Using Fish‐Eye Lens for GPS Site Reconnaissance

One of the problems in the use of Global Positioning System (GPS) is that of rapid site evaluation and point reconnaisance. The paper utilizes a system developed for solar easement site analysis by fish‐eye lens photography to allow rapid and accurate site evaluation by the Survey Engineer. This system allows prior analysis of satellite visibility windows, possible multipath problems and serves as a permanent site record. This analysis is accomplished by taking a vertical fish‐eye image and overlaying a computer‐produced satellite track in the form of an azimuth versus zenith angle plot. The result is an efficient determination of a site satellite window diagram giving an accurate and complete view of site conditions. This technique saves time over classic ground survey methods while producing reasonable accuracy and the fish‐eye image may be used to predict future problems with the site as vegetation sky cover changes with season and through time.