IMAGE-BASED MEASUREMENT OF THE MING GREAT WALL 
Chen Jun, Zhao Yousong, Liao Anping, Jing Shuping, Zhang Hongwei 
National Geomatics Center of China Tel: +00861068424072 - chenjun@nsdi.gov.cn 
Commission V, SS/9 
KEY WORDS: Photogrammetry, Image Interpretation, Great Wall, Cultural Heritage 
ABSTRACT: 
The Great Wall is an ancient Chinese fortification against the raids of nomadic tribes and is the longest human building in the world, 
built over 2000 years and 10 dynasties in the Chinese history, and stretching over more than 10,000 km. It was made a UNESCO 
World Heritage Site in 1987. There are no precise and full recordings about the Great Wall, resulting in the difficulty of preservation, 
research, exploration and management of the Great Wall. It has important practical significance on how to measure scientifically the 
length of the longest human building in the world and issue the important geographic information related to the Great Wall such as 
the length, distribution, etc. The paper presents the method of measuring the Ming Great Wall based on image with the technology 
support of the field investigation and photogrammetry. The key technology of the method is to interpret and identify the Great Wall 
based on ortho-image dababase, testify the attribute and distribution by the field investigation, measure the surface length by the 
photogrammetry. The test result shows that the measuring accuracy of the surface length of the Ming Great Wall (5000km) will be 
0.866km based on the method. The method has been used by the 10 provincial bureau of surveying and mapping along the Ming 
Great Wall. 
1. INTRODUCTION 
The Ming Great Wall (MGW) was built from the end of the 
14th century until the beginning of the 17th century during the 
Ming Dynasty, with longer lasting materials (solid stone used 
for the sides and the top of the Wall). It stretches over more than 
6000 km, from Shanhai Pass on the Bohai Gulf in the east, at 
the limit between China proper and Manchuria, to Lop Nur in 
the southeastern portion of Xinjiang Uygur. 
Important geographic information relating the MGW such as the 
position, the distribution, length, attributes etc., is prerequisite 
to help the government to make the protect plan and carry out 
the protection of the MGW. However, there are no precise and 
full recording about the whole MGW up to now, resulting in the 
difficulty of preservation, research, exploration and 
management of the MGW. 
In 1985, the Remote Sensing Center of the Geology and 
Mineral Resources investigated the resources of the MGW in 
Beijing using ways combined the interpretation of the aerial 
photo and field investigation, measured the projection length of 
the section of MGW through the 1:50k topographic map in 
Beijing (Guwei,1985) . In 1990, the same way applied to 
Ningxia’s part of the Great Wall, northwest of china. But the 
projection length and the paper investigation results can not 
fully meet the need of the current cultural heritage protection, 
preservation, research, exploration and management. 
Hadrian’s Wall built in AD 122 and was to cross the narrowest 
part of England, from the Tyne to the Solway, and served as the 
frontier for almost 300 years. The great British Ordnance survey 
made 1:10,000 scale DLG of Hadrian’s Wall and measured the 
length (the total length is 117 km) with the help of the cultural 
heritage organization. At the same time, the close contour 
survey of the important forts has been done by the TC403 total 
station. The Close contour survey provides an accurate 
representation of both the surface terrain model and an accurate 
record of elevation ( J A Biggins,2000). The successful 
experience of Hadrian’s Wall measurement is the cooperating 
between the surveying and mapping unit and the cultural 
heritage organization. 
In order to complete successfully the resources investigation 
and measurement of the MGW, the State Bureau of Surveying 
and Mapping (SBSM) jointly with the State Bureau of Cultural 
Heritage (SBCH) decided to implement the task together. 
SBCH is in charge to investigate the attribute of the MGW, 
such as the building age, building materials, destroy status etc. 
SBSM takes charge of measuring the length of the MGW, 
capturing the base and thematic data of the MGW. 
Three majors tasks need to be carried out by both SBSM and 
SBCH: mapping the spatial distribution of the MGW and 
deriving relevant statistics (such as length), investigating and 
recording the attributes and status of the entities and auxiliaries 
of the great wall, setting up the great wall geo-spatial 
information systems. 
The paper will mainly introduce the method of image-based 
measurement of the MGW. The characteristic of the method is 
that utilizing the image to distinguish the distribution of the 
MGW and investigate in the field, expressing the attributes of 
the MGW on the image, capturing the MGW foundation 
geographical and thematic data using image, measuring the 
length of the MGW based on the image etc. 
2. METHODOLODY 
There are some difficulties for measuring the length of the 
MGW. First of all, it is difficult to locate the MGW and decide 
the attribute without cultural heritage expert’s knowledge such 
as building up age, classes of the wall due to the lacking of 
precise recording both in map and literature. Secondly, the 
MGW was built on different topography and the structure of the 
MGW is complicated. It is difficult to measure and map the 
MGW in the places such as the steep mountainous place wall,