hack solvePoly to finds roots of polynoms with zero higher-order coefficients. The roots are populated in this case, which is not valid, strictly speaking, but good enough for function like correctMatches. This solves http://code.opencv.org/issues/4330

modules/calib3d/test/test_fundam.cpp

@@ -1709,4 +1709,21 @@ TEST(Calib3d_ConvertHomogeneoous, accuracy) { CV_ConvertHomogeneousTest test; te
 TEST(Calib3d_ComputeEpilines, accuracy) { CV_ComputeEpilinesTest test; test.safe_run(); }
 TEST(Calib3d_FindEssentialMat, accuracy) { CV_EssentialMatTest test; test.safe_run(); }
 
+TEST(Calib3d_FindFundamentalMat, correctMatches)
+{
+    double fdata[] = {0, 0, 0, 0, 0, -1, 0, 1, 0};
+    double p1data[] = {200, 0, 1};
+    double p2data[] = {170, 0, 1};
+
+    Mat F(3, 3, CV_64F, fdata);
+    Mat p1(1, 1, CV_64FC2, p1data);
+    Mat p2(1, 1, CV_64FC2, p2data);
+    Mat np1, np2;
+
+    correctMatches(F, p1, p2, np1, np2);
+
+    cout << np1 << endl;
+    cout << np2 << endl;
+}
+
 /* End of file. */

modules/core/src/mathfuncs.cpp

@@ -2047,7 +2047,7 @@ double cv::solvePoly( InputArray _coeffs0, OutputArray _roots0, int maxIters )
     CV_Assert( CV_MAT_DEPTH(ctype) >= CV_32F && CV_MAT_CN(ctype) <= 2 );
     CV_Assert( coeffs0.rows == 1 || coeffs0.cols == 1 );
 
-    int n = coeffs0.cols + coeffs0.rows - 2;
+    int n0 = coeffs0.cols + coeffs0.rows - 2, n = n0;
 
     _roots0.create(n, 1, CV_MAKETYPE(cdepth, 2), -1, true, _OutputArray::DEPTH_MASK_FLT);
     Mat roots0 = _roots0.getMat();
@@ -2063,6 +2063,12 @@ double cv::solvePoly( InputArray _coeffs0, OutputArray _roots0, int maxIters )
             coeffs[i] = C(rcoeffs[i], 0);
     }
 
+    for( ; n > 1; n-- )
+    {
+        if( std::abs(coeffs[n].re) + std::abs(coeffs[n].im) > DBL_EPSILON )
+            break;
+    }
+
     C p(1, 0), r(1, 1);
 
     for( i = 0; i < n; i++ )
@@ -2100,6 +2106,9 @@ double cv::solvePoly( InputArray _coeffs0, OutputArray _roots0, int maxIters )
                 roots[i].im = 0;
     }
 
+    for( ; n < n0; n++ )
+        roots[n+1] = roots[n];
+
     Mat(roots0.size(), CV_64FC2, roots).convertTo(roots0, roots0.type());
     return maxDiff;
 }