At present, urbanization is accelerating globally (
UN, 2007;
Liu and Li, 2017). Urban spatial expansion, as an important aspect of the urbanization process, has always been a hot topic globally in the fields of urban geography, urban planning and urban land use research (
Anas, 1976;
Liu et al., 2016;
Wen et al., 2016). China entered a period of rapid urbanization from the 1990s (
Chi et al., 2015); a large number of cities have expanded rapidly, with city sizes reaching the largest scale ever in human history (
Wang et al., 2012; Zhao
et al., 2012), and will continue to expand. Many scholars have analyzed urban land expansion, morphology evolution (
Chen et al., 2016a), and the evolution of land use structure by examining expansion strength (
Xu and Min, 2013), compactness (
Yin et al., 2010), fractal dimension (
Liu et al., 2016), shape index (
Wang et al., 2015), gravity-center model (
Maimaiti et al., 2017;
Yang et al., 2018), landscape index (
Quan et al., 2015;
Triantakonstantis and Stathakis, 2015), equivalent fan analysis (
Zhang et al., 2016), transfer matrix (
Kumar and Tripathi, 2014) etc. from a two-dimensional perspective. However, urban spatial expansion is reflected not only in the two-dimensional growth of the city but also in the increase of its vertical height. In recent years, in China’s economically developed areas, with the rapid expansion of cities land space has been very limited. This requires that urban spatial expansion be changed from being extensive to being intensive, focusing on improving land use intensity in urban built-up areas (
Liu et al., 2014). Therefore, the trend of three-dimensional spatial expansion in large and medium-sized cities has become increasingly discernible (
Liu and Chen, 2001;
Gruen, 1998). Statistically, by the end of 2012, China included 5 of the top 10 cities in the world with the highest number of high-rise buildings over 24 m (8 floors). From the perspective of the spatial organization of urban land use, urban space is three-dimensional, and three-dimensional spatial expansion is mainly reflected in the increase of building height and land plot ratio (
Sun et al., 2002). However, despite the constant increase of urban building heights and the increasing contribution of vertical extension to urban volume growth, most studies have only analyzed urban morphology evolution and spatial expansion from a two-dimensional perspective, ignoring the city’s vertical stretch and land use intensity change. This, to a certain extent, affects the understanding of the evolution of the urban spatial form as well as land use change laws. To comprehensively grasp the laws of urban spatial expansion and to promote scientific decision-making for urban planning and urban land use management, this paper considers the urban land use system as a whole, based on a multi-dimensional perspective (taking both two and three dimensions into account), and comprehensively analyzes urban spatial expansion using RS and GIS technology. To study urban expansion from a multi-dimensional perspective, multi-phase urban three-dimensional models must be constructed first. Most of the construction methods are to extract the roof profiles and building heights in different periods through high-resolution remote sensing images. Some literatures have studied the methods of extracting building height and floor area ratio information using remote sensing images (
Weidner and Förstner, 1995;
Seresht and Azizi, 2000;
McIntosh and Krupnik, 2002), but the extraction accuracy and efficiency need to be improved. Based on the improvement of the above extraction method, this paper proposes the research method of multi-dimensional expansion of urban space (MEUS), and then conducts multi-angle study on MEUS.