Extraction of Magnetic Local Anomalies Based on GIS

With the rapid development of geophysical surveying in China, the geophysical data is increasing quickly. However, it is still a challenge of how to improve the efficiency of data processing and interpretation. Most of the local anomalies are shown as local protuberances on profiles which are similar with hills in the digital elevation model (DEM). Based on ridge lines and the local greatest gradient, an algorithm of local anomalies extraction is proposed in this paper: taking the ridge point as the center, searching outward to the greatest gradient, filling the interior of anomaly areas, and finally finishing the extraction of local anomalies. Simultaneously, local anomalies of interest are obtained by retrieval of three parameters (axial orientation, intensity and average slope). Proved by the instance on the spot, local anomalies extracted by this algorithm are corresponding to manually selected anomaly points, which can greatly reduce the searching area and improve efficiency.