Extraction of craters as concentric circle patterns of contours on the lunar digital terrain model

Impact crater is one of the important topographic features on the planet. Size-frequency distributions of craters on the plan etary surfaces are used for determining planetary chronology. This paper presents an algorithm for automatic crater detec tion to reduce time to counting craters. A crater is a circu lar depression. So contour lines of a crater on a topographic model form a characteristic pattern of concentric circles. Our algorithm detects craters in digital terrain model (DTM) with this concept. There is no need to care the angle of the solar incident because the DTM is independent on the solar alti tude. An evaluation test with a lunar DTM shows that 80 % of craters more than 200 m in diameter are extracted. So there is possibility to extract most of craters, including small size of craters such as them, on the planet by more improvement of the algorithm. Most false detections are caused by unintended detections of circular positive reliefs, non-crater circular de pressions and other complex topographic features.