# An Indoor Space Model of Building Considering Multi-Type Segmentation
## 2 Conceptual Framework of Multi-Level Indoor Space Model
### Semantic Framework of Multi-Level Indoor Space  
The research of the indoor space data model follows the principles of geographic space cognition and segmentation methods and treats indoor spaces of different scales as specific functional, hierarchically nested complexes. This paper divides indoor space objects into five levels: building space, floor space, household space, room space, and functional subspace according to different abstract levels, and provides related definitions and descriptions, as shown in Table 1.  
Building spaceA building space is a place that has a certain structure and provides shelter for residents or internal things. It is located at the top of the indoor scene, including the above-ground and underground spaces, divided by building components. According to the purpose of the building, the space types of the building can be divided into residential, industrial storage and transportation, commercial and financial information, education, medical and health research, entertainment, military, and others [34]. According to the specific use function, the type of building space can be further divided. For example, houses can be divided into complete sets of residential buildings, non-sets of residential buildings, and collective dormitory buildings. Floor spaceFloor space is a number of sub-areas obtained by dividing the building space in the vertical direction. Floor space is the object used to organize the household space and the single indoor space. It is the second-level indoor space, including several household spaces or directly composed of all the room spaces on the same floor. Floors include standard floor, natural floor, equipment floor, false floor, mezzanine, attic, overhead floor, structural conversion floor, refuge floor, basement floor, and semi-basement. The standard floor is the floor with the same plane structure layout. The equipment floor is the space floor of the building dedicated to setting HVAC, air conditioning, water supply and drainage, electrical and other services indoor equipment. The overhead \begin{table}
\begin{tabular}{c c c} \hline \hline
**Level** & **Name** & **Define** & **Illustrates** \\ \hline \multirow{3}{*}{1} & \multirow{3}{*}{Building space} & A place with a certain structure that provides shelter for residents or internal things \\ \cline{3-3}  & & In the vertical direction, the number of sub-regions divided into the building space \\ \hline \multirow{3}{*}{2} & \multirow{3}{*}{Floor space} & A set of room spaces with the same users \\ \cline{3-3}  & & The internal space area of the building formed by the boundaries of walls, columns, floors, virtual components, etc. \\ \hline \multirow{3}{*}{5} & \multirow{3}{*}{Functional subspace} & Indoor functional area formed by dividing a single room space with indoor components such as screens and furniture \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Hierarchical level of indoor space. floor is an open space floor with only a supporting structure but no enclosure structure. When the building is more than 100 m high, refuge floors need to be set to ensure fire safety [35]. The basement floor is generally the floor where the indoor ground level is lower than the outdoor height and exceeds 1/2 of the indoor net height. 3. Household space  
A household space is a set of room spaces with the same users. It is usually used to organize a family or group by aggregating a set of spaces with specific functional combinations. Each household space must belong to a certain floor or building, and cannot be independent of the floor or building space. In addition to referring to the private housing tenants, the household space also includes the indoor space formed by the aggregation of common areas other than the housing households on the first floor. 4. Room space  
Room space is the internal space area of the building surrounded by boundary components such as walls, columns, floors, virtual components, etc. It is the fourth-level indoor space and is composed of several functional sub-spaces.