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/tags/v5.6-arganeraie/scripts/modules/ifn/bibliotheque/proj4php/projCode/vandg.php
New file
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<?php
/**
* Author : Julien Moquet
*
* Inspired by Proj4php from Mike Adair madairATdmsolutions.ca
* and Richard Greenwood rich@greenwoodma$p->com
* License: LGPL as per: http://www.gnu.org/copyleft/lesser.html
*/
/*******************************************************************************
NAME VAN DER GRINTEN
 
PURPOSE: Transforms input Easting and Northing to longitude and
latitude for the Van der Grinten projection. The
Easting and Northing must be in meters. The longitude
and latitude values will be returned in radians.
 
PROGRAMMER DATE
---------- ----
T. Mittan March, 1993
 
This function was adapted from the Van Der Grinten projection code
(FORTRAN) in the General Cartographic Transformation Package software
which is available from the U.S. Geological Survey National Mapping Division.
 
ALGORITHM REFERENCES
 
1. "New Equal-Area Map Projections for Noncircular Regions", John P. Snyder,
The American Cartographer, Vol 15, No. 4, October 1988, pp. 341-355.
 
2. Snyder, John P., "Map Projections--A Working Manual", U.S. Geological
Survey Professional Paper 1395 (Supersedes USGS Bulletin 1532), United
State Government Printing Office, Washington D.C., 1987.
 
3. "Software Documentation for GCTP General Cartographic Transformation
Package", U.S. Geological Survey National Mapping Division, May 1982.
* ***************************************************************************** */
 
class Proj4phpProjVandg {
/* Initialize the Van Der Grinten projection
---------------------------------------- */
public function init() {
$this->R = 6370997.0; //Radius of earth
}
 
/**
*
* @param type $p
* @return type
*/
public function forward( $p ) {
 
$lon = $p->x;
$lat = $p->y;
 
/* Forward equations
----------------- */
$dlon = Proj4php::$common->adjust_lon( $lon - $this->long0 );
$x;
$y;
 
if( abs( $lat ) <= Proj4php::$common->EPSLN ) {
$x = $this->x0 + $this->R * $dlon;
$y = $this->y0;
}
$theta = Proj4php::$common . asinz( 2.0 * abs( $lat / Proj4php::$common->PI ) );
if( (abs( $dlon ) <= Proj4php::$common->EPSLN) || (abs( abs( $lat ) - Proj4php::$common->HALF_PI ) <= Proj4php::$common->EPSLN) ) {
$x = $this->x0;
if( $lat >= 0 ) {
$y = $this->y0 + Proj4php::$common->PI * $this->R * tan( .5 * $theta );
} else {
$y = $this->y0 + Proj4php::$common->PI * $this->R * - tan( .5 * $theta );
}
// return(OK);
}
$al = .5 * abs( (Proj4php::$common->PI / $dlon) - ($dlon / Proj4php::$common->PI) );
$asq = $al * $al;
$sinth = sin( $theta );
$costh = cos( $theta );
 
$g = $costh / ($sinth + $costh - 1.0);
$gsq = $g * $g;
$m = $g * (2.0 / $sinth - 1.0);
$msq = $m * $m;
$con = Proj4php::$common->PI * $this->R * ($al * ($g - $msq) + sqrt( $asq * ($g - $sq) * ($g - $msq) - ($msq + $asq) * ($gsq - $msq) )) / ($msq + $asq);
if( $dlon < 0 ) {
$con = -$con;
}
$x = $this->x0 + $con;
$con = abs( $con / (Proj4php::$common->PI * $this->R) );
if( $lat >= 0 ) {
$y = $this->y0 + Proj4php::$common->PI * $this->R * sqrt( 1.0 - $con * $con - 2.0 * $al * $con );
} else {
$y = $this->y0 - Proj4php::$common->PI * $this->R * sqrt( 1.0 - $con * $con - 2.0 * $al * $con );
}
$p->x = $x;
$p->y = $y;
return $p;
}
 
/* Van Der Grinten inverse equations--mapping x,y to lat/long
--------------------------------------------------------- */
 
public function inverse( $p ) {
/*
$dlon;
$xx;
$yy;
$xys;
$c1;
$c2;
$c3;
$al;
$asq;
$a1;
$m1;
$con;
$th1;
$d;
*/
/* inverse equations
----------------- */
$p->x -= $this->x0;
$p->y -= $this->y0;
$con = Proj4php::$common->PI * $this->R;
$xx = $p->x / $con;
$yy = $p->y / $con;
$xys = $xx * $xx + $yy * $yy;
$c1 = -abs( $yy ) * (1.0 + $xys);
$c2 = $c1 - 2.0 * $yy * $yy + $xx * $xx;
$c3 = -2.0 * $c1 + 1.0 + 2.0 * $yy * $yy + $xys * $xys;
$d = $yy * $yy / $c3 + (2.0 * $c2 * $c2 * $c2 / $c3 / $c3 / $c3 - 9.0 * $c1 * $c2 / $c3 / $c3) / 27.0;
$a1 = ($c1 - $c2 * $c2 / 3.0 / $c3) / $c3;
$m1 = 2.0 * sqrt( -$a1 / 3.0 );
$con = ((3.0 * $d) / $a1) / $m1;
if( abs( $con ) > 1.0 ) {
if( $con >= 0.0 ) {
$con = 1.0;
} else {
$con = -1.0;
}
}
$th1 = acos( $con ) / 3.0;
if( $p->$y >= 0 ) {
$lat = (-$m1 * cos( $th1 + Proj4php::$common->PI / 3.0 ) - $c2 / 3.0 / $c3) * Proj4php::$common->PI;
} else {
$lat = -(-m1 * cos( $th1 + Proj4php::$common->PI / 3.0 ) - $c2 / 3.0 / $c3) * Proj4php::$common->PI;
}
 
if( abs( $xx ) < Proj4php::$common->EPSLN ) {
$lon = $this->$long0;
}
$lon = Proj4php::$common->adjust_lon( $this->long0 + Proj4php::$common->PI * ($xys - 1.0 + sqrt( 1.0 + 2.0 * ($xx * $xx - $yy * $yy) + $xys * $xys )) / 2.0 / $xx );
 
$p->x = $lon;
$p->y = $lat;
return $p;
}
 
}
 
Proj4php::$proj['vandg'] = new Proj4phpProjVandg();