Abstract:

Four classical edge enhancing methods in gravity and magnetic exploration field are compared: Tilt derivative, horizontal gradient of Tilt derivative, Theta angle and normalized standard deviations. All of them can amplify high frequency anomalies related to edges. An  approximate edge detector can be used in enhanced contour maps where local maximum relates to geology edge. While Canny edge detector can deal with enhanced map where inflexions relate to geology edge. Module tests in theory show that, comparing Canny edge detector for Tilt gradient map with approximating edge detector for other edge enhance map, the edge positions detected with the former accord with the real positions more accurately and there are fewer fake edges. In the applications, use is made of this method to deal with the local gravity of Meishan iron ore and to help approximately locate the boundary of iron bodies.

Key words: edge enhancement, edge detection, Tilt derivate, Canny operator, gravity anomaly