Utilization of Structure from Motion for processing CORONA satellite images: Application to mapping and interpretation of archaeological features in Liangzhu Culture, China

Remote sensing has been supporting archaeology since the early 20th century. Recent high-resolution satellites have enabled the detailed observation and mapping over wide areas enhancing the importance of remote sensing techniques. Besides its severe geometric skewness, CORONA satellite image, the reconnaissance satellite of United States operated during the 1960 to 1972, has provided a wealth of historical information. From CORONA satellite images, archaeologists can begin to understand the original landscape of sites worldwide that have undergone rapid urban expansion. However, most previous archaeological studies of CORONA satellite images have focused on homogeneously textured arid condition with little vegetation. The present study maps and analyzes the Liangzhu sites group near Shanghai, China, which occupies a low wet environment in the temperate climatic zone. The CORONA satellite images were orthorectified by the Structure from Motion technique and subjected to digital surface model (DSM). The accuracy of the orthorectified image was confirmed by evaluating the root means square error. However, the extracted DSM suffered from speckled noise and the so-called bowl effect distortion. > 80% of the known sites were successfully detected through stereoscopic interpretation and additional unknown features were metrically mapped. The parallel dike-like features of the Tangshan complex were reconstructed and their likely function suggested.