Integrating global positioning systems with satellite remote sensing: avoiding major pitfalls

Global positioning systems (GPS) have high potential for use with satellite remote sensing. However, there are a number of factors that may limit the suitability of GPS data for remote sensing purposes. Consideration must be given to hardware limitations, site characteristics, GPS operation parameters, satellite sensors used, and the user´s needs. Hardware considerations include power requirements, equipment specifications, the need for shelter, safety concerns, and various accessories that may be required. Site considerations are also important. It may be difficult to find or access a benchmark; trees and other tall objects will affect the quality of the GPS signals; equipment located at the site may be susceptible to damage or theft, and weather conditions such as snow or lightening may prevent or impede the acquisition of data. Major factors affecting GPS data include selective availability (SA), position dilution of precision (PDOP), signal to noise ratio (S/N), differential correction, accuracy of benchmarks, map accuracy standards, and techniques used in collecting the data. Satellite sensors determine the spatial resolution of the acquired image and this in turn defines the minimum acceptable accuracy of the GPS system. User´s needs define data requirements, and usually require conversions between geodetic datums, and map projections. Successful integration of these two technologies requires careful planning and attention to detail. It can result in better ground truth, faster acquisition of field data, and an improved final product. The authors have attempted to cover areas that can be major hurdles to the use of GPS in satellite remote sensing. It is based on the authors´ use of GPS data with Landsat and ERS-I images