
     182
     183==== Lambert conformal 1SP / 2SP ====
     184
     185The 1SP variant corresponds to EPSG code 9801 - Lambert Conic Conformal (1SP), with CF latitude_of_projection_origin=standard_parallel and WKT scale_factor=1. A scale factor less than 1 means that there are 2 standard parallels (see http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_1sp.html), but it cannot be translated to the CF 1SP variant, therefore the 2SP variant should be used instead. The 2SP variant corresponds to EPSG code 9802 - Lambert Conic Conformal (2SP).
     186
     187==== Lambert cylindrical equal area ====
     188
     189The scale_factor_at_projection_origin variant is not recommended as it does not translate to and from WKT/PROJ.4. Snyder formulas 10-2b and 10-2 can be used to relate scale_factor_at_projection_origin, standard_parallel1 and latitude_of_projection_origin but the latter is not part of this projection's parameters. It has been proposed to deprecate or remove this variant from the CF spec (see CF trac ticket #75).
     190
     191==== Mercator 1SP / 2SP ====
     192The scale_factor_at_projection_origin variant corresponds to EPSG code 9804 - Mercator (1SP) or Mercator (variant A), and the standard_parallel variant corresponds to EPSG code 9805 - Mercator (2SP) or Mercator (variant B).
     193
     194==== Polar stereographic ====
     195
     196The standard_parallel variant corresponds to EPSG code 9829 - Polar Stereographic (Variant B), while the scale_factor_at_projection_origin variant corresponds to EPSG code 9810 - Polar Stereographic (Variant A). As WKT/PROJ.4 require the standard parallel, [Snyder] formula 21-7 can be used to compute it from scale_factor_at_projection_origin if that variant is used.
     197
     198==== Transverse Mercator ====
     199
     200Transverse Mercator can be translated to PROJ.4 using either +proj=tmerc (Transverse Mercator) or +proj=utm (Universal Transverse Mercator) by computing zone number from longitude_of_central_meridian.
     201For example, a TM projection with longitude_of_central_meridian=-117 would have the corresponding PROJ.4 string: '+proj=utm +zone=11 +datum=NAD27 +units=m +no_defs '
     202
     203
     204
     205= Mapping from CF Grid Mapping Attributes to CRS WKT Elements (previous table by Phil Bentley, Oct 2011) =
    2206
    3207These ''provisional'' mappings have been compiled to support, among other things, CF proposal [ticket:69].
     
    33237|| `standard_parallel` (two parallels) || `PARAMETER["Latitude of 1st standard parallel", <value>], PARAMETER["Latitude of 2nd standard parallel", <value>]` ||
    34238|| `straight_vertical_longitude_from_pole` || `PARAMETER["Longitude of origin", <value>]` ||
    35 
    36 [[br]]
    37 -- Phil Bentley, Oct 2011