Optimal scale factor on the central meridian for a 2°TM map projection in TWD97

摘要

The purpose of this paper is to study the optimal scale factor on the central meridian in order to minimize distortions of the 2°Transverse Mercator map projection in TWD97. The optimal scale factor is first derived according to the Airy optimal theory of distortions. Next, the influences of the current and optimal scale factors on local length and area distortions are discussed and analyzed. The results show that the value of the optimal scale factor on the central meridian under consideration is 0.999942 and leads to minimal local distortions in both distances and areas on the island of Taiwan.