How does the Xiaomi Robot Vacuum S20+ save a complete map?

The way of the Xiaomi Robot Vacuum S20+ saving a complete map is shown below:
1. Before use, please open the door of the area to be cleaned to ensure the integrity of the map;
2. The robot vacuum supports fast map building. When used for the first time, after the Mi Home/Xiaomi Home APP is networked, use the fast map building function according to the novice guide. When the robot vacuum quickly builds a map, it will explore the home environment and only build a map without cleaning. The entire map building process takes about 5 to 15 minutes. After the map is built, the robot vacuum returns to the charging dock and can generate a recognized partition map;
3. If you press the button to start cleaning, the robot vacuum will start the cleaning task from the charging dock and return to the charging dock autonomously, and a complete partition map will also be generated;
4. If you manually recharge the robot vacuum or manually move it back to the charging dock during the process, it can only be generated as a temporary map. Temporary maps do not have automatic partitions, and functions such as partition adjustment or renaming cannot be used.