For (size_t m=0; M & lt; Matches12. The size (); M)
{
Bool findCrossCheck=false;
For (size_t fk1 - fk=0; Fk1 - fk & lt; Matches12 [m]. The size (); Fk++)
{
DMatch forward=matches12 [m] [fk1 - fk];

For (size_t bk=0; Bk & lt; Matches21 [forward trainIdx]. The size (); Bk++)
{
DMatch backward=matches21 [forward trainIdx] [bk];
If (backward. TrainIdx==forward. QueryIdx)
{
FilteredMatches12. Push_back (forward);
FindCrossCheck=true;
break;
}
}
If (findCrossCheck) break;
}
}
Below will appear Assert failed: the queries, cols==veclen<>
The vector out of range