Precisely how long is the Great Wall of China? Because historical records and measurements differ, officials in China have decided to survey the length and orientation of the Great Wall, using the latest techniques and a budget of 200 million yuan (approximately US$ 25 million).
Hong Kong's Mingpao Newspaper reports that The Information Center for Basic Geography of China's State Bureau of Surveying and Mapping will use state-of-the art techniques such as aerial mapping via remote sensing, GIS (Geographic Information Systems), and GPS (Global Positioning System) to measure the exact length and orientation of the Great Wall, built in the Ming Dynasty (1368-1644 CE).
Mr. Zhang Ji, vice secretary-general of the Great Wall Association of China, said that when the measurements are completed, a 3-D image of the Wall will be posted on the Internet.
According to the Hong Kong newspaper, there are still no definitive data on the Great Wall's exact length. The present figure of 6300 kilometers (approx. 3800 miles) provided by the Great Wall Association is based on documents from the Ming Dynasty. During the post-1949 Communist era, local governments have undertaken their own surveys, but their findings, which reveal a length of over 7000 km (approx. 4500 miles), differ from the official one due to unclear regional boundaries, the paper reported.
For the new survey, an airplane equipped with a remote sensing camera will take photos of the Wall while flying along it. Any damaged parts of the Wall will be located using archaeological analysis and the age of the soil.