以TIN為基礎之數值地圖套疊法

A NUMERICAL METHOD OF MAPS OVERLAYING BASED ON TIN

將二張紙地圖套疊在一起使用，是許多地圖使用者經常會遇到的工作。然而，由於地圖套疊作業往往因為地圖座標系統不一致，或因為圖紙的伸縮，或因為圖形生產時使用不同的數化控制點或引用不同的測量控制點，因而導致地圖套疊作業不易或無法完全重疊。本研究嘗試建立一套地圖套疊的數值模式，以解決前述人工套疊地圖時所遭遇的困難。首先，先將紙地圖轉換成向量或影像的資料形式，然後再將向量資料形式的圖形資料分解成單一座標點資料及空間位相資料二部分。接著，再於二地圖上選取代表空間上相同位置的控制點組合，並藉由Delaunay法來建立TIN。之後，再將此二圖套疊並使用插補法來轉換其中一張地圖的座標值，以達到將二地圖完全套疊在控制點處的效果。研究結果顯示，以TIN為基礎的地圖套疊方法可以使二地圖完全套疊在控制點處。

Maps overlaying is one of the most commonly tasks for many maps users. However, in reality, due to the differences in coordinate systems of maps, the shrinking of paper maps, or the use of different control points when digitizing and surveying, the task of map overlaying is becoming very difficult, if not impossible. This research attempts to establish a numerical method of maps overlaying in order to overcome the disadvantages currently encounted in practice. First, paper maps are transformed into vector or raster form, than decomposited them into points and topology. Second, to chose a set of control points from these maps and use the Delaunay triangulation method to construct a TIN network. Then, to apply interpolation method to transform the coordinate values so that two maps may exactly overlaying at all control points. The final result shows that the overlaying method based on TIN can achieve a exactly overlaying of two maps at all control points.