Recognition and extraction of the ancient sites covered by thick vegetation in Hainan Province of China

The 3^rd National Cultural Relics General Survey in Hainan Province was started in early 2008. As the advanced technological method, remote sensing was introduced to support the survey because of the inaccessibility of tropical forests. We collected Landsat images, ALOS images and black-and-white aerial photos and corrected them all. Based on the common principle of remote sensing in archaeology, we analyzed two factors: sunshine and nutrient; then we got the special principle in tropical vegetation regions. In the end, we chose Qiongshanjiuzhou, Zhuyaling, Dayapo and Nanjianzhou Ancient City as typical examples to demonstrate the important roles remote sensing played in recognizing the border of ancient city sites and calculated the perimeter and area of each ancient city site.