The oil and gas industry requires both geological maps (as part of a suite of information) to locate sites for drilling and also topographic maps and cartographicfland cover maps for logistics planning when establishing drilling sites. Images recorded over ocean areas are being used to identify natural oil slicks which aids in the location of off-shore oil deposits. Interferometry-based monitoring of land subsidence caused by gas and oil extraction has become a new important application. Geological mapping with SAR data has become well established and a number of organisations offer a commercial service for mapping structure but the effect of layover in hilly terrain prevents widespread use of the data.