Green space integrates diversified urban functions, and the analysis of its utilization, can help improve the vitality of the social and economic development of cities while contributing to the important goal of enhancing urban green space (UGS) planning and management. In this study, the heat value obtained from Baidu heat maps was used as an external representation of spatial vitality, and the factors that influence vitality were analyzed from two dimensions, i.e., the inner and outer space characteristics of green space, using spatial big data such as points of interest (POIs), Open Street Map (OSM) and online review data. The findings indicated that green space and urban resources in Chengdu are highly centralized. That is, a high road network density and nearby transportation facilities make it easier for visitors to reach parks, while peripheral functional density also plays a role in promoting vitality; additionally, reasonable and moderate space and functional layouts are conducive to the development of green space. In addition, our study integrates the tour experience index, which has a strong positive impact on vitality, to better reflect the human-oriented characteristics of green space, which are of great relevance to the construction and renewal of human space in UGSs.

Urban green space (UGS) is an important public infrastructure. However, the rapid development of cities and the insufficient supply and uneven distribution of UGSs have led to a mismatch between them and various needs, which has seriously affected environmental justice and social equity. This study discusses the fairness of UGS from the perspective of supply and demand and improves the theoretical framework of supply and demand combination evaluation. First, this study analyzes the supply of UGSs through accessibility analysis and evaluates their demand from both subjective and objective dimensions. Second, the fairness of UGS is analyzed from a Gini coefficient and spatial evaluation perspective. Finally, the location optimization of UGSs is performed, which provides strategic guidance for the improvement of UGSs in Chengdu. The research results based on Chengdu City show that the travel mode directly affects the supply range of UGSs and is reflected in their fairness. At the same time, in the case of a highly dense population, UGSs in the city are in short supply; that is, the equity is negatively correlated with the population. This study provides a new perspective to evaluate UGS fairness and can be a reference for UGS optimization decisions.