福衛二號立體像對產製數值地表模型精度分析

Accuracy of the DSM Generation from FORMOSAT-2 Stereo Pairs

台灣地形起伏劇烈，加上地殼變動、氣候等各種自然營力作用下，使地形變化迅速，尤以山區為甚。福爾摩沙衛星二號可提供前後各45度角擺動，進行同天同軌立體對取像。本研究以福爾摩沙衛星二號台灣山區立體影像對建立5m數值地形模型（DSM），輔以DGPS與航測所得數值地表模型進行比較，除採一般常用RMSE（Root Mean Square Error）評估精度外，也利用LE（linear error）／CE（circular error）評估整體資料可用性。分析結果其高程誤差RMSE為4.19公尺，LE68標準下為±2.91公尺，LE95標準下為7公尺。福衛二號除對國內外重大自然環境災害後，能迅速提供受災區地表現況影像外，另可對大範圍地形變化偵測亦能有所助益。

With its unique design, FORMOSAT-2 satellite has the capacity to provide along tract stereo pairs at a daily revisiting frequency. These stereo pairs can be used to extract DSM that is important in terrain analysis, hazard assessment and monitoring. 4 meters resolution digital surface models (DSMs) was extracted from FORMOSAT-2 stereo pairs and compared with DGPS and DSM data which was generated from aerial photos to determine the accuracy. The RMSE between FORMOSAT-2 DSM and reference is 4.19m, with 68% (LE68) and 95% (LE95) confidence level at 2.91 meters and 7 meters respectively.