temporarily use EPNP in SolvePnP instead of UPNP or DLS algorithms, since the latter two are not quite stable

modules/calib3d/perf/perf_pnp.cpp

@@ -64,7 +64,7 @@ PERF_TEST_P(PointsNum_Algo, solvePnP,
 
 PERF_TEST_P(PointsNum_Algo, solvePnPSmallPoints,
             testing::Combine(
-                testing::Values(4), //TODO: find why results on 4 points are too unstable
+                testing::Values(4),
                 testing::Values((int)SOLVEPNP_P3P, (int)SOLVEPNP_DLS, (int)SOLVEPNP_UPNP)
                 )
             )
@@ -92,7 +92,7 @@ PERF_TEST_P(PointsNum_Algo, solvePnPSmallPoints,
 
     //add noise
     Mat noise(1, (int)points2d.size(), CV_32FC2);
-    randu(noise, 0, 0.001);
+    randu(noise, -0.001, 0.001);
     add(points2d, noise, points2d);
 
     declare.in(points3d, points2d);

modules/calib3d/src/solvepnp.cpp

@@ -59,9 +59,9 @@ bool cv::solvePnP( InputArray _opoints, InputArray _ipoints,
     CV_Assert( npoints >= 0 && npoints == std::max(ipoints.checkVector(2, CV_32F), ipoints.checkVector(2, CV_64F)) );
     _rvec.create(3, 1, CV_64F);
     _tvec.create(3, 1, CV_64F);
-    Mat cameraMatrix = _cameraMatrix.getMat(), distCoeffs = _distCoeffs.getMat();
+    Mat cameraMatrix = Mat_<double>(_cameraMatrix.getMat()), distCoeffs = Mat_<double>(_distCoeffs.getMat());
 
-    if (flags == SOLVEPNP_EPNP)
+    if (flags == SOLVEPNP_EPNP || flags == SOLVEPNP_DLS || flags == SOLVEPNP_UPNP)
     {
         cv::Mat undistortedPoints;
         cv::undistortPoints(ipoints, undistortedPoints, cameraMatrix, distCoeffs);
@@ -95,7 +95,7 @@ bool cv::solvePnP( InputArray _opoints, InputArray _ipoints,
                                      &c_rvec, &c_tvec, useExtrinsicGuess );
         return true;
     }
-    else if (flags == SOLVEPNP_DLS)
+    /*else if (flags == SOLVEPNP_DLS)
     {
         cv::Mat undistortedPoints;
         cv::undistortPoints(ipoints, undistortedPoints, cameraMatrix, distCoeffs);
@@ -120,7 +120,7 @@ bool cv::solvePnP( InputArray _opoints, InputArray _ipoints,
         else
             cameraMatrix.at<double>(0,0) = cameraMatrix.at<double>(1,1) = f;
         return true;
-    }
+    }*/
     else
         CV_Error(CV_StsBadArg, "The flags argument must be one of SOLVEPNP_ITERATIVE, SOLVEPNP_P3P, SOLVEPNP_EPNP or SOLVEPNP_DLS");
     return false;