Edge detection in potential fields with the normalized total horizontal derivative

Edge detection plays an important role in the interpretation of potential field data. There are many methods based on horizontal and vertical derivatives to delineate the edges of sources. A universal disadvantage of these methods is that they cannot display the large and small amplitude edges simultaneously. In order to solve this problem, a new edge-detection filter is presented (the normalized total horizontal derivative (NTHD) method). The NTHD method is based on the ratio of the horizontal derivative to the maxima of nearby values. The NTHD filter is demonstrated on gravity data and magnetic data from China. The resolving power of the NTHD method is evaluated by comparing the results with those obtained by other similar edge-detection filters based on the horizontal and vertical derivatives. The advantage of the NTHD method in the recognition of source edges is due to the fact that it can make the strong and weak amplitude edges visible simultaneously, and can bring out more details.