code: public static CameraPinholeBrown createIntrinsic(int width, int height, double hfov) {
  		CameraPinholeBrown intrinsic = new CameraPinholeBrown();
  		intrinsic.width = width;
  		intrinsic.height = height;
  		intrinsic.cx = width / 2;
  		intrinsic.cy = height / 2;
  		intrinsic.fx = intrinsic.cx / Math.tan(UtilAngle.degreeToRadian(hfov/2.0));
  		intrinsic.fy = intrinsic.fx;
  
  		return intrinsic;
  	}
docs: Creates a set of intrinsic parameters, without distortion, for a camera with the specified characteristics.
  The focal length is assumed to be the same for x and y.
  
  @param width Image width
  @param height Image height
  @param hfov Horizontal FOV in degrees
  @return guess camera parameters