## 2 Driver Road Performance Assessment Model
### Driver Perception Capability Assessment  
The first stage of driver assessment quantitatively assesses the driver's environmental perception capability. This assessment is based on the area covered by the driver's field of view, which includes both the directly scanned area and the indirectly reflected area in the rear-view mirrors. The evaluation of a driver's environmental perception capability involves calculating the area within the driver's line of sight where their attention is focused. In accordance with pertinent research, we defined specific parameters for this assessment. We assumed that the driver's field of vision encompasses an angle of 60 degrees, with their attention span extending over a distance of 50 m (through consultations with internal experts from the Research Institute for Road Safety of MPS China). To streamline the computation of the field of vision in our practical vehicle application, we simplified the observed circular arc by dividing it into three triangular regions, as illustrated in Figure 2. This simplification was employed to reduce computational complexity, especially at the boundaries of the arc in radians. Figure 2a represents the driver's observation area, which takes the form of a circular arc. Figure 2b shows a simplified representation of the observation area. The gap between the first point and second point is 20 degrees, and between the central and second points it is 10 degrees. When a vehicle traverses an intersection, the driver's head undergoes rotational movements due to the act of observation, causing changes in the position and orientation of the simplified observation area. To calculate the area observed by the driver when entering the intersection scene, encompassing the stages prior to entering and being within the intersection, we devised a method to compute the intersection and union of polygons. Given that the aforementioned polygons are non-concave, we applied the Sutherland-Hodgman clipping algorithm to  
Figure 1: The RPAM overall structure. Figure 2: The simplified observed area. compute the intersection [8]. The union of the polygons was then determined by merging the results obtained from two iterations of the Sutherland-Hodgman algorithm, where the source and clipping polygons are exchanged [9]. Additionally, we determined the environmental perception capability score based on the observed area in relation to the total scene area. The area of an observed and overall polygon were then calculated using Equation (1), where (x, y) are the coordinates of the points on the outline of the region. \[Size_{polygon}=\frac{1}{2}|\sum_{i=1}^{i=n}(x_{i}y_{i+1}-x_{i+1}y_{i})| \tag{1}\]  
The driver score for the ability to observe can be calculated using Algorithm 1. \(n\) in the equation represents the number \(n\) vertex of the polygon. ```
if vehicle enters 'test start mark' then while not vehicle enters 'intersection mark' do  HeadOrientation \(\leftarrow\)\((HeadRotationAngle,VehicleHeading)\)  Polygon\({}_{P_{1}}\)\(\leftarrow\) HeadOrientation  Polygon\({}_{view}\)\(\leftarrow\) intersect\((Polygon_{P_{1}},Polygon_{road})\) if first frame then  continue else  Polygon\({}_{view}\)\(\leftarrow\)\(union(Polygon_{view},Polygon_{last})\) endif  Polygon\({}_{view}\)\(=\)\(Polygon_{last}\) endwhile  Size\({}_{view}\)\(\leftarrow\)\(Polygon_{view}\)  Size\({}_{road}\)\(\leftarrow\)\(Polygon_{road}\) ratio \(=\)\((Size_{view}/Size_{road})\) if\(ratio\)\(<=0.5\)then  Score \(=0\) else  Score \(=100*(ratio-0.5)/0.5\) endif  endif
```  
**Algorithm 1** Calculation of the observed assessment score  
We posit that drivers should complete their environmental observation before their vehicle formally enters an intersection; hence, the assessment of environmental perception capabilities will commence at the moment of entry into the testing scenario and conclude upon entry into the intersection. In the case of lane-changing scenarios, an observation is considered to be completed when the driver's field of vision scans the area where the rear-view mirror is located.