fix for 1-camera and stereocalib

modules/ccalib/src/omnidir.cpp

@@ -1782,13 +1782,15 @@ void cv::omnidir::internal::estimateUncertainties(InputArrayOfArrays objectPoint
 
     Mat sigma_x;
     meanStdDev(reprojError.reshape(1,1), noArray(), sigma_x);
-    sigma_x *= sqrt(2.0*(double)reprojError.total()/(2.0*(double)reprojError.total() - 1.0));
-    double s = sigma_x.at<double>(0);
 
     Mat _JTJ_inv, _JTE;
     computeJacobian(objectPoints, imagePoints, parameters, _JTJ_inv, _JTE, flags, 0.0);
     sqrt(_JTJ_inv, _JTJ_inv);
 
+    int nParams = _JTJ_inv.rows;
+    sigma_x *= sqrt(2.0*(double)reprojError.total()/(2.0*(double)reprojError.total() - nParams));
+    double s = sigma_x.at<double>(0);
+
     errors = 3 * s * _JTJ_inv.diag();
 
     rms = 0;
@@ -1868,13 +1870,15 @@ void cv::omnidir::internal::estimateUncertaintiesStereo(InputArrayOfArrays objec
 
     Mat sigma_x;
     meanStdDev(reprojErrorAll.reshape(1,1), noArray(), sigma_x);
-    sigma_x *= sqrt(2.0*(double)reprojErrorAll.total()/(2.0*(double)reprojErrorAll.total() - 1.0));
-    double s = sigma_x.at<double>(0);
 
     Mat _JTJ_inv, _JTE;
     computeJacobianStereo(objectPoints, imagePoints1, imagePoints2, _parameters, _JTJ_inv, _JTE, flags, 0.0);
     cv::sqrt(_JTJ_inv, _JTJ_inv);
 
+    int nParams = _JTJ_inv.rows;
+    sigma_x *= sqrt(2.0*(double)reprojErrorAll.total()/(2.0*(double)reprojErrorAll.total() - nParams));
+    double s = sigma_x.at<double>(0);
+
     errors = 3 * s * _JTJ_inv.diag();
 
     rms = 0;