Examining alternative methods for zone based UTM system

SUMMARY Examining Alternative Methods for Zone Based UTM System Recently, as a result of growing GPS and Remote Sensing techniques, the studies exceeding a UTM zone are increasing in regional and national GIS studies and engineering projects covering wide areas. In such applications, users prefer a common coordinate system for the project area. When a project area is not in a common coordinate system, it is required that the project is stored in different files. This leads to some disorders overlapping regions of the project. UTM system used as a map base in Turkey is also based on zone principle. So, there are four coordinate zones in UTM system and seven coordinate zones in modified UTM system. With respect to the provision of a common coordinate system, UTM system is not adequate for the countries like Turkey extending east-west direction. In this study, three alternative mapping methods were evaluated instead of UTM system. The first is the TUTM system developed for geographical borders of Turkey by extending zone-width of Gauss-Kriiger mapping. The second is double conformal mapping from ellipsoid to sphere and then from sphere to plane. The last is Lambert Conformal Conic (LCC) mapping with single and double parallels. Calculations of projection equations of alternative methods from geographical coordinates and inverse solution equations were also evaluated in detail. In addition, the different direction and distance reduction formulas developed for each method were provided. The alternative methods for geographical borders of Turkey were compared using the distances and azimuths determined in different regions and lengths. While plane azimuths and distances were calculated with mapping equations, ellipsoidal azimuth and distances were calculated via the geodetic problems. Ellipsoid and plane differences were calculated at different coordinate zones for each method. Thus, the most convenient coordinate zones were selected for these methods. Then, the reduction formulas for each method also compared with differences of ellipsoidal-plane direction and distance, and the most sensitive of them was identified. As a result of evaluations, it is concluded that while TUTM system is convenient for engineering projects, double standard parallel LCC mapping is convenient for GIS applications in which high accuracy is not important. Key Words: UTM, GPS, GIS, Remote Sensing, TUTM, Conform Double Mapping, Lambert Conformal Conic, Direction and distance reduction VI