等距長方投影：古典地圖與現代360°影像

Equirectangular Projection：From the Classic Map to Modern 360° Image

「等距長方投影」，是一個使用歷史悠久的地圖投影，其優點為無論是由地理坐標化算為投影坐標，或是反投影，計算均為簡易。由於變形嚴重，並非現代地形圖之地圖投影中所常用，但是在主題圖製作中，仍屬常見。「等距長方投影」在現代的360°影像格式中，再度獲得應用。本文說明此一投影方式，並描述其特性，以為參考。同時，由所選擇之案例，探討其使用之機會。

Equirectangular projection is one method with a long history in cartography. The most outstanding advantage of this projection is the simplicity in both forward and backward computation. Due to its large distortions, equirectrangular projection is not commonly applied for topographic mapping, but frequently applied for thematic mapping. In modern 360° image and video file formats, equirectangular projection has been found in another application. This writing introduces this projection, describing its distortion along with sample applications.