public function testGetFirstEccentricitySquared()
{
$referenceEllipsoidObject = new ReferenceEllipsoid(ReferenceEllipsoid::MODIFIED_AIRY);
$firstEccentricitySquared = $referenceEllipsoidObject->getFirstEccentricitySquared();
$this->assertEquals(0.0066705399999854, $firstEccentricitySquared, '', 1.0E-7);
$referenceEllipsoidObject->setEllipsoid(ReferenceEllipsoid::WGS_1984);
$firstEccentricitySquared = $referenceEllipsoidObject->getFirstEccentricitySquared();
$this->assertEquals(0.0066943799901413, $firstEccentricitySquared, '', 1.0E-7);
}
/**
* Get the Area of this region
*
* The algorithm used here is derived from the algorithm used by the GRASS GIS package
*
* @param ReferenceEllipsoid|null $ellipsoid Reference Ellipsoid to use for this calculation
* If null, then the WGS 1984 Ellipsoid will be used
* @return Area The area of this region
*/
public function getArea(ReferenceEllipsoid $ellipsoid = null)
{
$pointCount = count($this->nodePoints);
if ($pointCount == 0) {
return new Area();
} elseif (is_null($ellipsoid)) {
$ellipsoid = new ReferenceEllipsoid(ReferenceEllipsoid::WGS_1984);
}
$semiMajorAxis = $ellipsoid->getSemiMajorAxis();
$eccentricitySquared = $ellipsoid->getFirstEccentricitySquared();
$eccentricity4 = $eccentricitySquared * $eccentricitySquared;
$eccentricity6 = $eccentricity4 * $eccentricitySquared;
$AE = $semiMajorAxis * $semiMajorAxis * (1 - $eccentricitySquared);
$this->QA = 2.0 / 3.0 * $eccentricitySquared;
$this->QB = 3.0 / 5.0 * $eccentricity4;
$this->QC = 4.0 / 7.0 * $eccentricity6;
$this->QbarA = -1.0 - 2.0 / 3.0 * $eccentricitySquared - 3.0 / 5.0 * $eccentricity4 - 4.0 / 7.0 * $eccentricity6;
$this->QbarB = 2.0 / 9.0 * $eccentricitySquared + 2.0 / 5.0 * $eccentricity4 + 4.0 / 7.0 * $eccentricity6;
$this->QbarC = -(3.0 / 25.0) * $eccentricity4 - 12.0 / 35.0 * $eccentricity6;
$this->QbarD = 4.0 / 49.0 * $eccentricity6;
$Qp = $this->_Q(M_PI_2);
$pointCount--;
$longitude2 = $this->nodePoints[$pointCount]->getLongitude()->getValue(Angle::RADIANS);
$latitude2 = $this->nodePoints[$pointCount]->getLatitude()->getValue(Angle::RADIANS);
$Qbar2 = $this->_Qbar($latitude2);
$area = 0.0;
$n = 0;
while ($n++ < $pointCount) {
$longitude1 = $longitude2;
$latitude1 = $latitude2;
$Qbar1 = $Qbar2;
$longitude2 = $this->nodePoints[$n]->getLongitude()->getValue(Angle::RADIANS);
$latitude2 = $this->nodePoints[$n]->getLatitude()->getValue(Angle::RADIANS);
$Qbar2 = $this->_Qbar($latitude2);
self::datelineAdjust($longitude1, $longitude2);
$deltaLongitude = $longitude2 - $longitude1;
$area += $deltaLongitude * ($Qp - $this->_Q($latitude2));
if (($deltaLatitude = $latitude2 - $latitude1) != 0.0) {
$area += $deltaLongitude * $this->_Q($latitude2) - $deltaLongitude / $deltaLatitude * ($Qbar2 - $Qbar1);
}
}
$area = self::polarAdjust($area, $AE, $Qp);
return new Area($area);
}
