A Holistic Study and Digital Practice of the Great Wall(Part 2)

2.Digital Practice

The vast system of the Ming Great Wall presents challenges for holistic conservation and holistic digital reproduction. The Great Wall protection in China began after the founding of the People's Republic of China, and under the initiative of "Love China, Repair the Great Wall", repair projects such as Shanhaiguan and Jiayuguan were carried out, and three cultural relic censuses and Great Wall resource surveys left precious actual measurement data for the authentic appearance of the Great Wall heritage, and the general work plan of the Great Wall protection project was formulated at the end of 2005, and the Great Wall resource survey was completed from 2006 to 2011. In July 2019, the General Office of the CPC Central Committee and the General Office of the State Council issued the " a plan on the construction of national culture parks for the Great Wall, the Beijing-Hangzhou Grand Canal and the Long March", which specifies six key tasks and five types of key projects （protection and inheritance project, research and excavation project, environmental support project, cultural and tourism integration project and digital reproduction project）。

The digital reproduction project group has made progress in historical excavation, information collection, database construction, digital cloud platform construction and museum display, providing support for the establishment of a core data resource platform, integrated management, release and sharing of scattered Great Wall data resources.

2.1 Database construction for the whole area and line of the Ming Great Wall

In view of the complexity of the Ming Great Wall system, the group built the "Spatio-temporal Database of the Ming Great Wall Defense System" to visualize the whole area of the Ming Great Wall defense system, including the spatial distribution and attribute information of more than 1,000 cities, 1,000 passes, 2,000 post passes and 2,000 beacons.

In order to understand the location of the Great Wall, construction practices, building materials, remains and damage, the group has taken 2 million photos through more than two years of field aerial survey, built "the whole line of the Ming Great Wall image and three-dimensional database" and its building target intelligent recognition model, completed 5500km close photogrammetry of the Ming Great Wall （the total length of the artificial wall is 6200km）， and can generate continuous three-dimensional data of the wall.

The system supports the viewing of historical information and current photos of each subsystem, and also provides panoramic roaming and family restoration model to show the whole picture, so as to break the misconception that "the Great Wall is a linear wall". The system also enables the display of the Great Wall's most （most in scale and specification, most in construction and quantity, and most in distribution and preservation）。 It also supports wall damage monitoring along the entire length of the Ming Great Wall, showing the damage of the same section before and after 10 years （images and quantitative analysis）， and providing post-data updates and IOT services （Figure 6）。

Figure 6: Spatial-temporal database of the Ming Great Wall defense system, image and 3D database of the entire Ming Great Wall

2.2 Online cloud platform development

The scale of the Great Wall is so huge that digital reproduction/twinning is the best means of display and one of the fifth major projects of the national cultural park. The group proposes to build a digital management system （cloud platform） for the entire line heritage, merging the five major projects of the Great Wall National Cultural Park construction into one, making the online and offline travel integration projects closely linked, and realizing synchronized, real-time and complementary online virtual tours of the large-scale line heritage and the park system. The platform is geared towards audiences with different needs at domestic and international levels, and is in a position to open up digital resources and professional databases to achieve global and extensive dissemination of cultural values. The Great Wall digital cloud platform builds 3 levels of content for research institutions, management agencies and public groups respectively: （1） the Great Wall basic information data layer, （2） the Great Wall cultural knowledge application layer, and （3） the public display tour service layer （Table 1）。

The "Cloud Tour of the Great Wall" platform and WeChat mini-program jointly built by the research group and Internet enterprises will be launched soon, which is composed of four modules: Ming Great Wall defense system, knowledge topics, research documents, and high-definition photos. The whole platform covers the following contents: distribution of the continuous wall of the Ming Great Wall, pictures of the current status of the wall, 3D images and panoramic roaming of the wall, composition of the Great Wall defense system, distribution of towns, knowledge of the Great Wall, architectural features of the wall at all levels, explanation of the terms of the Great Wall defense system, introduction of the Great Wall architectural types, etc. For the first time, the full view of the Ming Great Wall defense system is shown to the public （Figure 7）。

Figure 7: The background interface of the "Great Wall in the Cloud" and the Great Wall Cultural Resource Library （coming soon）

2.3 Museum construction supported by big data

Museum construction is an important element in the construction of the Great Wall National Cultural Park. In the exhibition outline preparation and content design of the Shanhaiguan China Great Wall Culture Museum （tentative name）， the group visualized the systematic relationship of the Great Wall defense system, and the permanent exhibition hall was divided into five parts: construction and development of the Great Wall, Great Wall military and defense, Great Wall construction and architecture, Great Wall garrison life, and Great Wall border trade and culture.

The section on the occurrence and development of the Great Wall will use data on the Great Wall system in the Han, Tang, Jin, and Ming dynasties to display continuous aerial images and three-dimensional digital images of the Ming Great Wall without blind spots, and for the first time, to "fly" freely over the entire length of the Ming Great Wall, realizing a dynamic demonstration of the wall distribution in space and time over the generations; The Great Wall construction and architecture section will use data on the spatial relationship between the Han and Ming military systems and the defense system to change the traditional perception that the Great Wall is just a wall, and to establish an aerial tour route between each pass, fortress and beacon to show the complete Han and Ming defense system; the Great Wall construction and architecture, and the Great Wall garrison life sections will use 3D point cloud models to extract many of the "Best of the Great Wall" from a full perspective, including scale and specifications, structure and quantity, distribution and preservation; The Great Wall Border Trade and Culture section will use the spatial distribution of the existing Ming Dynasty trade markets, aerial photographs and historical materials to excavate the process of trade exchange, show the historical norm of north-south, east-west exchanges and integration inside and outside the Great Wall, and explain that "the Great Wall is not a confrontation" （Figure 8）。

Figure 8: The background interface of the "Great Wall in the Cloud" and the Great Wall Cultural Resource Library （coming soon）

3 Conclusion

Through the construction of the basic database, the construction of the digital cloud platform shared by the public, the digital display of the museum and its IOT construction, the authenticity and integrity of the Great Wall is demonstrated to the international and domestic society, which is an effective way for the holistic conservation and sustainable development of the Great Wall. The survey of Great Wall resources shows that only 8.2% of the 6259.6km-long artificial wall of the Ming Great Wall （not counting the length of trenches and natural hazards of about 2500km） is still in good condition, while 74.1% is poorly preserved or only the basal part remains. This is true for walls, but even more so for beacons. Based on the holistic study, the group will comprehensively collect information on the current status of the remains in order to complete the construction of comprehensive digital reproduction, which may promote the holistic conservation and sustainable development of the Great Wall's large-scale heritage through the spatial relationship of the transmission routes of the post and beacon system, the virtual recreation of the vanished and dying sections, and the response relationship among the heritage sites.

Source:< <https://mp.weixin.qq.com/s/NKKy0VIFoT-_WtXy9zxCZg》

Translated by Hou Ying