Edge detection of gravity anomaly sources via the tilt angle, total horizontal derivative, total horizontal derivative of the tilt angle and new normalized total horizontal derivative

In this paper the application of edge detection techniques to gravity data are described. Edge enhancement in potential-field data helps geologic interpretation. There exist several methods for enhancing edges, such as tilt angle, and the derivative of tilt angle. Most of these methods are high-pass filters based on the horizontal or vertical derivatives of the field. To determine the filters new normalized total horizontal derivative (NNTHD), normalized horizontal derivative (NTHD), total horizontal derivative (TDX) and tilt angle as an edge detector (THDR), a computer code in Matlab was prepared. The filter has been tested by comparison with related high-pass filters with synthetic data and measured data; it gives outstanding results for the data sets employed for which the NNTHD method can make large and small amplitudes of source edges equally visible, with more detail wherever the data are relatively smooth. NNTHD, a new edge-detection filter, is based on ratios of horizontal derivative to the mean of the nearby horizontal derivatives. Compared with other filters, the NNTHD filter produces more detailed results. The advantage of the NNTHD 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. The advantage of the NNTHD method is most obvious in the regions where the data are relatively smooth. As the standard deviation of this method (0.1784) is greater than the NTHD method (0.0710), this method displays the gravity anomalies more clearly than the NTHD.