抄録
The influence of radar look-direction on the detectability of lineaments is investigated using low depression angle SAR images of Japan. Regardless of various trends of general geologic structure in interpreted areas, the results of lineament interpretation show selective enhancement of lineaments with strikes at 20-30 degrees to the look-directions. To explain this tendency, a topographic model is proposed, which is modified from the model of Wise(1969) to fit dissected topographic relief in mature stage of Japan. That is, the author took into account of the influence of radar shadow formed by 1st order valleys develop in smooth slope of the Wise' s model. Based upon this modified model, the geometrical relationship among look-direction, depression angle and the angle of 1st order valley slopes provides the conditions for maximum shadow enhancement, and relative frequency of the valleys which satisfy these conditions becomes maximum when the strikes of the valleys are 20-30 degrees to the look-directions.
