**1. Introduction**

Nearly all Chinese cities now have advanced from the stage of incremental development to the stage of stock regeneration [1]. The fundamental difficulty at this point is striking a balance between modernity and conventional urban patterns [2], and historic preservation is becoming a common element of urban planning and is seen as one of the major forces for revival [3]. Many scholars have studied urban change from the perspective of urban morphology [4–7], which emerged in the early 19th century, and three main schools of thought were formed: the Cozen historical–geographical school [4], the Muratori– Caniggia typological school [8], and the Versailles historic school [9]. All three viewpoints are based on old maps and materials, emphasizing the logic of urban composition [10], and advocate a historic evolutionary perspective to understand the city [11], despite the differences in their approaches. The Historic Urban Landscape (HUL) perspective and approach were verified to be an optimum ideology [12], which sees the city as the product of the interaction between the natural environment and human traditions accumulated over time [13], helping protect heritage areas in more sustainable ways [14]. On a theoretical level, two theories can serve as a guide for urban regeneration activity and sustainable development [15].

**Citation:** Shen, D.; Dong, S. Transition of Urban Morphology in the Mountainous Areas Since Early-Modern Times from the Perspective of Urban Historic Landscape—A GIS Tools and Historical Map Translation Approach. *Sustainability* **2022**, *14*, 12896. https://doi.org/10.3390/ su141912896

Academic Editors: Lucia Della Spina, Paola Pellegrini, Antonia Russo, Maria Rosa Valluzzi and Angela Viglianisi

Received: 3 September 2022 Accepted: 26 September 2022 Published: 10 October 2022

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The historical process of urban modernization in China started around the late Qing Dynasty (the late 20th century) and is characterized as complex, dynamic, and nonuniform [16]. Sorting out the process is especially crucial during the period of urban regeneration [1]. Most of the materials that exist to record urban changes are historical documents and maps, which are essential to the historical study and reconstruction of the rural landscape [17]. Urban development now requires the use of cutting-edge research, technology, and tools to combine the database of historical urban geographic information [18].

The mountainous environment is widely spread in the world, where twenty-six percent of the world's population lives and covers twenty-five percent of the global land area [19]. Mountainous cities with undulating topography and complicated road networks offer an urban environment distinct from that of plain places [20]. There is some research on mountain cities that addresses spatial morphology and historical development, with the majority concentrating on ecology [21,22], geography [23], transportation [24], etc.

Chongqing, in southwest China, is a typical mountain city and has developed into a crucial hub city due to its advantageous position. Situated at the confluence of the Yangtze and Jialing rivers, Chongqing City has been an important town in eastern Sichuan since ancient times [25]. Most studies on Chongqing's cities concentrate on the macro and regional levels [26] and the technical elements of environmental ecology [27], with little research looking at meso and micro spatial patterns. Taking Chongqing as a study case can contribute to spatial morphology evolution research and the study of mountain cities.

This study aims to provide a historical-level theoretical foundation and research methodology for the universal city during the stock regeneration stage. With this aim, this paper creates an integrated city history map as a basis for historical research, and the city history map contains information over time, from the late 19 century to now, based on historical maps and documents [28]. Then, this paper establishes a set of urban historical transformation research approaches and frameworks from the perspective of HUL and urban morphology, using historical materials as research materials and cuttingedge technology to examine how urban morphology has changed through the case study of Chongqing.

Additionally, the majority of studies on this topic focus on the modern era (the late 20th century–1948). During this period, China has undergone a huge modern transformation. Modernization is complex, dynamic, and non-uniform and a hot topic in Sinology [16], so a large number of scholars have studied this period, and few focus on the post-statehood era (1949–2022). However, the time frame of this paper is from early-modern times to the present, bridging the gap in the study of Chongqing's urban morphology changes since 1949 in terms of time scale.

#### **2. Materials and Methods**
