  We will make a brief introduction of the experimental methods and results of
the WHU-NERCMS in the TRECVID2021 in the paper. This year we participate in the
automatic and interactive tasks of Instance Search (INS). For the automatic
task, the retrieval target is divided into two parts, person retrieval, and
action retrieval. We adopt a two-stage method including face detection and face
recognition for person retrieval and two kinds of action detection methods
consisting of three frame-based human-object interaction detection methods and
two video-based general action detection methods for action retrieval. After
that, the person retrieval results and action retrieval results are fused to
initialize the result ranking lists. In addition, we make attempts to use
complementary methods to further improve search performance. For interactive
tasks, we test two different interaction strategies on the fusion results. We
submit 4 runs for automatic and interactive tasks respectively. The
introduction of each run is shown in Table 1. The official evaluations show
that the proposed strategies rank 1st in both automatic and interactive tracks.
