calib3d: add CALIB_FIX_TANGENT_DIST flag

modules/calib3d/include/opencv2/calib3d.hpp

@@ -268,6 +268,7 @@ enum { CALIB_USE_INTRINSIC_GUESS = 0x00001,
        CALIB_TILTED_MODEL        = 0x40000,
        CALIB_FIX_TAUX_TAUY       = 0x80000,
        CALIB_USE_QR              = 0x100000, //!< use QR instead of SVD decomposition for solving. Faster but potentially less precise
+       CALIB_FIX_TANGENT_DIST    = 0x200000,
        // only for stereo
        CALIB_FIX_INTRINSIC       = 0x00100,
        CALIB_SAME_FOCAL_LENGTH   = 0x00200,

modules/calib3d/src/calibration.cpp

@@ -1516,6 +1516,8 @@ static double cvCalibrateCamera2Internal( const CvMat* objectPoints,
 
     mask[ 4] = !(flags & CALIB_FIX_K1);
     mask[ 5] = !(flags & CALIB_FIX_K2);
+    mask[6]  =
+    mask[7]  = !(flags & CALIB_FIX_TANGENT_DIST);
     mask[ 8] = !(flags & CALIB_FIX_K3);
     mask[ 9] = !(flags & CALIB_FIX_K4);
     mask[10] = !(flags & CALIB_FIX_K5);