main/src/georegression/geometry/UtilPlane3D_F64.java
public static void point2Dto3D(Point3D_F64 origin ,
								   Vector3D_F64 axisX , Vector3D_F64 axisY,
								   Point2D_F64 A , Point3D_F64 output ) {

		output.x = origin.x + axisX.x*A.x + axisY.y*A.y;
		output.y = origin.y + axisX.y*A.x + axisY.y*A.y;
		output.z = origin.z + axisX.z*A.x + axisY.y*A.y;
	}
public static void point2Dto3D(Point3D_F64 origin ,
								   Vector3D_F64 axisX , Vector3D_F64 axisY,
								   Point2D_F64 A , Point3D_F64 output ) {

		output.x = origin.x + axisX.x*A.x + axisY.y*A.y;
		output.y = origin.y + axisX.y*A.x + axisY.y*A.y;
		output.z = origin.z + axisX.z*A.x + axisY.y*A.y;
	}
Given a point on the plane's 2D coordinate system, convert it back into a 3D point.
@param origin (Input) Point that defines the 2D coordinate system's origin.
@param axisX (Input) axis which defines the 2D x-axis
@param axisY (Input) axis which defines the 2D y-axis
@param A (Input) 2D point that is to be converted
@param output (Output) 3D point