*2.1. Historical Urban Landscape Perspective and Research Framework*

A city's internal growth of its physical shape is the result of social, cultural, and other factors operating together, according to urban morphology, which emphasizes that the city is a combination of natural geography and artificial environment and that its development is a dynamic and continuous process [29–31]. Based on this, the intangible aspects of the urban landscape (which includes the natural and cultural as well as the physical and intangible) are given special consideration in the field of the urban historical landscape. Therefore, learning about the city from the perspective of the historic urban landscape is an essential first step.

The creation of a general- suitable framework (Figure 1) for the investigation of historic urban landscapes is attempted. Each urban component is interdependent on the others; thus, it is important to include the macro-regional, meso-city, and micro-block levels as part of the study context, and the linked contextual combination is the basis for conducting the study. It is, on the one hand, the physical of the city. Conzen's framework of townscape study begins with three aspects—pattern of plan, land use, and building forms—but the plan pattern is the most conservative morphological complex since it has remained relatively unchanged throughout the city's history. In order to study and explain the formation process of the plan pattern, a historical evolutionary perspective is used, and the elements of the plan are broken down into street and street-system, plots and street-block, and block-plan [29]. Street is the skeleton of the plan, its geometry and topological structure are the elements studied, and the street lines divide the street-blocks, each containing a series of property plots, the shape, and organization of which reflect the geographical variation. Block-plan refers to the area occupied by the building, and its shape and relationship to the plot are elements of the study (Figure 1). On the other hand, the perceptible space of the city highlights the subjective cognitive and perceptual side and can be studied through literature, images, and research materials from various time periods in order to analyze the public perception and supplement the daily life and invisible side of the city from an empirical vantage point [32,33].

**Figure 1.** A general-suitable framework for the investigation. (Source: own study).

### *2.2. Historical Map Translation Method and Integrated City History Maps*

For studies of urban evolution, particularly the city plan portion in the framework above, historical maps are a crucial source of information. City plans are a picture of the historical landscape's layers and are a goldmine of historical data.

This investigation spans the period between the late Qing Dynasty (the late 20th century) and the current day, and it includes maps of cities created before the formation of the People's Republic of China. Inaccuracies in cross-temporal spatial comparisons are inevitable due to the fact that the available historical maps were mostly created in a measured way, creating a gap between the precision of geographical position and the accuracy of contemporary maps. In order to visually portray the information of the current city on modern maps [28], it is important to utilize the historical map translation technique to convert the early historical maps into integrated history maps of the city using modern maps as the map foundation.

The four processes that make up the historical map translation method are the basic divisions. The selection of historical maps is the first stage. These historical maps may be categorized into three groups based on their use: mapping maps, thematic maps, and planning maps. Table 1 displays the ten typical maps that have been chosen. Most of the time, the other two types of maps are used as supplementary reference materials, but mapping maps, which contain rich geographical elements such as topography, water systems, and man-made features such as buildings and roads, are the most important materials for historical map translation work [34,35].


**Table 1.** Modern Historical Mapping, Thematic Maps and Planning Maps of Chongqing (Source: Historic maps, The historical atlas of Chongqing).

The second step is extracting, filtering, and classifying map information's constituent parts. The informational components on the historical map must first be removed. Because of the urban morphology and traffic network involved in this research, the retrieved components must be inspected and categorized. However, certain thematic maps may also give information on population distribution and land use, and it excels at obtaining aspects of quantitative categories such as perimeter and side lengths.

The third step is using Arcgis to align, locate, and overlay the fixed components as the reference coordinate system. The study components are placed and overlaid on the maps using the fixed elements as spatial reference coordinates, and the historical maps are aligned with the contemporary satellite maps using Arcgis. A basic direction in terms of area, time, and information should be present throughout the translation process. Translating the main streets, waterways, and other elements based on the city gates and walls is a good example of setting the big spatial pattern before refining others; translating maps not drawn with modern technology is a good example of restoring maps closer to the present time first [28].

Using the 1940s Yuzhong District map as an example, fixed elements were identified from a modern satellite map and used as control points; existing city gates and landmarks were then used as precise reference coordinates; these eight coordinates (Table 2) were comprised of the locations of the four city gates (Dongshui, Taiping, Renhe, and Tongyuan) and four landmarks (Jiaochangkou, Monument to the people's Liberation Xiaoshizi, and Bashu Secondary School). The current satellite image of Chongqing City from Google Earth and the 1946 Chongqing City Street Map were imported into Arcgis. Using the "Geographic Alignment" toolbar and the current satellite map as the base map, the eight control points on the 1946 Chongqing City Street Map and the current satellite map were clicked one by one until they were aligned. The information on the same historical stage is then translated into this map (Figure 2).


**Table 2.** Eight precise reference coordinates (Source: Google Earth).

**Figure 2.** (**a**) Reference coordinate in Google Earth satellite map; (**b**) Geographic alignment in Arcgis; (**c**)Translated map-Transportation situation in the 1940s; (**d**)Translated map-Important buildings distribution situation in the 1940s. (Source: Arcgis Screenshot, historical maps).

In the final step, errors are corrected using documentary sources. There is a need for further geographical correction of the spatial information retrieved from the historical map, and this correction is mostly based on textual information [28]; the majority of this textual information is sourced from local records and other authentic historical sources. It takes time to translate historical maps, and the newly created urban historical maps must be continually improved.
