/**
* Create a Geodetic point from a Geocentric point.
*/
public static function fromGeocentric(Geocentric $point)
{
// Local definitions and variables
// end-criterium of loop, accuracy of sin(Latitude)
$genau = 1.0E-12;
$genau2 = $genau * $genau;
$maxiter = 30;
$X = $point->x;
$Y = $point->y;
// Z value not always supplied
// CHECKME: this does not make sense. Without Z we are talking about a flat
// plain, and not a 3D point in space.
$Z = $point->z ? $point->z : 0.0;
/*
$P; // distance between semi-minor axis and location
$RR; // distance between center and location
$CT; // sin of geocentric latitude
$ST; // cos of geocentric latitude
$RX;
$RK;
$RN; // Earth radius at location
$CPHI0; // cos of start or old geodetic latitude in iterations
$SPHI0; // sin of start or old geodetic latitude in iterations
$CPHI; // cos of searched geodetic latitude
$SPHI; // sin of searched geodetic latitude
$SDPHI; // end-criterium: addition-theorem of sin(Latitude(iter)-Latitude(iter-1))
$at_pole; // indicates location is in polar region
$iter; // of continous iteration, max. 30 is always enough (s.a.)
$lon;
$lat;
$height;
*/
$a = $point->getEllipsoid()->a;
$b = $point->getEllipsoid()->b;
$at_pole = false;
// The distance from the axis passing through the poles.
$P = sqrt($X * $X + $Y * $Y);
$RR = sqrt($X * $X + $Y * $Y + $Z * $Z);
// Special cases for latitude and longitude.
if ($P / $a < $genau) {
// Special case: at the poles if P=0. (X=0, Y=0)
$at_pole = true;
$lon = 0.0;
// If (X,Y,Z)=(0,0,0) then Height becomes semi-minor axis
// of ellipsoid (=center of mass) and Latitude becomes PI/2
if ($RR / $a < $genau) {
$lat = M_PI_2;
$height = -$b;
return;
}
} else {
// Ellipsoidal (geodetic) longitude interval:
// -PI < Longitude <= +PI
$lon = atan2($Y, $X);
}
// The eccentricity squared.
$es = $point->getEllipsoid()->es;
/* --------------------------------------------------------------
* Following iterative algorithm was developped by
* "Institut für Erdmessung", University of Hannover, July 1988.
* Internet: www.ife.uni-hannover.de
* Iterative computation of CPHI,SPHI and Height.
* Iteration of CPHI and SPHI to 10**-12 radian res$p->
* 2*10**-7 arcsec.
* --------------------------------------------------------------
*/
$CT = $Z / $RR;
$ST = $P / $RR;
$RX = 1.0 / sqrt(1.0 - $es * (2.0 - $es) * $ST * $ST);
$CPHI0 = $ST * (1.0 - $es) * $RX;
$SPHI0 = $CT * $RX;
$iter = 0;
// Loop to find sin(Latitude) res $p-> Latitude
// until |sin(Latitude(iter)-Latitude(iter-1))| < genau
do {
++$iter;
$RN = $a / sqrt(1.0 - $es * $SPHI0 * $SPHI0);
// Ellipsoidal (geodetic) height
$height = $P * $CPHI0 + $Z * $SPHI0 - $RN * (1.0 - $es * $SPHI0 * $SPHI0);
$RK = $es * $RN / ($RN + $height);
$RX = 1.0 / sqrt(1.0 - $RK * (2.0 - $RK) * $ST * $ST);
$CPHI = $ST * (1.0 - $RK) * $RX;
$SPHI = $CT * $RX;
$SDPHI = $SPHI * $CPHI0 - $CPHI * $SPHI0;
$CPHI0 = $CPHI;
$SPHI0 = $SPHI;
} while ($SDPHI * $SDPHI > $genau2 && $iter < $maxiter);
// Ellipsoidal (geodetic) latitude
$lat = atan($SPHI / abs($CPHI));
// Create a new Geodetic coordinate.
// Keep the same datum as the current point.
$geodetic_point = new static(rad2deg($lat), rad2deg($lon), $height, $point->getDatum());
return $geodetic_point;
}
/**
* Convert a geocentric point from the WGS84 datum.
*/
public function fromWgs84(Geocentric $point)
{
if ($this->type == static::TYPE_3TERM) {
$x = $point->x - $this->params[0];
$y = $point->y - $this->params[1];
$z = $point->z - $this->params[2];
} elseif ($this->type == static::TYPE_7TERM) {
$Dx_BF = $this->params[0];
$Dy_BF = $this->params[1];
$Dz_BF = $this->params[2];
// These need converting from seconds of arc to radians.
$Rx_BF = $this->params[3] * static::SEC_TO_RAD;
$Ry_BF = $this->params[4] * static::SEC_TO_RAD;
$Rz_BF = $this->params[5] * static::SEC_TO_RAD;
// Convert parts per million to a multiplier
$M_BF = 1 + $this->params[6] * static::PPM_TO_MULT;
$x_tmp = ($point->x - $Dx_BF) / $M_BF;
$y_tmp = ($point->y - $Dy_BF) / $M_BF;
$z_tmp = ($point->z - $Dz_BF) / $M_BF;
$x = $x_tmp + $Rz_BF * $y_tmp - $Ry_BF * $z_tmp;
$y = -$Rz_BF * $x_tmp + $y_tmp + $Rx_BF * $z_tmp;
$z = $Ry_BF * $x_tmp - $Rx_BF * $y_tmp + $z_tmp;
} else {
throw new Excreption('Unknown datum transformation parameter type');
}
// Give the point the new datum.
$new_point = $point->withOrdinates($x, $y, $z)->withDatum($this);
return $new_point;
}
