Objective As one of the most scarce landscape resources in cities, the coastal shoreline endows urban coastal spaces with unique ecological and landscape conditions. Meanwhile, with the development of the social economy, the expansion of urban fringes, and the improvement of living standards, coastal spaces are playing an increasingly important role in urban development. However, due to the influence of location, form, and landscape, problems such as insufficient human presence, seasonal differences, and limited radiation range in the vitality of coastal spaces have gradually emerged during the urbanization process. How to improve the quality of coastal spaces and enhance their vitality has become a widely concerned issue in both academic and industrial circles.

Methods To address this issue, this research constructs a digital portrait of different crowds in coastal spaces based on the analysis of the evaluation dimensions of the vitality of coastal spaces. The digital portrait is created through four dimensions: basic attributes, socio-economic status, travel purposes, and lifestyle. By analyzing the spatial distribution of stay points and the spatio-temporal patterns of travel trajectories of each typical crowd at different times, the vitality of coastal spaces for each crowd is further analyzed, including the attractiveness of coastal spaces to various crowds, as well as the capacity and transportation accessibility of coastal spaces. Then, through field research, questionnaire interviews, and spatial simulation analysis, the root causes of relevant problems are identified. Finally, based on the behavioral trajectories and spatio-temporal vitality differences of different crowds, optimization strategies for the spatial layout of coastal spaces are proposed. In contrast to traditional approaches, the analysis of coastal space vitality grounded in the digital profiling of crowds enables the screening of key subjects from a vast and intricate crowd. It can also pinpoint the core issues in a targeted manner, thereby effectively enhancing the vitality and quality of coastal spaces. Ultimately, by taking into account the behavioral trajectories of each crowd and their vitality variances across different time intervals, optimization strategies for traffic guidance and spatial layout within coastal spaces are put forward. Additionally, integrating the spatial distribution of crowd stop points and crowd categories, the morphological structure and spatial nodes are optimized and upgraded.

Results Taking the coastal space of Jiulong Bay in Weihai as an example, this research selects 18 typical crowds with the largest proportion to construct a crowd digital portrait. The research finds that the crux of the vitality issue of coastal spaces lies in three aspects: First, the closed layout and spatial fragmentation prevent people from traveling to coastal spaces; second, the lagging infrastructure construction makes it difficult for people to stay in coastal spaces; third, the long and narrow transportation system makes it difficult to disperse people in coastal spaces. In response to these three problems, this research proposes design strategies such as attracting recreation, inhibiting pass-through, promoting the integration and sharing of diverse crowds, and optimizing the form of green space nodes.

Conclusion The crowd digital portrait proposed in this research as a digital means of analyzing crowd activities, has the characteristic of deeply depicting and classifying the age and gender composition, behavioral purposes, activity methods, and trajectory patterns of the crowds in coastal spaces based on their geographical location, transportation environment, and landscape characteristics. It can help understand the vitality characteristics and spatio-temporal patterns of coastal spaces, and then, in combination with the form of coastal spaces, identify the crux of problems such as insufficient human presence and uneven vitality, and propose corresponding strategies.