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| -rw-r--r-- | docs/source/usage/index.rst | 1 | ||||
| -rw-r--r-- | docs/source/usage/resource_files.rst | 121 |
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diff --git a/docs/source/usage/index.rst b/docs/source/usage/index.rst index d59296d0..c581fd03 100644 --- a/docs/source/usage/index.rst +++ b/docs/source/usage/index.rst @@ -16,7 +16,6 @@ command line applications or the C API that is a part of the software package. apps/index projections transformation - resource_files environmentvars operations/index diff --git a/docs/source/usage/resource_files.rst b/docs/source/usage/resource_files.rst deleted file mode 100644 index 7a1dea8b..00000000 --- a/docs/source/usage/resource_files.rst +++ /dev/null @@ -1,121 +0,0 @@ -.. _resource_files: - -================================================================================ -Resource files -================================================================================ - -A number of files containing preconfigured transformations and default parameters -for certain projections are bundled with the PROJ distribution. Init files -contains preconfigured proj-strings for various coordinate reference systems -and the defaults file contains default values for parameters of select -projections. - -Init files -------------------------------------------------------------------------------- - -Init files are used for preconfiguring proj-strings for often used -transformations, such as those found in the EPSG database. Most init files contain -transformations from a given coordinate reference system to WGS84. This makes -it easy to transformations between any two coordinate reference systems with -``cs2cs``. Init files can however contain any proj-string and don't necesarily -have to follow the *cs2cs* paradigm where WGS84 is used as a pivot datum. The -ITRF init file is a good example of that. - -A number of init files come pre-bundled with PROJ but it is also possible to -add your own custom init files. PROJ looks for the init files in the directoty -listed in the ``PROJ_LIB`` environment variable. - -The format of init files made up of a identifier in angled brackets and a -proj-string: - -:: - - <3819> +proj=longlat +ellps=bessel - +towgs84=595.48,121.69,515.35,4.115,-2.9383,0.853,-3.408 +no_defs <> - -The above example is the first entry from the ``epsg`` init file. So, this is the -coordinate reference system with ID 3819 in the EPSG database. Comments can be -inserted by prefixing them with a "#". With version 4.10.0 a new special metadata -entry is now accepted in init files. It can be parsed with a function from the public -API. The metadata entry in the epsg init file looks like this at the time of writing: - -:: - -<metadata> +version=9.0.0 +origin=EPSG +lastupdate=2017-01-10 - -Pre-configured proj-strings from init files are used in the following way: - -:: - - $ cs2cs -v +proj=latlong +to +init=epsg:3819 - # ---- From Coordinate System ---- - #Lat/long (Geodetic alias) - # - # +proj=latlong +ellps=WGS84 - # ---- To Coordinate System ---- - #Lat/long (Geodetic alias) - # - # +init=epsg:3819 +proj=longlat +ellps=bessel - # +towgs84=595.48,121.69,515.35,4.115,-2.9383,0.853,-3.408 +no_defs - -It is possible to override parameters when using ``+init``. Just add the parameter -to the proj-string alongside the ``+init`` parameter. For instance by overriding -the ellipsoid as in the following example - -:: - - +init=epsg:25832 +ellps=intl - -where the Hayford ellipsoid is used instead of the predefined GRS80 ellipsoid. -It is also possible to add additional parameters not specified in the init file, -for instance by adding an obervation epoch when transforming from ITRF2000 to -ITRF2005: - -:: - - +init=ITRF2000:ITRF2005 +tobs=2010.5 - -which then expands to - -:: - - +proj=helmert +x=-0.0001 +y=0.0008 +z=0.0058 +s=-0.0004 - +dx=0.0002 +dy=-0.0001 +dz=0.0018 +ds=-0.000008 - +epoch=2000.0 +transpose - +tobs=2010.5 - -Below is a list of the init files that are packaged with PROJ. - - ======== ================================================================ - Name Description - ======== ================================================================ - esri Auto-generated mapping from Esri projection index. Not - maintained any more - epsg EPSG database - GL27 Great Lakes Grids - IGNF French coordinate systems supplied by the IGNF - ITRF2000 Full set of transformation parameters between ITRF2000 and other - ITRF's - ITRF2008 Full set of transformation parameters between ITRF2008 and other - ITRF's - ITRF2014 Full set of transformation parameters between ITRF2014 and other - ITRF's - nad27 State plane coordinate systems, North American Datum 1927 - nad83 State plane coordinate systems, North American Datum 1983 - ======== ================================================================ - - -Defaults file -------------------------------------------------------------------------------- - -The ``proj_def.dat`` file supplies default parameters for PROJ. It uses the same -syntax as the init files described above. The identifiers in the defaults file -describe to what the parameters should apply. If the ``<general>`` identifier is -used, then all parameters in that section applies for all proj-strings. Otherwise -the identifier is connected to a specific projection. With the defaults file -supplied with PROJ the default ellipsoid is set to WGS84 (for all proj-strings). -Apart from that only the Albers Equal Area, -:doc:`Lambert Conic Conformal<operations/projections/lcc>` and the -:doc:`Lagrange<operations/projections/lagrng>` projections have default parameters. -Defaults can be ignored by adding the ``+no_def`` parameter to a proj-string. - |