calibrateCamera: specifiy what kind of re-projection error is returned

modules/calib3d/include/opencv2/calib3d.hpp

@@ -784,7 +784,7 @@ space, that is, a real position of the calibration pattern in the k-th pattern v
 @param stdDeviationsExtrinsics Output vector of standard deviations estimated for extrinsic parameters.
  Order of deviations values: \f$(R_1, T_1, \dotsc , R_M, T_M)\f$ where M is number of pattern views,
  \f$R_i, T_i\f$ are concatenated 1x3 vectors.
- @param perViewErrors Output vector of average re-projection errors estimated for each pattern view.
+ @param perViewErrors Output vector of the RMS re-projection error estimated for each pattern view.
 @param flags Different flags that may be zero or a combination of the following values:
 -   **CV_CALIB_USE_INTRINSIC_GUESS** cameraMatrix contains valid initial values of
 fx, fy, cx, cy that are optimized further. Otherwise, (cx, cy) is initially set to the image
@@ -823,6 +823,8 @@ the optimization. If CV_CALIB_USE_INTRINSIC_GUESS is set, the coefficient from t
 supplied distCoeffs matrix is used. Otherwise, it is set to 0.
 @param criteria Termination criteria for the iterative optimization algorithm.
 
+@return the overall RMS re-projection error.
+
 The function estimates the intrinsic camera parameters and extrinsic parameters for each of the
 views. The algorithm is based on @cite Zhang2000 and @cite BouguetMCT . The coordinates of 3D object
 points and their corresponding 2D projections in each view must be specified. That may be achieved
@@ -847,8 +849,6 @@ The algorithm performs the following steps:
     the projected (using the current estimates for camera parameters and the poses) object points
     objectPoints. See projectPoints for details.
 
-The function returns the final re-projection error.
-
 @note
    If you use a non-square (=non-NxN) grid and findChessboardCorners for calibration, and
     calibrateCamera returns bad values (zero distortion coefficients, an image center very far from