Figure 9.

Example with two ground truth instance locations (solid circles connected with black lines) and two detected instances (empty circles connected with white lines) using matching results achieved with both the Hungarian algorithm and the proposed cross-check matching of Equations (9) and (10). While the detection x and ground truth location b in the middle are clearly nearest neighbors of one another, they are not matched by the Hungarian algorithm. Instead, in an effort to minimize the global matching cost, the Hungarian algorithm will assign a to x and b to y. In contrast, the cross-check matching method leaves the outer detection y and ground truth location a unmatched while assigning the two in the middle, x and b, together.