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diff --git a/proj.dox b/proj.dox new file mode 100644 index 00000000..ccb71b0d --- /dev/null +++ b/proj.dox @@ -0,0 +1,154 @@ +/*! \mainpage PROJ.4 Programmer's Manual + +<h2>PROJ.4 Programmer's Manual</h2> + +<a href="http://trac.osgeo.org/proj/">PROJ.4 - Cartographic Projections Library</a> + + +<h3>DESCRIPTION</h3> + +Procedure pj_init selects and initializes a cartographic projection with its +argument control parameters. Argc is the number of elements in the array of +control strings argv that each contain individual cartographic control keyword +assignments (+ proj arguments). The list must contain at least the +proj=projection and Earth's radius or elliptical parameters. If the +initialization of the projection is successful a valid address is returned +otherwise a NULL value. + +The pj_init_plus function operates similarly to pj_init but takes a single +string containing the definition, with each parameter prefixed with a plus sign. + For example "+proj=utm +zone=11 +ellps=WGS84". + +Once initialization is performed either forward or inverse projections can be +performed with the returned value of pj_init used as the argument proj. The +argument structure projUV values u and v contain respective longitude and +latitude or x and y. Latitude and longitude are in radians. If a projection +operation fails, both elements of projUV are set to HUGE_VAL (defined in +math.h). + +Note: all projections have a forward mode, but some do not have an inverse +projection. If the projection does not have an inverse the projPJ structure element +inv will be NULL. + +The pj_transform function may be used to transform points between the two +provided coordinate systems. In addition to converting between cartographic +projection coordinates and geographic coordinates, this function also takes care +of datum shifts if possible between the source and destination coordinate +system. Unlike pj_fwd and pj_inv it is also allowable for the coordinate system +definitions (projPJ *) to be geographic coordinate systems (defined as ++proj=latlong). The x, y and z arrays contain the input values of the points, +and are replaced with the output values. The function returns zero on success, +or the error number (also in pj_errno) on failure. + +Memory associated with the projection may be freed with pj_free. + + +<h3>EXAMPLE</h3> + +The following program reads latitude and longitude +values in decimal degress, performs Mercator +projection with a Clarke 1866 ellipsoid and +a 33° latitude of true scale and prints the projected +cartesian values in meters: + +\verbatim + #include <proj_api.h> + + main(int argc, char **argv) { + char *args[] = { "proj=merc", "ellps=clrk66", "lat_ts=33" }; + projUV p; + projPJ pj; + + if (!(pj = pj_init(3, args))) + exit(1); + while (scanf("%lf %lf", &p.v, &p.u) == 2) { + p.u *= DEG_TO_RAD; + p.v *= DEG_TO_RAD; + p = pj_fwd(p, pj); + printf("%.2f\t%.2f\n", p.u, p.v); + } + exit(0); + } +\endverbatim + +<h3>API Functions</h3> + +XY pj_fwd( LP lp, PJ *P ); + +LP pj_inv( XY xy, PJ *P ); + +int pj_transform( PJ *srcdefn, PJ *dstdefn, long point_count, int point_offset, double *x, double *y, double *z ); + +int pj_datum_transform( PJ *srcdefn, PJ *dstdefn, long point_count, int point_offset, double *x, double *y, double *z ); + +int pj_compare_datums( PJ *srcdefn, PJ *dstdefn ); + +int pj_geocentric_to_geodetic( double a, double es, long point_count, int point_offset, double *x, double *y, double *z ); + +int pj_geodetic_to_geocentric( double a, double es, long point_count, int point_offset, double *x, double *y, double *z ); + +int pj_apply_gridshift( const char *nadgrids, int inverse, long point_count, int point_offset, double *x, double *y, double *z ); + +void pj_deallocate_grids( void ); + +int pj_is_latlong( PJ *pj ); + +int pj_is_geocent( PJ *pj ); + +void pj_pr_list( PJ *P ); + +void pj_set_finder( const char *(*new_finder)(const char *) ); + +void pj_set_searchpath ( int count, const char **path ); + +projPJ pj_init(int, char **); + +projPJ pj_init_plus(const char *); + +char *pj_get_def( projPJ, int ); + +projPJ pj_latlong_from_proj( PJ *pj_in ); + +void *pj_malloc( size_t ); + +void pj_dalloc( void * ); + +void pj_free( PJ *P ); + +char *pj_strerrno( int ); + +int *pj_get_errno_ref( void ); + +const char *pj_get_release( void ); + + +<h3>SEE ALSO</h3> + +<h3>Documentation</h3> +<ul> +<li><a href="http://pubs.er.usgs.gov/usgspubs/pp/pp1395">Snyder, 1987: Map projections; a working manual</a>. +</li> +<li><a href="http://www.asprs.org/resources/GRIDS/">Grids & Datums</a>: Clifford J. Mugnier's columns in PE&RS. +</li> +<li><a href="http://www.mapref.org">MapRef</a>: Assorted general information on projections, and related topics. +</li> +<li><a href="http://earth-info.nga.mil/GandG/publications/index.htm">NGA Publications on Geodesy</a>. +</li> +<li><a href="http://www.progonos.com/furuti/MapProj/CartIndex/cartIndex.html">Map projections</a>: An introduction to cartography emphasizing map projections: their properties, applications and basic mathematics. +</li> +<li><a href="http://www.galleryofmapprojections.com/">Paul B. Anderson's Map Projections Site</a>. +</li> +</ul> + +<h3>Software</h3> +<ul> +<li><a href="http://ftp.dfg.ca.gov/Public/BDB/Tools/proj4/proj_api.zip">PROJ.4 VB Wrappers</a> from Eric G. Miller.</li> +<li><a href="http://www.proj4js.org/">PROJ4JS</a> - Javascript projections implementation.</li> +<li><a href="http://gmt.soest.hawaii.edu/">GMT</a> - Generic Mapping Tools, includes reprojection services.</li> +<li><a href="http://edc.usgs.gov/pub/software/gctpc/">GCTPC</a>: The other widely used projection package from the USGS.</li> +<li><a href="http://earth-info.nga.mil/GandG/geotrans/index.htm">Geotrans</a>: a projections and datum shift program from NIMA/NGA.</li> +<li><a href="http://www.jhlabs.com/java/maps/proj/">JHLabs Java Map Projection Library</a>: Loosely derived from PROJ.4 with similar syntax.</li> +<li><a href="http://geotools.org/">GeoTools</a>: GeoTools is a Java GIS library that includes sophisticated projections support.</li> +</ul> + +*/ |