public static Plane constructNormalizedYPlane(final double x,final double z,final double DValue){
  if (Math.abs(x) < MINIMUM_RESOLUTION && Math.abs(z) < MINIMUM_RESOLUTION)   return null;
  final double denom=1.0 / Math.sqrt(x * x + z * z);
  return new Plane(z * denom,0.0,-x * denom,DValue);
}

public static Plane constructNormalizedYPlane ( final double x , final double z , final double DValue ) { if ( Math . abs ( x ) < MINIMUM_RESOLUTION && Math . abs ( z ) < MINIMUM_RESOLUTION ) return null ; final double denom = 1.0 / Math . sqrt ( x * x + z * z ) ; return new Plane ( z * denom , 0.0 , - x * denom , DValue ) ; }
construct a normalized plane through an x - z point and parallel to the y axis . if the x - z point is at ( 0 , 0 ) , return null .
