## 4 Results and Analysis
### Analysis of the Impact of Spatial Visual Elements on the Spatial Quality of Urban Streets  
We calculated the values of the five spatial metrics for each streetscape collection point using the formula shown in Part 3.4. Then, we tested the correlation between the six perception scores and the five primary spatial metrics. The results showed that all the factors were significantly correlated, meaning that linear regression analyses could continue. The regression analysis results are shown in Figure 7, where the lines of different colors represent the influence coefficients of the five spatial measures under the spatial perception of different streets. The longer the lines of color in the bar graph, the higher the absolute value of the standardized beta coefficient. Firstly, the respective factors under the six perceptions were compared and analyzed. Under the boring perception category, all five spatial metrics had a negative impact on the boredom score. Still, the degree of influence varied, with the green visual index having a significantly higher negative impact than the other categories, followed by the degree of enclosure and the sky visibility index. The degree of non-motorization had a more negligible, albeit still negative, impact. In the beautiful perception study, the green visual index and the sky visibility index had the most significant positive effects. Sky and plant visibility were essential for building a beautiful ecological and visual environment that is conducive to enhancing the spatial experience of pedestrians. Thus, these two factors were more critical for pedestrians' perceptions of space. The degree of non-motorization had a negative influence, and it can be presumed that people's perception of the beautification of the street space was hindered by people or bicycles. For the depressing perception, the higher the degree of enclosure and motorization, the more depressing the urban street space. However, sky and green visibility had a significant adverse effect on the perception of pedestrian depressiveness, necessitating a focus on these elements in the discussion of the design methods used to reduce the depressiveness of urban street space. All five spatial measures positively impact the lively feeling of street space. Still, the degree of enclosure, sky visibility index, and green visual index have a significantly higher impact than the other two indicators. The degree of enclosure is often closely related to the height and density of the surrounding buildings, which indicates that the closer the area with a high perception of urban liveliness value is, the higher the density and height of buildings tend to be. The perception of a lively core correlates with an area's prosperity. The degree of enclosure, green visual index, and sky visibility index significantly positively affect the perception of safety. However, due to the negative impact of motorization on safety perception, one way to improve security is to reduce the occurrence rate of motor vehicles. Under the influence of affluence, the degree of enclosure and sky visibility index have a more crucial impact, and the degree of non-motorization plays a negative role. Overall, the green visual index, sky visibility index, and degree of enclosure greatly influence each aspect of perception, providing clear guidance for the research strategy of quality improvement in terms of the spatial dimension of urban streets.  
Figure 7: Histogram of the beta coefficient of the regression analysis.