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.

A human-robot interface system is under development that takes into account the flexibility of the DigitalDesk approach. The prototype consists of a projector subsystem for information display and a real-time tracking vision subsystem to recognize the human's action. Two levels of interaction using a virtual operational panel and interactive image panel have been developed. This paper presents the third subsystem, the interactive hand pointer used for selecting objects or positions in the environment via the operator's hand gestures. The system visually tracks the operator's pointing hand and projects a mark at the indicated position using an LCD projector. Since the mark can be observed directly in the real work space without monitor displays or HMDs, correction of the indicated position by moving the hand is very easy for the operator. The system enables projection of a mark not only at a target plane with a known height but also to a plane with an unknown height. Experimental results of a pick-and-place task demonstrate the usefulness of the proposed system.