# An Indoor Space Model of Building Considering Multi-Type Segmentation
## 2 Conceptual Framework of Multi-Level Indoor Space Model
### Multi-Type Segmentation of Indoor Space  
The interior scene of a building can be divided into two parts: component and space. The boundary of space is defined by the component, and the component is in the space. Two parts are the premise of each other and coexist in unity. From the perspective of indoor space cognition, the essential difference between space and component is that component will block people's line of sight or route, while space will ensure an unobstructed line of sight. When people are active in indoor space, they first pay attention to the differences between components and space, and mainly guide them to avoid components through sight. This guiding rule determines the scope and path of people's activity in the free indoor space. In space syntax, line-of-sight accessibility analysis is usually used to express whether there is occlusion of the line of sight between two points in space. Therefore, in the process of cognition of indoor space, firstly pay attention to the sight accessibility  
Figure 1: Indoor space and segmentation components. of the space, and use components to divide the space into subspaces. However, due to the different visibility and mobility of components, the segmentation intensity of indoor space is also different. As shown in Figure 2, according to the characteristics of component entities from strong to weak, this paper divides the segmentation type of indoor space into the following four types:  
1. Segmentation of load-bearing building components (Figure 2(1))  
The load-bearing components of the building mainly include structural components such as a load-bearing wall, load-bearing column, floor, beam, and so on. The load-bearing structural components not only directly bear various external forces of the building, but also play a role in enclosing the indoor space to a certain extent. Once the segmentation is completed, it is permanent and cannot be changed. Therefore, the division of the load-bearing components is the first-level division. 2. Segmentation of common building components (Figure 2(2))  
An indoor space is enclosed by ordinary building components and load-bearing structural components. Ordinary walls are used to completely block the external line of sight, sound, and light, forming an independent indoor space with good privacy. However, these walls can be removed and changed. The division of the non-load bearing ordinary building components is the second-level division. 3. Segmentation of furniture solid components (Figure 2(3))  
Every piece of furniture should be used to divide the empty interior space of the room. The segmentation of indoor space by furniture entities can be divided into vertical division and horizontal division. Vertical division refers to the use of furniture to subdivide the indoor space in a vertical direction. The division entities mainly include partitions, screens, furniture, and other components. As shown in Figure 3, partitions refer to the facades that are used to separate indoor spaces. They are more flexible in application, including fixed partitions and movable partitions. As an important part of traditional furniture, screens are placed indoors to block the wind and line of sight, which also plays a role in dividing the indoor space. The indoor space is divided by transparent high cabinets, shelves, etc., and the lines of sight can see through each other, emphasizing the fluidity and connectivity between adjacent indoor subspaces. Figure 2: The four segmentation types of indoor space based on components (1–4). Horizontal segmentation refers to the subdivision of the indoor space in the horizontal direction. This segmentation mostly uses relatively short furniture, such as sofas, counters, tables, and chairs. These items of furniture usually occupy a certain space on the horizontal plane, by themselves or in combination with other furniture, forming a functional area with a specific boundary in the indoor space.