*4.3. Effectiveness of Multi-Scale Sampling on Positive Sample*

To evaluate the effectiveness of Multi-scale sampling for positive samples, the comparison of positive samples distribution on different scales between multi-scale and origin FPN sampling method on DOTA dataset, the result are shown in Figure 6. Since the IOU discrimination thresholds of small and medium objects are reduced, the amount positive samples are highly improved, which means more small anchor boxes are matched. The matching results are also visualized, compare to Figure 7 the matching results has been effectively improved.

**Figure 6.** Distribution of multi-scale sampling and origin FPN sampling method.

**Figure 7.** Example of Multi-scale Sampling Results.
