Start from the fitness gym model (free sign-up), or draw your own gym. In a 24-hour gym with no staff at night, the security cameras watch the entrance, the reception and the training floor, and must not film inside the changing rooms or the toilet. In this article your AI works out, on a gym model, how many cameras are needed, where they go, how much they cover and whether they can see into the changing rooms, using the same tools an AI calls over MCP. Every figure and picture below comes from those tools.
1. What was done
- The model is a gym of 20.4 × 16.4 m with a 3.2 m ceiling: the men's and women's changing rooms (with showers) on the west side, the lobby, the reception and a toilet in the south-west corner, and the training floor (eight treadmills, three exercise bikes and eight strength machines). The changing rooms' doors open onto the training floor.
- What must be covered: the entrance and 2 m around it, the reception and 1.5 m around it (each counted three times), and the training floor. No camera goes in the changing rooms or the toilet.
- Two kinds of camera (their specifications are assumed): an ordinary camera on a wall, 2.6 m up (90° across, 60° up and down, a range of 20 m), and an all-round camera on the ceiling, 3.1 m up, looking straight down (360°, a range of 10 m).
- With
suggest_camerasthe AI looked for positions for up to six cameras of each kind, placed four of the kind that covers more, and measured how much of the changing rooms and the toilet the cameras see with their doors open and with them shut.
2. Coverage by number of cameras
| Cameras | Ordinary cameras on the walls | All-round cameras on the ceiling |
|---|---|---|
| 1 | 79.2% | 84.6% |
| 2 | 89.1% | 90.7% |
| 3 | 93.1% | 95.2% |
| 4 | 95.5% | 96.0% |
| 5 | 97.1% | 96.6% |
| 6 | 98.0% | 97.1% |
(Shares of what must be covered, with the entrance and the reception counted three times; the floor to be covered is 201.88 m².)
- Up to four cameras, the ceiling covers more; from five, the walls do. With few cameras the all-round cameras on the ceiling cover more; from five cameras, the ordinary cameras on the walls cover more.
- With the four cameras on the ceiling, 100.0% of the area around the entrance, 91.2% around the reception and 97.2% of the training floor are covered.
3. Can the cameras see into the changing rooms and the toilet?
| Room | Doors open | Doors shut |
|---|---|---|
| Men's changing room (32.56 m²) | 1.44 m² (4.4%) | 0 m² |
| Women's changing room (32.94 m²) | 7.56 m² (23.0%) | 0 m² |
| Toilet (3.19 m²) | 0.38 m² (11.8%) | 0 m² |
- With a door open, the floor beyond it is visible. No camera is in the changing rooms or the toilet, but the cameras on the ceiling of the training floor and the lobby see the floor inside through the open doors: 7.56 m² of the women's changing room.
- With the doors shut, 0%. Keep the changing rooms' doors shut (doors that close by themselves, for example), and check that nothing inside is visible from in front of the doors.
4. How to use it, and what it does not know
- Draw walls as walls unless they are glass. This model's changing room walls were first drawn as glass partitions, and the cameras seemed to see inside with the doors shut. They were made walls before counting. When you draw your own gym, draw walls that cannot be seen through with the wall part.
- Coverage is geometry only. It is counted from the field of view and the line of sight alone. Whether a face can be recognised depends on the camera's resolution, the distance and the angle. Give the AI the specifications of the cameras you use.
- Put up a notice. The Personal Information Protection Commission's Q&A (Q1-13, in Japanese) says that a security camera filming images that identify a person should be used within its purpose, specified as far as possible, and that where people cannot easily tell they are being filmed, a notice such as "security camera in operation" should be put up (Act on the Protection of Personal Information, Article 20(1)).
5. How to ask an AI
Find positions for four ceiling cameras in this gym, giving more weight to the entrance and reception. Keep cameras out of the changing rooms and toilet. Compare how much of the floor they see, and how much they see inside those rooms with the doors open and closed.
Tools used
suggest_cameras: what must be covered and where cameras go, and how much they see inside the changing rooms and the toiletedit_space: place the cameras as partsget_visibility: what the placed cameras seeget_view_image: the plan
