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delphine |
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<?php
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/**
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* Author : Julien Moquet
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*
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* Inspired by Proj4php from Mike Adair madairATdmsolutions.ca
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* and Richard Greenwood rich@greenwoodma$p->com
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* License: LGPL as per: http://www.gnu.org/copyleft/lesser.html
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*/
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/* * *****************************************************************************
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NAME MERCATOR
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PURPOSE: Transforms input longitude and latitude to Easting and
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Northing for the Mercator projection. The
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longitude and latitude must be in radians. The Easting
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and Northing values will be returned in meters.
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PROGRAMMER DATE
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---------- ----
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D. Steinwand, EROS Nov, 1991
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T. Mittan Mar, 1993
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ALGORITHM REFERENCES
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1. Snyder, John P., "Map Projections--A Working Manual", U.S. Geological
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Survey Professional Paper 1395 (Supersedes USGS Bulletin 1532), United
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State Government Printing Office, Washington D.C., 1987.
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2. Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
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U.S. Geological Survey Professional Paper 1453 , United State Government
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Printing Office, Washington D.C., 1989.
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* ***************************************************************************** */
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//static double r_major = a; /* major axis */
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//static double r_minor = b; /* minor axis */
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//static double lon_center = long0; /* Center longitude (projection center) */
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//static double lat_origin = lat0; /* center latitude */
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//static double e,es; /* eccentricity constants */
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//static double m1; /* small value m */
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//static double false_northing = y0; /* y offset in meters */
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//static double false_easting = x0; /* x offset in meters */
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//scale_fact = k0
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class Proj4phpProjMerc {
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public function init() {
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//?$this->temp = $this->r_minor / $this->r_major;
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//$this->temp = $this->b / $this->a;
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//$this->es = 1.0 - sqrt($this->temp);
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//$this->e = sqrt( $this->es );
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//?$this->m1 = cos($this->lat_origin) / (sqrt( 1.0 - $this->es * sin($this->lat_origin) * sin($this->lat_origin)));
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//$this->m1 = cos(0.0) / (sqrt( 1.0 - $this->es * sin(0.0) * sin(0.0)));
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if( $this->lat_ts ) {
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if( $this->sphere ) {
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$this->k0 = cos( $this->lat_ts );
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} else {
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$this->k0 = Proj4php::$common->msfnz( $this->es, sin( $this->lat_ts ), cos( $this->lat_ts ) );
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}
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}
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}
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/* Mercator forward equations--mapping lat,long to x,y
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-------------------------------------------------- */
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public function forward( $p ) {
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//alert("ll2m coords : ".coords);
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$lon = $p->x;
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$lat = $p->y;
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// convert to radians
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if( $lat * Proj4php::$common->R2D > 90.0 &&
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$lat * Proj4php::$common->R2D < -90.0 &&
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$lon * Proj4php::$common->R2D > 180.0 &&
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$lon * Proj4php::$common->R2D < -180.0 ) {
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Proj4php::reportError( "merc:forward: llInputOutOfRange: " . $lon . " : " . $lat );
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return null;
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}
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if( abs( abs( $lat ) - Proj4php::$common->HALF_PI ) <= Proj4php::$common->EPSLN ) {
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Proj4php::reportError( "merc:forward: ll2mAtPoles" );
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return null;
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} else {
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if( $this->sphere ) {
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$x = $this->x0 + $this->a * $this->k0 * Proj4php::$common->adjust_lon( $lon - $this->long0 );
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$y = $this->y0 + $this->a * $this->k0 * log( tan( Proj4php::$common->FORTPI + 0.5 * $lat ) );
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} else {
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$sinphi = sin( lat );
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$ts = Proj4php::$common . tsfnz( $this->e, $lat, $sinphi );
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$x = $this->x0 + $this->a * $this->k0 * Proj4php::$common->adjust_lon( $lon - $this->long0 );
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$y = $this->y0 - $this->a * $this->k0 * log( $ts );
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}
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$p->x = $x;
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$p->y = $y;
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return $p;
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}
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}
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/* Mercator inverse equations--mapping x,y to lat/long
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-------------------------------------------------- */
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public function inverse( $p ) {
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$x = $p->x - $this->x0;
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$y = $p->y - $this->y0;
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if( $this->sphere ) {
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$lat = Proj4php::$common->HALF_PI - 2.0 * atan( exp( -$y / $this->a * $this->k0 ) );
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} else {
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$ts = exp( -$y / ($this->a * $this->k0) );
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$lat = Proj4php::$common->phi2z( $this->e, $ts );
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if( $lat == -9999 ) {
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Proj4php::reportError( "merc:inverse: lat = -9999" );
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return null;
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}
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}
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$lon = Proj4php::$common->adjust_lon( $this->long0 + $x / ($this->a * $this->k0) );
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$p->x = $lon;
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$p->y = $lat;
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return $p;
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}
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}
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Proj4php::$proj['merc'] = new Proj4phpProjMerc();
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