# Detecting Underground Geospatial Features for Protection of Rights in 3D Space: Korean Cases
## 4 Discussion
### Building Data on the Spatial Relation between Ground and Underground Space  
To register an underground space based on the store-level 3D underground space data generated using a survey or pre-built data, the spatial status of the ground and underground space needs to be evaluated. It is necessary to consider the rights relation between the above-ground and underground of the surface since land ownership in Korea is set around the surface. When using the above-ground and underground spaces of a parcel owned by others, compensation must be made accordingly. Moreover, if the space is under different administrative districts, it is advisable to check both the parcel boundaries and administrative district boundaries since the management parties will also be different.  
Therefore, in this study, the spatial status information of the underground and ground space was generated based on the generated 3D underground spatial data. First, to generate the current status information on the horizontal position as shown in Figure 7, we overlapped the underground space spatial data and the continuous cadastral map to analyze the consistency between the underground spatial object and the boundary on the surface (administrative zone boundary, above-ground parcel boundary). The underground shopping center is located in the underground of two administrative districts, as shown in Figure 7b, and one underground shopping store is located in the underground of two above-ground parcels, as shown in Figure 7c. Similarly, the spatial status information for the case where one shopping center or an individual store is located in the basement of  
Figure 6: 3D spatial data generation using VWorld data. (**a**) VWorld raw data. (**b**) Store unit object generation. (**c**) Attribute information input. (**d**) 3D modeling (3 DS).  
several administrative boundaries or parcels can be effectively utilized in terms of facility management and property rights protection.  
Next, the vertical location status information with the above-ground parcel was generated. The vertical position status information is extremely important information. It relates to the depth limits used to determine the need for compensation when using the underground space of a parcel owned by others. The depth limit refers to the depth at which the landowner is not expected to use the land. Hence, it is determined so that it does not hinder the use of the land below ground even if underground facilities are installed. However, such depth limits have not yet been established by law. In Seoul, the capital city of Korea, the ordinance stipulates a basement of 40 m for high-rise urban districts, 35 m for middle-rise, 30 m for low-rise and residential areas, and 20 m for farmland and forest areas. In this study, to generate vertical position status information of underground space objects, we built a digital elevation mode (DEM) using a 1:5000 numerical map to calculate the maximum and minimum depths from the above-ground parcel corresponding to the underground space, as shown in Figure 8. When the underground space object was located in the underground of several above-ground parcels (Figure 8a), the maximum and minimum depths from each parcel were extracted (Figure 8b) to protect the property rights of all parcels.