Three-dimensional characterization and calculation of highway space visual perception

To quantify the impact of three-dimensional highway spatial characteristics on drivers' visual perception, this study analyzes the measurement points of highway spatial visual perception from the perspectives of spatial visual depression and spatial visual continuity based on spatial perception theory. Based on the hemispherical field of view, a spatial enclosure calculation method improved by "Distance/Height value" is proposed. A three-dimensional quantification model of the build-to-line ratio, including the vertical direction, was established using the relative relationship between the maximum section plane and the road area. Finally, a 3D real-scene model of the demonstration highway section was established, the proposed three-dimensional quantization method of visual perception of highway space was applied, and the road area landscape construction and promotion strategy is proposed based on the quantitative calculation results. The results show that: the overall landscape space of the highway section is undulating and that there is a lack of visual continuity. It is advisable to plant an appropriate amount of vegetation on the side of the road at 0 m–250 m and 500 m–700 m of the road section to reduce the fluctuation of its enclosure and enhance its spatial continuity. The improved quantitative results of the spatial enclosure degree and the three-dimensional build-to-line ratio can well characterize the spatial visual depression and the spatial visual continuity and can provide a basis and support for road space reorganization and the improvement of landscape construction.