目前台灣地區之基本圖,是以二度分帶橫麥卡脫(TM)為其地圖投影模式。本文旨在說明二度分帶TM與地理座標系經緯度間之相互轉換,並探討座標轉換過程的可逆性。從而瞭解計算過程中,有效位數、捨位誤差等因子之影響程度。
Transverse Mercator map projection is the official projection used in Taiwan area for mapping purposes. Two degree zoning with central meridian on 121° East is selected for the 1/5,000 base map. This paper discusses the coordinate transformation procedure between 2° Transverse Mercator (E, N), and the geographic coodinates (φ, λ). The reversibility of the coordinate transformation is studied to understand the extent of influence from significant digits.