All the contents superimposed or covered to the map are collectively referred to as map covers. Such as labels, vector graphic elements (including polylines, polygons, circles, etc.), positioning icons, etc. Covers have their own geographical coordinates. When you drag or zoom the map, they will move accordingly.

The basic maps and various coverage elements provided by Baidu Maps SDK for developers have a certain level of coverage, as follows (from top to bottom):

1. Custom View;

2. Pop up window layer;

3. Positioning layer;

4. Compass layer (when the map rotates and the view angle changes, the compass appears in the upper left corner by default);

5. Mark layer;

6. Geometry layer (point, polyline, arc, circle, polygon);

7. Bottom map annotation (refers to those POI elements attached to the bottom map);

8. Baidu Urban Thermal Map;

9. Real time road map layer;

10. Heat Map;

11. Topographic map layer (GroundOverlay);

12. TileOverlay;

13. Foundation base map (including base map, base map road, satellite map, indoor map, etc.);