基於電子海圖架構下之地理資訊系統天文定位

Using GIS to Obtain Celestial Fix under the Framework of an ECDIS System

鄒明城(Ming-Cheng Tsou)

《航運季刊》 23卷3期 (2014/09) Pp. 109-123

摘要

本研究提出一個在電子海圖（ECDIS）架構下以地理資訊系統（GIS）功能為基礎的簡單天文定位方法，是用以解決天文定位問題的新思考方向，其原理是回歸到天文航海最基本的定位理論，以天體的位置圈（COP）進行作圖定位，藉由GIS對於地圖資料的測繪、處理與分析能力，直觀的以作圖的方式獲取天文定位。從使用者的觀點來看，解除在紙海圖上進行海圖作業定位時所受到的限制，也避免了傳統截距法的繁瑣與不精確，以及數值解析方法的複雜計算與難懂原理。這樣的定位操作方式既簡單、易明瞭且精確，可適用於雙天體、多天體以及高高度觀測等各種定位條件，可作為發展ECDIS天文定位模組的參考，進而提供大洋航行時衛星定位的檢核與備援，此外，亦可作為現代天文航海教學在e化上的參考。

關鍵字

電子海圖架構 ； 天文航海 ； 地理資訊系統 ； 截距法

並列摘要

This study proposes a simple method for obtaining a celestial fix using a geographic information system (GIS) under the framework of an electronic chart display & information system (ECDIS). The underlying principle is dependent on the most fundamental theory in celestial navigation and the circle of position (COP) of the celestial bodies is plotted to find the fix. Through the spatial data processing, analysis, and visualization capabilities available in GIS, a celestial fix may be obtained directly from plotting on electronic navigation charts. This eliminates the limitations associated with finding the fix manually using a paper nautical chart, but also avoids the cumbersome work and inaccuracy of traditional intercept method (IM), or the complicated, and often obscured, computation involved in numerical methods. The proposed method is simple and accurate, and it applies to situations involving two or more celestial bodies and high-altitude observations. It provides a reference for the development of a celestial positioning module in an ECDIS system, as a backup and position check means for global positioning system (GPS) while ocean passage, and could also be integrated into an educational program on electronic celestial navigation.

並列關鍵字

Electronic chart display & information system (ECDIS) ； Celestial navigation ； Geographical information system ； Intercept method