1. Single person registration video: Each person collects three videos: wearing a mask, half-wearing a mask, and not wearing a mask. 2. 300 people are randomly grouped into about 20 groups of 10-20 people. Each group is filmed for 5-10 minutes in the following 2 scenes, with each camera collecting 3 videos, for wearing a mask, half-wearing a mask, and not wearing a mask, respectively. Multi-person different scene videos: 6 cameras in entrance scene, 2 cameras in indoor dim light scene.