Improved optical positioning for GPR-based structure mapping

Existing positioning technologies used in conjunction with Ground Penetrating Radar (GPR) are generally too time-consuming or insufficiently accurate for high resolution, high frequency, 3-d structural investigations. In this paper we present an optical positioning system for use in GPR surveys. This system uses a camera mounted on the GPR antenna that takes video of the surface beneath it and calculates the relative motion of the antenna based on the differences between successive frames of video. Positioning using this technology can provide positioning accuracy to within several millimeters. Because the antenna can be moved free hand the procedure is orders of magnitude faster than surveying a grid of data points or laying out parallel lines and surveying each line with an antenna and odometer wheel. Time domain synthetic aperture radar algorithms reconstruct an image of the subsurface using this data. This is a new technology, but one which has potential for future research, improvements, and practical use.