# Research on Driving Scenario Knowledge Graphs
## 3 Methodology: DSKG Construction
### Construction of Ontology for Driving Scenarios
#### 3.2.3 Definition of Class Relationships  
Based on the framework of the driving scenario domain ontology, the parent-child relationships of the hierarchical concepts of driving scenarios can be clearly defined. These relationships have transitivity, where subclasses can inherit parent class relationships and may also possess new specific relationships. Therefore, parent class relationships can be defined as common attributes, while subclass relationships are defined as specific relationships. The construction of conceptual relationships between classes in the driving scenario domain adopts a top-down approach. The ontology relationships describe the spatial, temporal, and semantic relationships between entities in traffic scenarios, as shown in Table 4.  
To illustrate the hierarchical structure and associative relationships of the domain ontology further, we utilized the OntoGraf module of the Protege for visualization. The complete ontology is shown in Figure 5. In the figure, solid lines represent the hierarchical relationships of the ontology, while dashed lines illustrate the associations between concept classes.  
\begin{table}
\begin{tabular}{p{85.4 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Relationship Category** & **Meaning** & **Examples** \\ \hline \multirow{6}{*}{Spatial Relationship} & Describes the topological, directional, and metric relationships between concept classes. & The position dependency between lanes, road irregularities, and roadside facilities. \\ \cline{3-4}  & & The positional relationship between the driving direction of the vehicle and dynamic objects such as vehicles and pedestrians. \\ \cline{3-4}  & & The relative distance between the vehicle and roadside facilities, dynamic objects, and other elements. \\ \hline \multirow{6}{*}{Temporal Relationship} & Describes the geometric topology information of time points or timelines between concept classes. & Whether the vehicle passes through the intersection during the green light phase of the traffic signal. \\ \cline{3-4}  & & Changes in environmental conditions over time during vehicle travel. \\ \cline{3-4}  & & The duration of vehicle parking in temporary parking areas. \\ \hline \multirow{6}{*}{Semantic Relationship} & Describes the traffic connections between concept classes to express accessibility or restrictions, subject to constraints of time and space. & The relationship between people and vehicles in terms of driving or being driven. \\ \cline{3-4}  & & The relationship between people and vehicles in terms of driving or being driven. \\ \hline \hline \end{tabular}
\end{table}
Table 4: Example of relationships in the driving scenario domain.  
\begin{table}
\begin{tabular}{p{85.4 pt} p{113.8 pt}} \hline \hline
**Classes** & **Attributes** \\ \hline Lane & Length, width, direction, type, speed limit, etc. \\ Traffic markings & Type, color, width, length, shape, maintenance status, etc. \\ Vehicle & Type, brand, color, driving status, etc. \\ Person & Age group, gender, activity status, etc. \\ Object & Type, size, color, material, shape, mobility, etc. \\ \hline \hline \end{tabular}
\end{table}
Table 3: Example of concept class properties in the driving scenario domain.