/**
* Convert geodetic lat/lng to Earth Centered Rotational xyz
*
* @param Circle $circle
* @return Vector
*/
private function getECRVector(Circle $circle)
{
$x = $this->earthRadius * (cos(deg2rad($circle->getLat())) * cos(deg2rad($circle->getLng())));
$y = $this->earthRadius * (cos(deg2rad($circle->getLat())) * sin(deg2rad($circle->getLng())));
$z = $this->earthRadius * sin(deg2rad($circle->getLat()));
return new Vector(array($x, $y, $z));
}
