ROBUST EXTRACTION OF ANCIENT BURIAL MOUNDS IN BRUSHLAND FROM LASER SCANNING DATA

摘要

Moroyama town, where is located in the southwestern part of Saitama Prefecture is a historical town including more than 80 ancient burial mounds. These ancient burial mounds locate in brushland. The diameters of these ancient burial mounds are about 5-15m, but there are small mounds less than 5m diameter which shows only top part of the mounds, bigger mounds more than 20m diameter and keyhole-shaped mounds. Therefore, it is supposed that some of the small ancient burial mounds are not yet found because the ancient burial mounds are covered with trees. The authors have been concentrating on developing an efficient extraction method for ancient burial mounds which are covered with trees using laser scanning data. However, filtering method and threshold values for robust extraction of the mounds from smaller to bigger are issues. With this motive, filtering and thresholding approach for an efficient extraction from smaller to bigger mounds using pyramid filters are proposed in this paper. The most remarkable points of this approach are its ability to extract from smaller and bigger mounds efficiently. In particular, the proposed pyramid filtering show the ability to extract smaller mounds less than 5m diameter, and 11 mounds are newly extracted by the method. Furthermore, in order to perform visual investigation, landscape animation for the mound area is generated in this paper.