# Open-Pit Map: An HD Map Data Model for Open-Pit Mines
## 4 Layer Information and Visualization of the HD Map  
This section will elucidate the layer information of the HD map for open-pit mines and the MapViewer, a map visualization tool developed based on this model. It allows for the reading and editing of the HD map. The mining data was obtained from the Jurong cement mine in Zhenjiang City, Jiangsu Province, China, which is primarily involved in the extraction of limestone for cement production. The mining scene is depicted in Figure 6. The visualization tool was developed based on Python, and the HD map data exchange specification was designed based on this model, which was defined as an mmp data file. Currently, its primary functions include reading data files, categorized display, distance measurement, information presentation, and so on. Figure 7 shows the HD map for the open-pit mine established within the software.  
Figure 5: UML class diagram of Location data structures.  
The geometric representation elements in the figure consist of eight primary components, including roads (Road), lanes (Lane), location areas (Location), blast areas (Blast), marking polygons (MarkPolygon), marking lines (MarkLine), traffic signals (Signal), and road intersections (Junction). Different geometric elements are represented using different colors. To provide a clearer description of the geometric structures within each part of the HD map, Figure 8a-c displays enlarged details of specific regions.  
Figure 8: Geometric representation of the elements of an HD map and local path topology. (**a**) Traffic elements. (**b**) Open-pit mining elements. (**c**) Geometric point sets. (**d**) Road network topology diagram.  
Figure 6: Jurong cement mine.  
Figure 7: MapViewer visualisation of HD map for open-pit mines.  
The geometric representation of elements within the established open-pit mining scene comprises points and lines. Points are the fundamental elements in the map that carry three-dimensional positional information, and all other elements are directly or indirectly composed of points. Geometric point sets are connected to create the geometric boundaries and extents of various elements within the map. Individual geometric points within the map hold special significance, serving as reference points within the network for tasks such as path planning and scheduling optimization. These points are categorized into three types: operation points, control points, and road endpoints. Operation points include loading points, unloading points, shift change points, maintenance points, fueling points, and rest points, representing the locations for production operations within the open-pit mine. Entrance points and exit points are special operation points, often associated with a specific production operation point. Control points are typically located at road intersections and trigger corresponding actions when vehicle routes change. Road endpoints are points at the beginning and end of road segments.  
The topological relationships among all the location points in the road network form the paths within the open-pit mining scene. A localized road network topology diagram is shown in Figure 8d. The routes formed between operational points are production paths, and multiple production paths can combine to create a production circuit. The routes formed between all location points can be established as a route map based on traffic rules and determine the specific routes to be traveled.