Objective  Qingyi Garden, built in 1750 (renamed as the “Summer Palace” upon renovation in 1888), is a masterpiece of ancient Chinese royal gardens that represents the highest level of ancient Chinese garden design. Taking Qingyi Garden as an example, this research explores the overall design method of large royal gardens in Qing Dynasty, which is of great significance for expanding the design theory of Chinese classical garden and supporting the heritage protection of the Summer Palace.

Methods  The research first examines the basic nature of the map Qingyi Yuan Di Pan Hua Yang (a master plan of Qingyi Garden, hereinafter referred to as the “Map”) drawn by the royal design institution named “Yangshifang” in Qing Dynasty, and judges when the Map was probably drawn, how it was drawn, and the purpose of drawing it based on the morphology of the building groups therein and the actual construction time of these building groups. Meanwhile, the research quantifies and analyzes the overall layout of the building groups in the Map. Specifically, the research adopts the computer aided design (CAD) software to process the images and measure the axis spacing of the building groups, and then adopts the Microsoft Office Excel software to analyze the data to derive the cartographic features of the Map. In order to find the technical origin of these cartographic features, the research explores the relevance of these cartographic features to the Pingge technique prevailing in Qing Dynasty from three aspects: the modular features usually presented by the Pingge technique, the form and accuracy of topographic surveying and mapping in the Map, and the objective feasibility of using the Pingge technique at the beginning of the construction of Wanshou Mountain in Qing Dynasty. Based on the above research results, the research finally proposes the overall design method of Wanshou Mountain in Qingyi Garden, including core contents, key processes, technical features and historical value of the method.

Results  1) Based on the examination of the building groups in the Map (including Hanyuan Hall, Leanhe, Yunhui Pavilion, Yichun Hall, Gouxu Pavilion, etc.), it can be judged that the Map was probably drawn after 1840, but it only shows the general situation of Qingyi Garden for a certain period after 1840, rather than at any particular time. In addition, the orientation or scale of some of the building groups in the Map is different from the actual situation (such as Qiwang Pavilion, Kanyunqishi, Gaichun Garden, and Shanxian Temple), while other building groups are consistent with the actual situation. The above two points indicate that the Map was not drawn at a certain time through precise survey, but may be copied and redrawn from an early design plan of Qingyi Garden. It is believed that the Map, to some extent, reflects the early layout and design information about Qingyi Garden during Qianlong period in Qing Dynasty. 2) Quantitative analysis shows the existence of a consistent drawing scale and a drawing module of 5 zhang (roughly equal to 16 meters; “zhang” is a traditional Chinese length unit). 3) The quantitative features shown in the Map are closely related to the Pingge technique commonly used in large royal projects in Qing Dynasty, which can be proved by three pieces of evidence. Firstly, the drawing modulus “5 zhang” adopted by the Map is a common scale (commonly 5 or 10 zhang) used in the Pingge technique for large sites in Qing Dynast. Secondly, the topographic information in the Map is consistent with the actual topography of Wanshou Mountain. In Qing Dynasty, accurate topographic information about such a large mountain could only be obtained by surveying and mapping using the Pingge technique. Thirdly, according to historical documents, Wanshou Mountain had the objective conditions for topographic mapping of the whole mountain using the Pingge technique before the construction of Qingyi Garden. Therefore, the research concludes that the Map was drawn using a “5 zhang” Pingge map as the base map, and that the Pingge technique plays a key role in supporting the general layout design of Wanshou Mountain.

Conclusion  At the initial construction of Qingyi Garden in Qing Dynasty, the overall design (including the full range of the mountain) was carried out for Wanshou Mountain. The overall design method involves two key processes: surveying and mapping using the Pingge technique and overall layout based on appropriate Pingge map. The core of this method is to design on the basis of the Pingge map adopted (with accurate and quantified topographic information) rather than in combination with the real site in order to control the location, scale and axis position of the building groups as a whole. This overall design method satisfies the dual pursuits of order (on the whole) and appropriateness (in local environment) in classical Chinese garden design.