Evaluation and three-dimensional representation of ground-probing radar measurements

GPR measurements are made in both boreholes and drifts for exploration. Measurements with directional antennae not only allow the distance to the reflection points to be determined but also the angle with respect to the azimuth of the plane defined by the reflection point and the two antennae. If a directional antenna cannot be used, the location of the reflection surface can be determined by special placement of the antenna in a vertical plane perpendicular to the axis of the drift. The migration method we use makes it possible to determine the point of reflection from the traveltime and the angle defined above. A planar element perpendicular to the normal to the reflection surface can be assumed through each point of reflection. If these elements are connected with each other, a zone is obtained representing the location of the reflector. The calculation of the angle, the filter processes, signal attenuation compensation, and other kinds of data processing, including determination of the traveltime ("picking"), is done using an interactive computer program we have developed. A software interface has been developed to transfer the reflection points to a 3-D graphics system so that projections, cross sections, and spatial representations can be prepared.