| 1 |
<appendix label="F" id="appendix-grid-mappings"> |
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| 2 |
<title>Grid Mappings</title> |
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| 3 |
<para> |
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Each recognized grid mapping is described in one of the sections |
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| 5 |
below. Each section contains: the valid name that is used with the |
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<varname>grid_mapping_name</varname> |
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| 7 |
attribute; a list of the specific attributes |
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| 8 |
that may be used to assign values to the mapping's parameters; |
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| 9 |
the standard names used to identify the coordinate variables that |
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| 10 |
contain the mapping's independent variables; and references to the |
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mapping's definition or other information that may help in using the |
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mapping. Since the attributes used to set a mapping's parameters may |
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| 13 |
be shared among several mappings, their definitions are contained |
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| 14 |
in a table in the final section. |
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| 15 |
<emphasis role="newtext">The attributes which describe the |
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ellipsoid and prime meridian may be included, when applicable, with |
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any grid mapping.</emphasis> |
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| 18 |
</para> |
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<para> |
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We have used the FGDC "Content Standard for Digital Geospatial |
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| 21 |
Metadata" |
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| 22 |
<biblioref linkend="fgdc"/> |
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| 23 |
as a guide in choosing the values for |
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| 24 |
<varname>grid_mapping_name</varname> |
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| 25 |
and the attribute names for the parameters |
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| 26 |
describing map projections. |
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| 27 |
</para> |
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|
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| 29 |
<simplesect> |
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| 30 |
<title>Albers Equal Area</title> |
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| 31 |
<programlisting> |
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| 32 |
<varname>grid_mapping_name</varname> = albers_conical_equal_area |
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| 33 |
</programlisting> |
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| 34 |
<variablelist> |
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| 35 |
<varlistentry> |
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| 36 |
<term><emphasis>Map parameters:</emphasis></term> |
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| 37 |
<listitem> |
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| 38 |
<para> |
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| 39 |
<itemizedlist> |
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| 40 |
<listitem> |
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| 41 |
<para> |
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| 42 |
<varname>standard_parallel</varname> - There may be 1 or 2 values. |
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| 43 |
</para> |
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| 44 |
</listitem> |
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| 45 |
<listitem> |
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<para><varname>longitude_of_central_meridian</varname></para> |
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| 47 |
</listitem> |
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| 48 |
<listitem> |
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| 49 |
<para><varname>latitude_of_projection_origin</varname></para> |
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| 50 |
</listitem> |
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| 51 |
<listitem> |
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<para><varname>false_easting</varname></para> |
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| 53 |
</listitem> |
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| 54 |
<listitem> |
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| 55 |
<para><varname>false_northing</varname></para> |
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| 56 |
</listitem> |
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| 57 |
</itemizedlist> |
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| 58 |
</para> |
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| 59 |
</listitem> |
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| 60 |
</varlistentry> |
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| 61 |
|
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| 62 |
<varlistentry> |
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| 63 |
<term><emphasis>Map coordinates:</emphasis></term> |
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| 64 |
<listitem> |
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| 65 |
<para> |
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| 66 |
The x (abscissa) and y (ordinate) rectangular coordinates |
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| 67 |
are identified by the <varname>standard_name</varname> |
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attribute values <varname>projection_x_coordinate</varname> and |
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<varname>projection_y_coordinate</varname> respectively. |
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| 70 |
</para> |
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| 71 |
</listitem> |
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| 72 |
</varlistentry> |
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| 73 |
|
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| 74 |
<varlistentry> |
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| 75 |
<term><emphasis>Notes:</emphasis></term> |
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| 76 |
<listitem> |
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| 77 |
<para> |
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| 78 |
Notes on using the <varname>PROJ.4</varname> software package for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/albers_equal_area_conic.html">http://www.remotesensing.org/geotiff/proj_list/albers_equal_area_conic.html</ulink>. |
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| 79 |
</para> |
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| 80 |
</listitem> |
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| 81 |
</varlistentry> |
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| 82 |
</variablelist> |
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| 83 |
</simplesect> |
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| 84 |
|
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| 85 |
<simplesect id="azimuthal-equidistant"> |
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| 86 |
<title>Azimuthal equidistant</title> |
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| 87 |
<para> |
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| 88 |
<programlisting> |
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| 89 |
<varname>grid_mapping_name</varname> = azimuthal_equidistant |
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| 90 |
</programlisting> |
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| 91 |
|
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| 92 |
<variablelist> |
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| 93 |
<varlistentry> |
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| 94 |
<term><emphasis>Map parameters:</emphasis></term> |
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| 95 |
<listitem> |
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| 96 |
<para> |
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| 97 |
<itemizedlist> |
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| 98 |
<listitem> |
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| 99 |
<para><varname>longitude_of_projection_origin</varname></para> |
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</listitem> |
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| 101 |
<listitem> |
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| 102 |
<para><varname>latitude_of_projection_origin</varname></para> |
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| 103 |
</listitem> |
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| 104 |
<listitem> |
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| 105 |
<para><varname>false_easting</varname></para> |
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| 106 |
</listitem> |
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| 107 |
<listitem> |
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<para><varname>false_northing</varname></para> |
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| 109 |
</listitem> |
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| 110 |
</itemizedlist> |
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| 111 |
</para> |
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| 112 |
</listitem> |
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| 113 |
</varlistentry> |
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| 114 |
|
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| 115 |
<varlistentry> |
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<term><emphasis>Map coordinates:</emphasis></term> |
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| 117 |
<listitem> |
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| 118 |
<para> |
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| 119 |
The x (abscissa) and y (ordinate) rectangular coordinates |
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| 120 |
are identified by the <varname>standard_name</varname> attribute values |
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| 121 |
<varname>projection_x_coordinate</varname> |
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| 122 |
and <varname>projection_y_coordinate</varname> respectively. |
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| 123 |
</para> |
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| 124 |
</listitem> |
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| 125 |
</varlistentry> |
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| 126 |
|
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| 127 |
<varlistentry> |
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| 128 |
<term><emphasis>Notes:</emphasis></term> |
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| 129 |
<listitem> |
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| 130 |
<para> |
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| 131 |
Notes on using the <varname>PROJ.4</varname> software package for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/azimuthal_equidistant.html">http://www.remotesensing.org/geotiff/proj_list/azimuthal_equidistant.html</ulink>. |
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| 132 |
</para> |
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| 133 |
</listitem> |
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| 134 |
</varlistentry> |
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| 135 |
</variablelist> |
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| 136 |
</para> |
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| 137 |
</simplesect> |
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| 138 |
|
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| 139 |
<simplesect id="lambert-azimuthal-equal-area"> |
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| 140 |
<title>Lambert azimuthal equal area</title> |
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| 141 |
<para> |
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| 142 |
<programlisting> |
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| 143 |
<varname>grid_mapping_name</varname> = lambert_azimuthal_equal_area |
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| 144 |
</programlisting> |
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| 145 |
|
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| 146 |
<variablelist> |
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| 147 |
<varlistentry> |
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| 148 |
<term><emphasis>Map parameters:</emphasis></term> |
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| 149 |
<listitem> |
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| 150 |
<para> |
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| 151 |
<itemizedlist> |
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| 152 |
<listitem> |
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| 153 |
<para><varname>longitude_of_projection_origin</varname></para> |
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| 154 |
</listitem> |
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| 155 |
<listitem> |
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| 156 |
<para><varname>latitude_of_projection_origin</varname></para> |
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| 157 |
</listitem> |
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| 158 |
<listitem> |
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| 159 |
<para><varname>false_easting</varname></para> |
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| 160 |
</listitem> |
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| 161 |
<listitem> |
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| 162 |
<para><varname>false_northing</varname></para> |
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| 163 |
</listitem> |
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| 164 |
</itemizedlist> |
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| 165 |
</para> |
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| 166 |
</listitem> |
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| 167 |
</varlistentry> |
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| 168 |
|
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| 169 |
<varlistentry> |
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| 170 |
<term><emphasis>Map coordinates:</emphasis></term> |
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| 171 |
<listitem> |
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| 172 |
<para> |
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| 173 |
The x (abscissa) and y (ordinate) rectangular coordinates |
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| 174 |
are identified by the <varname>standard_name</varname> attribute values |
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| 175 |
<varname>projection_x_coordinate</varname> |
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| 176 |
and <varname>projection_y_coordinate</varname> respectively. |
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| 177 |
</para> |
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| 178 |
</listitem> |
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| 179 |
</varlistentry> |
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| 180 |
|
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| 181 |
<varlistentry> |
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| 182 |
<term><emphasis>Notes:</emphasis></term> |
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| 183 |
<listitem> |
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| 184 |
<para> |
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| 185 |
Notes on using the <varname>PROJ.4</varname> software package for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/lambert_azimuthal_equal_area.html">http://www.remotesensing.org/geotiff/proj_list/lambert_azimuthal_equal_area.html</ulink>. |
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| 186 |
</para> |
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| 187 |
</listitem> |
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| 188 |
</varlistentry> |
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| 189 |
</variablelist> |
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| 190 |
</para> |
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| 191 |
</simplesect> |
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| 192 |
|
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| 193 |
<simplesect> |
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| 194 |
<title>Lambert conformal</title> |
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| 195 |
<para> |
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| 196 |
<programlisting> |
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| 197 |
<varname>grid_mapping_name</varname> = lambert_conformal_conic |
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| 198 |
</programlisting> |
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| 199 |
|
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| 200 |
<variablelist> |
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| 201 |
<varlistentry> |
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| 202 |
<term><emphasis>Map parameters:</emphasis></term> |
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| 203 |
<listitem> |
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| 204 |
<para> |
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| 205 |
<itemizedlist> |
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| 206 |
<listitem> |
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| 207 |
<para><varname>standard_parallel</varname> - There may be 1 or 2 values.</para> |
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| 208 |
</listitem> |
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| 209 |
<listitem> |
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| 210 |
<para><varname>longitude_of_central_meridian</varname></para> |
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| 211 |
</listitem> |
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| 212 |
<listitem> |
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| 213 |
<para><varname>latitude_of_projection_origin</varname></para> |
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| 214 |
</listitem> |
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| 215 |
<listitem> |
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| 216 |
<para><varname>false_easting</varname></para> |
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| 217 |
</listitem> |
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| 218 |
<listitem> |
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| 219 |
<para><varname>false_northing</varname></para> |
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| 220 |
</listitem> |
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| 221 |
</itemizedlist> |
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</para> |
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| 223 |
</listitem> |
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| 224 |
</varlistentry> |
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| 225 |
|
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| 226 |
<varlistentry> |
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| 227 |
<term><emphasis>Map coordinates:</emphasis></term> |
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| 228 |
<listitem> |
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| 229 |
<para> |
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| 230 |
The x (abscissa) and y (ordinate) rectangular coordinates |
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| 231 |
are identified by the <varname>standard_name</varname> attribute values |
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| 232 |
<varname>projection_x_coordinate</varname> |
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| 233 |
and <varname>projection_y_coordinate</varname> respectively. |
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| 234 |
</para> |
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| 235 |
</listitem> |
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| 236 |
</varlistentry> |
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| 237 |
|
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| 238 |
<varlistentry> |
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| 239 |
<term><emphasis>Notes:</emphasis></term> |
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| 240 |
<listitem> |
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| 241 |
<para> |
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| 242 |
Notes on using the <varname>PROJ.4</varname> software package for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_2sp.html">http://www.remotesensing.org/geotiff/proj_list/lambert_conic_conformal_2sp.html</ulink>. |
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| 243 |
</para> |
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| 244 |
</listitem> |
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| 245 |
</varlistentry> |
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| 246 |
</variablelist> |
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| 247 |
</para> |
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| 248 |
</simplesect> |
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| 249 |
|
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| 250 |
|
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| 251 |
<simplesect> |
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| 252 |
<title> |
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| 253 |
<emphasis role="newtext">Lambert Cylindrical Equal Area</emphasis> |
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| 254 |
</title> |
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| 255 |
<programlisting> |
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| 256 |
<emphasis role="newtext"><varname>grid_mapping_name</varname> = lambert_cylindrical_equal_area</emphasis> |
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| 257 |
</programlisting> |
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| 258 |
<variablelist> |
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| 259 |
<varlistentry> |
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| 260 |
<term><emphasis><emphasis role="newtext">Map parameters:</emphasis></emphasis></term> |
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| 261 |
<listitem><para><emphasis role="newtext"> |
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| 262 |
<itemizedlist> |
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| 263 |
<listitem> |
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| 264 |
<emphasis role="newtext"><varname>longitude_of_central_meridian</varname></emphasis> |
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| 265 |
</listitem> |
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| 266 |
<listitem> |
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| 267 |
<emphasis role="newtext">Either <varname>standard_parallel</varname> or <varname>scale_factor_at_projection_origin</varname></emphasis> |
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| 268 |
</listitem> |
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| 269 |
<listitem> |
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| 270 |
<emphasis role="newtext"><varname>false_easting</varname></emphasis> |
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| 271 |
</listitem> |
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| 272 |
<listitem> |
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| 273 |
<emphasis role="newtext"><varname>false_northing</varname></emphasis> |
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| 274 |
</listitem> |
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| 275 |
</itemizedlist> |
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| 276 |
</emphasis></para></listitem> |
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| 277 |
</varlistentry> |
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| 278 |
<varlistentry> |
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| 279 |
<term><emphasis><emphasis role="newtext">Map coordinates:</emphasis></emphasis></term> |
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| 280 |
<listitem><para><emphasis role="newtext"> |
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| 281 |
<emphasis role="newtext">The x (abscissa) and y (ordinate) rectangular coordinates are identified by the <varname>standard_name</varname> attribute value <varname>projection_x_coordinate</varname> and <varname>projection_y_coordinate</varname> respectively.</emphasis> |
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| 282 |
</emphasis></para></listitem> |
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| 283 |
</varlistentry> |
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| 284 |
<varlistentry> |
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| 285 |
<term><emphasis><emphasis role="newtext">Notes:</emphasis></emphasis></term> |
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| 286 |
<listitem><para><emphasis role="newtext"> |
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| 287 |
Notes on using the PROJ.4 software packages for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/cylindrical_equal_area.html">http://www.remotesensing.org/geotiff/proj_list/cylindrical_equal_area.html</ulink> ("Lambert Cylindrical Equal Area" or EPSG 9834 or EPSG 9835). Detailed formulas can be found in [Snyder] pages 76-85. |
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| 288 |
</emphasis></para></listitem> |
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| 289 |
</varlistentry> |
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| 290 |
</variablelist> |
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| 291 |
</simplesect> |
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| 292 |
|
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| 293 |
|
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| 294 |
<simplesect> |
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| 295 |
<title><emphasis role="newtext">Latitude-Longitude</emphasis></title> |
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| 296 |
<programlisting> |
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| 297 |
<emphasis role="newtext"><varname>grid_mapping_name</varname> = latitude_longitude</emphasis> |
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| 298 |
</programlisting> |
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| 299 |
<para><emphasis role="newtext"> |
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| 300 |
This grid mapping defines the canonical 2D geographical |
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| 301 |
coordinate system based upon latitude and longitude |
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| 302 |
coordinates on a spherical Earth. It is included so |
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| 303 |
that the figure of the Earth can be described. |
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| 304 |
</emphasis></para> |
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| 305 |
<variablelist> |
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| 306 |
<varlistentry> |
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| 307 |
<term><emphasis><emphasis role="newtext">Map parameters:</emphasis></emphasis></term> |
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| 308 |
<listitem><para><emphasis role="newtext"> |
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| 309 |
None. |
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| 310 |
</emphasis></para></listitem> |
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| 311 |
</varlistentry> |
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| 312 |
<varlistentry> |
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| 313 |
<term><emphasis><emphasis role="newtext">Map coordinates:</emphasis></emphasis></term> |
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| 314 |
<listitem><para><emphasis role="newtext"> |
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| 315 |
The rectangular coordinates are longitude and latitude |
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| 316 |
identified by the usual conventions |
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| 317 |
(<xref linkend="latitude-coordinate"/> and <xref linkend="longitude-coordinate"/>). |
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| 318 |
</emphasis></para></listitem> |
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| 319 |
</varlistentry> |
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| 320 |
</variablelist> |
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| 321 |
</simplesect> |
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| 322 |
|
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| 323 |
|
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| 324 |
<simplesect> |
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| 325 |
<title> |
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| 326 |
<emphasis role="newtext">Mercator</emphasis> |
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| 327 |
</title> |
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| 328 |
<programlisting> |
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| 329 |
<emphasis role="newtext"><varname>grid_mapping_name</varname> = mercator</emphasis> |
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| 330 |
</programlisting> |
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| 331 |
<variablelist> |
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| 332 |
<varlistentry> |
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| 333 |
<term><emphasis><emphasis role="newtext">Map parameters:</emphasis></emphasis></term> |
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| 334 |
<listitem><para><emphasis role="newtext"> |
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| 335 |
<itemizedlist> |
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| 336 |
<listitem> |
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| 337 |
<emphasis role="newtext"><varname>longitude_of_projection_origin</varname></emphasis> |
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| 338 |
</listitem> |
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| 339 |
<listitem> |
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| 340 |
<emphasis role="newtext">Either <varname>standard_parallel</varname> (EPSG 9805) or <varname>scale_factor_at_projection_origin</varname> (EPSG 9804)</emphasis> |
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| 341 |
</listitem> |
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| 342 |
<listitem> |
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| 343 |
<emphasis role="newtext"><varname>false_easting</varname></emphasis> |
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| 344 |
</listitem> |
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| 345 |
<listitem> |
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| 346 |
<emphasis role="newtext"><varname>false_northing</varname></emphasis> |
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| 347 |
</listitem> |
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| 348 |
</itemizedlist> |
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| 349 |
</emphasis></para></listitem> |
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| 350 |
</varlistentry> |
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| 351 |
<varlistentry> |
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| 352 |
<term><emphasis><emphasis role="newtext">Map coordinates:</emphasis></emphasis></term> |
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| 353 |
<listitem><para><emphasis role="newtext"> |
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| 354 |
The x (abscissa) and y (ordinate) rectangular coordinates are identified by the <varname>standard_name</varname> attribute value <varname>projection_x_coordinate</varname> and <varname>projection_y_coordinate</varname> respectively. |
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| 355 |
</emphasis></para></listitem> |
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| 356 |
</varlistentry> |
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| 357 |
<varlistentry> |
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| 358 |
<term><emphasis><emphasis role="newtext">Notes:</emphasis></emphasis></term> |
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| 359 |
<listitem><para><emphasis role="newtext"> |
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| 360 |
Notes on using the PROJ.4 software packages for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/mercator_1sp.html">http://www.remotesensing.org/geotiff/proj_list/mercator_1sp.html</ulink> ("Mercator (1SP)" or EPSG 9804) or <ulink url="http://www.remotesensing.org/geotiff/proj_list/mercator_2sp.html">http://www.remotesensing.org/geotiff/proj_list/mercator_2sp.html</ulink> ("Mercator (2SP)" or EPSG 9805). |
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| 361 |
</emphasis></para> |
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| 362 |
<para><emphasis role="newtext"> |
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| 363 |
More information on formulas available in <biblioref linkend="ogp-epsg_gn7_2">[OGP/EPSG_GN7_2]</biblioref>. |
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| 364 |
</emphasis></para></listitem> |
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| 365 |
</varlistentry> |
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| 366 |
</variablelist> |
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| 367 |
</simplesect> |
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| 368 |
|
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| 369 |
|
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| 370 |
<simplesect> |
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| 371 |
<title><emphasis role="newtext">Orthographic</emphasis></title> |
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| 372 |
<programlisting> |
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| 373 |
<emphasis role="newtext"><varname>grid_mapping_name</varname> = orthographic</emphasis> |
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| 374 |
</programlisting> |
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| 375 |
<variablelist> |
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| 376 |
<varlistentry> |
|---|
| 377 |
<term><emphasis><emphasis role="newtext">Map parameters:</emphasis></emphasis></term> |
|---|
| 378 |
<listitem><para><emphasis role="newtext"> |
|---|
| 379 |
<itemizedlist> |
|---|
| 380 |
<listitem> |
|---|
| 381 |
<emphasis role="newtext"><varname>longitude_of_projection_origin</varname></emphasis> |
|---|
| 382 |
</listitem> |
|---|
| 383 |
<listitem> |
|---|
| 384 |
<emphasis role="newtext"><varname>latitude_of_projection_origin</varname></emphasis> |
|---|
| 385 |
</listitem> |
|---|
| 386 |
<listitem> |
|---|
| 387 |
<emphasis role="newtext"><varname>false_easting</varname></emphasis> |
|---|
| 388 |
</listitem> |
|---|
| 389 |
<listitem> |
|---|
| 390 |
<emphasis role="newtext"><varname>false_northing</varname></emphasis> |
|---|
| 391 |
</listitem> |
|---|
| 392 |
</itemizedlist> |
|---|
| 393 |
</emphasis></para></listitem> |
|---|
| 394 |
</varlistentry> |
|---|
| 395 |
<varlistentry> |
|---|
| 396 |
<term><emphasis><emphasis role="newtext">Map coordinates:</emphasis></emphasis></term> |
|---|
| 397 |
<listitem><para><emphasis role="newtext"> |
|---|
| 398 |
The x (abscissa) and y (ordinate) rectangular coordinates are identified by the <varname>standard_name</varname> attribute value <varname>projection_x_coordinate</varname> and <varname>projection_y_coordinate</varname> respectively. |
|---|
| 399 |
</emphasis></para></listitem> |
|---|
| 400 |
</varlistentry> |
|---|
| 401 |
<varlistentry> |
|---|
| 402 |
<term><emphasis><emphasis role="newtext">Notes:</emphasis></emphasis></term> |
|---|
| 403 |
<listitem><para><emphasis role="newtext"> |
|---|
| 404 |
Notes on using the PROJ.4 software packages for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/orthographic.html">http://www.remotesensing.org/geotiff/proj_list/orthographic.html</ulink> ("Orthographic" or EPSG 9840). |
|---|
| 405 |
</emphasis></para> |
|---|
| 406 |
<para><emphasis role="newtext"> |
|---|
| 407 |
More information on formulas available in <biblioref linkend="ogp-epsg_gn7_2">[OGP/EPSG_GN7_2]</biblioref>. |
|---|
| 408 |
</emphasis></para></listitem> |
|---|
| 409 |
</varlistentry> |
|---|
| 410 |
</variablelist> |
|---|
| 411 |
</simplesect> |
|---|
| 412 |
|
|---|
| 413 |
|
|---|
| 414 |
<simplesect id="polar-stereographic"> |
|---|
| 415 |
<title>Polar stereographic</title> |
|---|
| 416 |
<programlisting> |
|---|
| 417 |
<varname>grid_mapping_name</varname> = polar_stereographic |
|---|
| 418 |
</programlisting> |
|---|
| 419 |
<variablelist> |
|---|
| 420 |
<varlistentry> |
|---|
| 421 |
<term><emphasis>Map parameters:</emphasis></term> |
|---|
| 422 |
<listitem> |
|---|
| 423 |
<para> |
|---|
| 424 |
<itemizedlist> |
|---|
| 425 |
<listitem> |
|---|
| 426 |
<para><varname>straight_vertical_longitude_from_pole</varname></para> |
|---|
| 427 |
</listitem> |
|---|
| 428 |
<listitem> |
|---|
| 429 |
<para><varname>latitude_of_projection_origin</varname> - Either +90. or -90.</para> |
|---|
| 430 |
</listitem> |
|---|
| 431 |
<listitem> |
|---|
| 432 |
<para>Either <varname>standard_parallel</varname> or <varname>scale_factor_at_projection_origin</varname></para> |
|---|
| 433 |
</listitem> |
|---|
| 434 |
<listitem> |
|---|
| 435 |
<para><varname>false_easting</varname></para> |
|---|
| 436 |
</listitem> |
|---|
| 437 |
<listitem> |
|---|
| 438 |
<para><varname>false_northing</varname></para> |
|---|
| 439 |
</listitem> |
|---|
| 440 |
</itemizedlist> |
|---|
| 441 |
</para> |
|---|
| 442 |
</listitem> |
|---|
| 443 |
</varlistentry> |
|---|
| 444 |
<varlistentry> |
|---|
| 445 |
<term><emphasis>Map coordinates:</emphasis></term> |
|---|
| 446 |
<listitem> |
|---|
| 447 |
<para> |
|---|
| 448 |
The x (abscissa) and y (ordinate) rectangular coordinates |
|---|
| 449 |
are identified by the <varname>standard_name</varname> attribute values |
|---|
| 450 |
<varname>projection_x_coordinate</varname> |
|---|
| 451 |
and <varname>projection_y_coordinate</varname> respectively. |
|---|
| 452 |
</para> |
|---|
| 453 |
</listitem> |
|---|
| 454 |
</varlistentry> |
|---|
| 455 |
|
|---|
| 456 |
<varlistentry> |
|---|
| 457 |
<term><emphasis>Notes:</emphasis></term> |
|---|
| 458 |
<listitem> |
|---|
| 459 |
<para> |
|---|
| 460 |
Notes on using the <varname>PROJ.4</varname> software package for computing the mapping may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html">http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html</ulink>. |
|---|
| 461 |
</para> |
|---|
| 462 |
</listitem> |
|---|
| 463 |
</varlistentry> |
|---|
| 464 |
</variablelist> |
|---|
| 465 |
</simplesect> |
|---|
| 466 |
|
|---|
| 467 |
<simplesect> |
|---|
| 468 |
<title>Rotated pole</title> |
|---|
| 469 |
<para> |
|---|
| 470 |
<programlisting> |
|---|
| 471 |
<varname>grid_mapping_name</varname> = rotated_latitude_longitude |
|---|
| 472 |
</programlisting> |
|---|
| 473 |
<variablelist> |
|---|
| 474 |
<varlistentry> |
|---|
| 475 |
<term><emphasis>Map parameters:</emphasis></term> |
|---|
| 476 |
<listitem> |
|---|
| 477 |
<para> |
|---|
| 478 |
<itemizedlist> |
|---|
| 479 |
<listitem> |
|---|
| 480 |
<para><varname>grid_north_pole_latitude</varname></para> |
|---|
| 481 |
</listitem> |
|---|
| 482 |
<listitem> |
|---|
| 483 |
<para><varname>grid_north_pole_longitude</varname></para> |
|---|
| 484 |
</listitem> |
|---|
| 485 |
<listitem> |
|---|
| 486 |
<para><varname>north_pole_grid_longitude</varname> - This parameter is option (default is 0).</para> |
|---|
| 487 |
</listitem> |
|---|
| 488 |
</itemizedlist> |
|---|
| 489 |
</para> |
|---|
| 490 |
</listitem> |
|---|
| 491 |
</varlistentry> |
|---|
| 492 |
|
|---|
| 493 |
<varlistentry> |
|---|
| 494 |
<term><emphasis>Map coordinates:</emphasis></term> |
|---|
| 495 |
<listitem> |
|---|
| 496 |
<para> |
|---|
| 497 |
The rotated latitude and longitude coordinates |
|---|
| 498 |
are identified by the <varname>standard_name</varname> attribute values |
|---|
| 499 |
<varname>grid_latitude</varname> |
|---|
| 500 |
and <varname>grid_longitude</varname> respectively. |
|---|
| 501 |
</para> |
|---|
| 502 |
</listitem> |
|---|
| 503 |
</varlistentry> |
|---|
| 504 |
|
|---|
| 505 |
<varlistentry> |
|---|
| 506 |
<term><emphasis>Notes:</emphasis></term> |
|---|
| 507 |
<listitem> |
|---|
| 508 |
<para></para> |
|---|
| 509 |
</listitem> |
|---|
| 510 |
</varlistentry> |
|---|
| 511 |
</variablelist> |
|---|
| 512 |
</para> |
|---|
| 513 |
</simplesect> |
|---|
| 514 |
|
|---|
| 515 |
|
|---|
| 516 |
<simplesect> |
|---|
| 517 |
<title>Stereographic</title> |
|---|
| 518 |
<para> |
|---|
| 519 |
<programlisting> |
|---|
| 520 |
<varname>grid_mapping_name</varname> = stereographic |
|---|
| 521 |
</programlisting> |
|---|
| 522 |
|
|---|
| 523 |
<variablelist> |
|---|
| 524 |
<varlistentry> |
|---|
| 525 |
<term><emphasis>Map parameters:</emphasis></term> |
|---|
| 526 |
<listitem> |
|---|
| 527 |
<para> |
|---|
| 528 |
<itemizedlist> |
|---|
| 529 |
<listitem> |
|---|
| 530 |
<para><varname>longitude_of_projection_origin</varname></para> |
|---|
| 531 |
</listitem> |
|---|
| 532 |
<listitem> |
|---|
| 533 |
<para><varname>latitude_of_projection_origin</varname></para> |
|---|
| 534 |
</listitem> |
|---|
| 535 |
<listitem> |
|---|
| 536 |
<para><varname>scale_factor_at_projection_origin</varname></para> |
|---|
| 537 |
</listitem> |
|---|
| 538 |
<listitem> |
|---|
| 539 |
<para><varname>false_easting</varname></para> |
|---|
| 540 |
</listitem> |
|---|
| 541 |
<listitem> |
|---|
| 542 |
<para><varname>false_northing</varname></para> |
|---|
| 543 |
</listitem> |
|---|
| 544 |
</itemizedlist> |
|---|
| 545 |
</para> |
|---|
| 546 |
</listitem> |
|---|
| 547 |
</varlistentry> |
|---|
| 548 |
|
|---|
| 549 |
<varlistentry> |
|---|
| 550 |
<term><emphasis>Map coordinates:</emphasis></term> |
|---|
| 551 |
<listitem> |
|---|
| 552 |
<para> |
|---|
| 553 |
The x (abscissa) and y (ordinate) rectangular coordinates |
|---|
| 554 |
are identified by the <varname>standard_name</varname> |
|---|
| 555 |
attribute values <varname>projection_x_coordinate</varname> |
|---|
| 556 |
and <varname>projection_y_coordinate</varname> respectively. |
|---|
| 557 |
</para> |
|---|
| 558 |
</listitem> |
|---|
| 559 |
</varlistentry> |
|---|
| 560 |
|
|---|
| 561 |
<varlistentry> |
|---|
| 562 |
<term><emphasis>Notes:</emphasis></term> |
|---|
| 563 |
<listitem> |
|---|
| 564 |
<para> |
|---|
| 565 |
Formulas for the mapping and its inverse along with notes on using the <varname>PROJ.4</varname> software package for doing the calcuations may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/stereographic.html">http://www.remotesensing.org/geotiff/proj_list/stereographic.html</ulink>. See the section "Polar stereographic" for the special case when the projection origin is one of the poles. |
|---|
| 566 |
</para> |
|---|
| 567 |
</listitem> |
|---|
| 568 |
</varlistentry> |
|---|
| 569 |
</variablelist> |
|---|
| 570 |
</para> |
|---|
| 571 |
</simplesect> |
|---|
| 572 |
|
|---|
| 573 |
|
|---|
| 574 |
<simplesect> |
|---|
| 575 |
<title>Transverse Mercator</title> |
|---|
| 576 |
<para> |
|---|
| 577 |
<programlisting> |
|---|
| 578 |
<varname>grid_mapping_name</varname> = transverse_mercator |
|---|
| 579 |
</programlisting> |
|---|
| 580 |
|
|---|
| 581 |
<variablelist> |
|---|
| 582 |
<varlistentry> |
|---|
| 583 |
<term><emphasis>Map parameters:</emphasis></term> |
|---|
| 584 |
<listitem> |
|---|
| 585 |
<para> |
|---|
| 586 |
<itemizedlist> |
|---|
| 587 |
<listitem> |
|---|
| 588 |
<para><varname>scale_factor_at_central_meridian</varname></para> |
|---|
| 589 |
</listitem> |
|---|
| 590 |
<listitem> |
|---|
| 591 |
<para><varname>longitude_of_central_meridian</varname></para> |
|---|
| 592 |
</listitem> |
|---|
| 593 |
<listitem> |
|---|
| 594 |
<para><varname>latitude_of_projection_origin</varname></para> |
|---|
| 595 |
</listitem> |
|---|
| 596 |
<listitem> |
|---|
| 597 |
<para><varname>false_easting</varname></para> |
|---|
| 598 |
</listitem> |
|---|
| 599 |
<listitem> |
|---|
| 600 |
<para><varname>false_northing</varname></para> |
|---|
| 601 |
</listitem> |
|---|
| 602 |
</itemizedlist> |
|---|
| 603 |
</para> |
|---|
| 604 |
</listitem> |
|---|
| 605 |
</varlistentry> |
|---|
| 606 |
|
|---|
| 607 |
<varlistentry> |
|---|
| 608 |
<term><emphasis>Map coordinates:</emphasis></term> |
|---|
| 609 |
<listitem> |
|---|
| 610 |
<para> |
|---|
| 611 |
The x (abscissa) and y (ordinate) rectangular coordinates |
|---|
| 612 |
are identified by the <varname>standard_name</varname> |
|---|
| 613 |
attribute values <varname>projection_x_coordinate</varname> |
|---|
| 614 |
and <varname>projection_y_coordinate</varname> respectively. |
|---|
| 615 |
</para> |
|---|
| 616 |
</listitem> |
|---|
| 617 |
</varlistentry> |
|---|
| 618 |
|
|---|
| 619 |
<varlistentry> |
|---|
| 620 |
<term><emphasis>Notes:</emphasis></term> |
|---|
| 621 |
<listitem> |
|---|
| 622 |
<para> |
|---|
| 623 |
Formulas for the mapping and its inverse along with notes on using the <varname>PROJ.4</varname> software package for doing the calcuations may be found at <ulink url="http://www.remotesensing.org/geotiff/proj_list/transverse_mercator.html">http://www.remotesensing.org/geotiff/proj_list/transverse_mercator.html</ulink>. |
|---|
| 624 |
</para> |
|---|
| 625 |
</listitem> |
|---|
| 626 |
</varlistentry> |
|---|
| 627 |
</variablelist> |
|---|
| 628 |
</para> |
|---|
| 629 |
</simplesect> |
|---|
| 630 |
|
|---|
| 631 |
<simplesect> |
|---|
| 632 |
<title><emphasis role="newtext">Vertical perspective</emphasis></title> |
|---|
| 633 |
<programlisting> |
|---|
| 634 |
<emphasis role="newtext"><varname>grid_mapping_name</varname> = vertical_perspective</emphasis> |
|---|
| 635 |
</programlisting> |
|---|
| 636 |
<variablelist> |
|---|
| 637 |
<varlistentry> |
|---|
| 638 |
<term><emphasis><emphasis role="newtext">Map parameters:</emphasis></emphasis></term> |
|---|
| 639 |
<listitem><para><itemizedlist> |
|---|
| 640 |
<listitem><para><varname><emphasis role="newtext">latitude_of_projection_origin</emphasis></varname></para></listitem> |
|---|
| 641 |
<listitem><para><varname><emphasis role="newtext">longitude_of_projection_origin</emphasis></varname></para></listitem> |
|---|
| 642 |
<listitem><para><varname><emphasis role="newtext">perspective_point_height</emphasis></varname></para></listitem> |
|---|
| 643 |
<listitem><para><varname><emphasis role="newtext">false_easting</emphasis></varname></para></listitem> |
|---|
| 644 |
<listitem><para><varname><emphasis role="newtext">false_northing</emphasis></varname></para></listitem> |
|---|
| 645 |
</itemizedlist></para></listitem> |
|---|
| 646 |
</varlistentry> |
|---|
| 647 |
<varlistentry> |
|---|
| 648 |
<term><emphasis><emphasis role="newtext">Map coordinates:</emphasis></emphasis></term> |
|---|
| 649 |
<listitem><para><emphasis role="newtext"> |
|---|
| 650 |
The x (abscissa) and y (ordinate) rectangular coordinates |
|---|
| 651 |
are identified by the <varname>standard_name</varname> attribute |
|---|
| 652 |
value <varname>projection_x_coordinate</varname> and |
|---|
| 653 |
<varname>projection_y_coordinate</varname> respectively. |
|---|
| 654 |
</emphasis></para></listitem> |
|---|
| 655 |
</varlistentry> |
|---|
| 656 |
<varlistentry> |
|---|
| 657 |
<term><emphasis><emphasis role="newtext">Notes:</emphasis></emphasis></term> |
|---|
| 658 |
<listitem><para><emphasis role="newtext"> |
|---|
| 659 |
Notes on using the <varname>PROJ.4</varname> software packages |
|---|
| 660 |
for computing the mapping may be found at |
|---|
| 661 |
<ulink url="http://www.remotesensing.org/geotiff/proj_list/geos.html">http://www.remotesensing.org/geotiff/proj_list/geos.html</ulink> |
|---|
| 662 |
. These notes assume the point of perspective |
|---|
| 663 |
is directly over the equator. A more general description |
|---|
| 664 |
of vertical perspective projection is given in |
|---|
| 665 |
<biblioref linkend="snyder">[Snyder]</biblioref>, pages 169-181. |
|---|
| 666 |
</emphasis></para></listitem> |
|---|
| 667 |
</varlistentry> |
|---|
| 668 |
</variablelist> |
|---|
| 669 |
</simplesect> |
|---|
| 670 |
|
|---|
| 671 |
<para> |
|---|
| 672 |
<emphasis role="newtext">In the following table the "Type" values are |
|---|
| 673 |
<emphasis role="bold">S</emphasis> for string and |
|---|
| 674 |
<emphasis role="bold">N</emphasis> for numeric.</emphasis> |
|---|
| 675 |
</para> |
|---|
| 676 |
|
|---|
| 677 |
<table frame="all"> |
|---|
| 678 |
<title>Grid Mapping Attributes</title> |
|---|
| 679 |
<tgroup cols="3" align="left" colsep="1" rowsep="1"> |
|---|
| 680 |
<colspec colwidth="4*"/> |
|---|
| 681 |
<colspec colwidth="0.5*"/> |
|---|
| 682 |
<colspec colwidth="4*"/> |
|---|
| 683 |
|
|---|
| 684 |
<thead> |
|---|
| 685 |
<row> |
|---|
| 686 |
<entry align="center">Attribute</entry> |
|---|
| 687 |
<entry align="center"><emphasis role="newtext">Type</emphasis></entry> |
|---|
| 688 |
<entry align="center">Description</entry> |
|---|
| 689 |
</row> |
|---|
| 690 |
</thead> |
|---|
| 691 |
<tbody> |
|---|
| 692 |
<row> |
|---|
| 693 |
<entry><emphasis role="newtext"><varname>earth_radius</varname></emphasis></entry> |
|---|
| 694 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 695 |
<entry><emphasis role="newtext"> |
|---|
| 696 |
Used to specify the radius, in metres, of the spherical |
|---|
| 697 |
figure used to approximate the shape of the Earth. This |
|---|
| 698 |
attribute should be specified for those projected coordinate |
|---|
| 699 |
reference systems in which the X-Y cartesian coordinates |
|---|
| 700 |
have been derived using a spherical Earth approximation. If |
|---|
| 701 |
the cartesian coordinates were derived using an ellipsoid, |
|---|
| 702 |
this attribute should not be defined. Example: "6371007", |
|---|
| 703 |
which is the radius of the GRS 1980 Authalic Sphere. |
|---|
| 704 |
</emphasis></entry> |
|---|
| 705 |
</row> |
|---|
| 706 |
|
|---|
| 707 |
<row> |
|---|
| 708 |
<entry><varname>false_easting</varname></entry> |
|---|
| 709 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 710 |
<entry> |
|---|
| 711 |
The value added to all abscissa values in the rectangular |
|---|
| 712 |
coordinates for a map projection. This value frequently |
|---|
| 713 |
is assigned to eliminate negative numbers. Expressed in |
|---|
| 714 |
the unit of the coordinate variable identified by the |
|---|
| 715 |
standard name <varname>projection_x_coordinate</varname>. |
|---|
| 716 |
</entry> |
|---|
| 717 |
</row> |
|---|
| 718 |
|
|---|
| 719 |
<row> |
|---|
| 720 |
<entry><varname>false_northing</varname></entry> |
|---|
| 721 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 722 |
<entry> |
|---|
| 723 |
The value added to all ordinate values in the rectangular |
|---|
| 724 |
coordinates for a map projection. This value frequently |
|---|
| 725 |
is assigned to eliminate negative numbers. Expressed in |
|---|
| 726 |
the unit of the coordinate variable identified by the |
|---|
| 727 |
standard name <varname>projection_y_coordinate</varname>. |
|---|
| 728 |
</entry> |
|---|
| 729 |
</row> |
|---|
| 730 |
<row> |
|---|
| 731 |
<entry><varname>grid_mapping_name</varname></entry> |
|---|
| 732 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 733 |
<entry> |
|---|
| 734 |
The name used to identify the grid mapping. |
|---|
| 735 |
</entry> |
|---|
| 736 |
</row> |
|---|
| 737 |
<row> |
|---|
| 738 |
<entry><varname>grid_north_pole_latitude</varname></entry> |
|---|
| 739 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 740 |
<entry> |
|---|
| 741 |
True latitude (degrees_north) of the north pole of the rotated grid. |
|---|
| 742 |
</entry> |
|---|
| 743 |
</row> |
|---|
| 744 |
<row> |
|---|
| 745 |
<entry><varname>grid_north_pole_longitude</varname></entry> |
|---|
| 746 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 747 |
<entry> |
|---|
| 748 |
True longitude (degrees_east) of the north pole of the rotated grid. |
|---|
| 749 |
</entry> |
|---|
| 750 |
</row> |
|---|
| 751 |
|
|---|
| 752 |
<row> |
|---|
| 753 |
<entry><emphasis role="newtext"><varname>inverse_flattening</varname></emphasis></entry> |
|---|
| 754 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 755 |
<entry><emphasis role="newtext"> |
|---|
| 756 |
Used to specify the <emphasis>inverse</emphasis> flattening |
|---|
| 757 |
(<emphasis>1/f</emphasis>) of the ellipsoidal figure |
|---|
| 758 |
associated with the geodetic datum and used to approximate the shape |
|---|
| 759 |
of the Earth. The flattening (<emphasis>f</emphasis>) of the ellipsoid |
|---|
| 760 |
is related to the semi-major and semi-minor axes by the formula |
|---|
| 761 |
<emphasis>f = (a-b)/a</emphasis>. In the case |
|---|
| 762 |
of a spherical Earth this attribute should be omitted or set to zero. |
|---|
| 763 |
Example: 298.257222101 for the GRS 1980 ellipsoid. (Note: By |
|---|
| 764 |
convention the dimensions of an ellipsoid are specified using either |
|---|
| 765 |
the semi-major and semi-minor axis lengths, or the semi-major axis |
|---|
| 766 |
length and the inverse flattening. If all three attributes are |
|---|
| 767 |
specified then the supplied values must be consistent with the |
|---|
| 768 |
aforementioned formula.) |
|---|
| 769 |
</emphasis></entry> |
|---|
| 770 |
</row> |
|---|
| 771 |
|
|---|
| 772 |
<row> |
|---|
| 773 |
<entry><varname>latitude_of_projection_origin</varname></entry> |
|---|
| 774 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 775 |
<entry> |
|---|
| 776 |
The latitude chosen as the origin of rectangular coordinates for a map projection. |
|---|
| 777 |
Domain: <varname>-90.0 <= latitude_of_projection_origin <= 90.0</varname> |
|---|
| 778 |
</entry> |
|---|
| 779 |
</row> |
|---|
| 780 |
<row> |
|---|
| 781 |
<entry><varname>longitude_of_central_meridian</varname></entry> |
|---|
| 782 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 783 |
<entry> |
|---|
| 784 |
The line of longitude at the center of a map projection generally used as the basis for constructing the projection. |
|---|
| 785 |
Domain: <varname>-180.0 <= longitude_of_central_meridian < 180.0</varname> |
|---|
| 786 |
</entry> |
|---|
| 787 |
</row> |
|---|
| 788 |
|
|---|
| 789 |
<row> |
|---|
| 790 |
<entry><emphasis role="newtext"><varname>longitude_of_prime_meridian</varname></emphasis></entry> |
|---|
| 791 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 792 |
<entry><emphasis role="newtext"> |
|---|
| 793 |
Specifies the longitude, with respect to Greenwich, of the prime |
|---|
| 794 |
meridian associated with the geodetic datum. The prime meridian defines |
|---|
| 795 |
the origin from which longitude values are determined. Not to be |
|---|
| 796 |
confused with the projection origin longitude |
|---|
| 797 |
(cf. <varname>longitude_of_projection_origin</varname>, a.k.a. central |
|---|
| 798 |
meridian) which defines the longitude of the map projection origin. |
|---|
| 799 |
Domain: <varname>-180.0 <= longitude_of_prime_meridian < 180.0</varname> decimal degrees. |
|---|
| 800 |
Default = <varname>0.0</varname> |
|---|
| 801 |
</emphasis></entry> |
|---|
| 802 |
</row> |
|---|
| 803 |
|
|---|
| 804 |
<row> |
|---|
| 805 |
<entry><varname>longitude_of_projection_origin</varname></entry> |
|---|
| 806 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 807 |
<entry> |
|---|
| 808 |
The longitude chosen as the origin of rectangular coordinates for a map projection. |
|---|
| 809 |
Domain: <varname>-180.0 <= longitude_of_projection_origin < 180.0</varname> |
|---|
| 810 |
</entry> |
|---|
| 811 |
</row> |
|---|
| 812 |
<row> |
|---|
| 813 |
<entry><varname>north_pole_grid_longitude</varname></entry> |
|---|
| 814 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 815 |
<entry> |
|---|
| 816 |
Longitude (degrees) of the true north pole in the rotated grid. |
|---|
| 817 |
</entry> |
|---|
| 818 |
</row> |
|---|
| 819 |
|
|---|
| 820 |
<row> |
|---|
| 821 |
<entry><emphasis role="newtext"><varname>perspective_point_height</varname></emphasis></entry> |
|---|
| 822 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 823 |
<entry><emphasis role="newtext"> |
|---|
| 824 |
Records the height, <emphasis>in metres</emphasis>, of the map |
|---|
| 825 |
projection perspective point above the ellipsoid (or sphere). Used |
|---|
| 826 |
by perspective-type map projections, for example the Vertical |
|---|
| 827 |
Perspective Projection, which may be used to simulate the view from |
|---|
| 828 |
a Meteosat satellite. |
|---|
| 829 |
</emphasis></entry> |
|---|
| 830 |
</row> |
|---|
| 831 |
|
|---|
| 832 |
<row> |
|---|
| 833 |
<entry><varname>scale_factor_at_central_meridian</varname></entry> |
|---|
| 834 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 835 |
<entry> |
|---|
| 836 |
A multiplier for reducing a distance obtained from a map by |
|---|
| 837 |
computation or scaling to the actual distance along the |
|---|
| 838 |
central meridian. |
|---|
| 839 |
Domain: <varname>scale_factor_at_central_meridian > 0.0</varname> |
|---|
| 840 |
</entry> |
|---|
| 841 |
</row> |
|---|
| 842 |
<row> |
|---|
| 843 |
<entry><varname>scale_factor_at_projection_origin</varname></entry> |
|---|
| 844 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 845 |
<entry> |
|---|
| 846 |
A multiplier for reducing a distance obtained from |
|---|
| 847 |
a map by computation or scaling to the actual distance |
|---|
| 848 |
at the projection origin. |
|---|
| 849 |
Domain: <varname>scale_factor_at_projection_origin > 0.0</varname> |
|---|
| 850 |
</entry> |
|---|
| 851 |
</row> |
|---|
| 852 |
|
|---|
| 853 |
<row> |
|---|
| 854 |
<entry><emphasis role="newtext"><varname>semi_major_axis</varname></emphasis></entry> |
|---|
| 855 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 856 |
<entry><emphasis role="newtext"> |
|---|
| 857 |
Specifies the length, <emphasis>in metres</emphasis>, of the semi-major |
|---|
| 858 |
axis of the ellipsoidal figure associated with the geodetic datum and |
|---|
| 859 |
used to approximate the shape of the Earth. Commonly denoted using the |
|---|
| 860 |
symbol <emphasis>a</emphasis>. In the case of a spherical Earth |
|---|
| 861 |
approximation this attribute defines the radius of the Earth. See |
|---|
| 862 |
also the <varname>inverse_flattening</varname> attribute. |
|---|
| 863 |
</emphasis></entry> |
|---|
| 864 |
</row> |
|---|
| 865 |
|
|---|
| 866 |
<row> |
|---|
| 867 |
<entry><emphasis role="newtext"><varname>semi_minor_axis</varname></emphasis></entry> |
|---|
| 868 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 869 |
<entry><emphasis role="newtext"> |
|---|
| 870 |
Specifies the length, <emphasis>in metres</emphasis>, of the semi-minor |
|---|
| 871 |
axis of the ellipsoidal figure associated with the geodetic datum and |
|---|
| 872 |
used to approximate the shape of the Earth. Commonly denoted using the |
|---|
| 873 |
symbol <emphasis>b</emphasis>. In the case of a spherical Earth |
|---|
| 874 |
approximation this attribute should be omitted (the preferred option) |
|---|
| 875 |
or else set equal to the value of the semi_major_axis attribute. See also the inverse_flattening attribute. |
|---|
| 876 |
</emphasis></entry> |
|---|
| 877 |
</row> |
|---|
| 878 |
|
|---|
| 879 |
<row> |
|---|
| 880 |
<entry><varname>standard_parallel</varname></entry> |
|---|
| 881 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 882 |
<entry><emphasis role="newtext"> |
|---|
| 883 |
Specifies the line, or lines, of latitude at which the developable map |
|---|
| 884 |
projection surface (plane, cone, or cylinder) touches the reference |
|---|
| 885 |
sphere or ellipsoid used to represent the Earth. Since there is zero |
|---|
| 886 |
scale distortion along a standard parallel it is also referred to as |
|---|
| 887 |
a "latitude of true scale". In the situation where a conical |
|---|
| 888 |
developable surface intersects the reference ellipsoid there are two |
|---|
| 889 |
standard parallels, in which case this attribute can be used as a |
|---|
| 890 |
vector to record both latitude values, with the additional convention |
|---|
| 891 |
that the standard parallel nearest the pole (N or S) is provided first. |
|---|
| 892 |
</emphasis> |
|---|
| 893 |
<emphasis role="deletedtext"> |
|---|
| 894 |
Line of constant latitude at which the surface of the |
|---|
| 895 |
Earth and plane or developable surface intersect. |
|---|
| 896 |
This attribute may be vector valued if two standard |
|---|
| 897 |
parallels are specified. |
|---|
| 898 |
</emphasis> |
|---|
| 899 |
Domain: <varname>-90.0 <= standard_parallel <= 90.0</varname> |
|---|
| 900 |
</entry> |
|---|
| 901 |
</row> |
|---|
| 902 |
<row> |
|---|
| 903 |
<entry><varname>straight_vertical_longitude_from_pole</varname></entry> |
|---|
| 904 |
<entry><emphasis role="newtext">N</emphasis></entry> |
|---|
| 905 |
<entry> |
|---|
| 906 |
The longitude to be oriented straight up from the North or South Pole. |
|---|
| 907 |
Domain: <varname>-180.0 <= straight_vertical_longitude_from_pole < 180.0</varname> |
|---|
| 908 |
</entry> |
|---|
| 909 |
</row> |
|---|
| 910 |
</tbody> |
|---|
| 911 |
</tgroup> |
|---|
| 912 |
</table> |
|---|
| 913 |
|
|---|
| 914 |
</appendix> |
|---|
