數值高程模型之品質評估

Quality Assessment for Digital Elevation Models

楊善智(Shan-Zhi Yang) ； 曾義星(Yi-Hsing Tseng)

《航測及遙測學刊》 13卷3期 (2008/09) Pp. 195-206

https://doi.org/10.6574/JPRS.2008.13(3).4

摘要

數值高程模型(Digital Elevation Model, DEM)乃廣泛被使用的空間資料，產製方法相當多元，不同時期不同方法產製的DEM品質不一，如何評估其品質是DEM使用者常面臨的問題。本研究針對不同時期及不同觀測方法所得之DEM，估計其內部和相對的外部精度品質。內部精度評估以最小二乘估計法爲本，但改善其搜尋計算點方式使其適合於取樣點分佈不均勻的情形。並提出一套相對外部精度評估方法及流程，透過高程比對分類，探討誤差的類型及可能形成的原因。所發展的理論及方法可用來評估單一DEM本身觀測結果之品質，亦有助於分析同區不同來源DEM間之相對精度品質。實驗資料包含以空載光達、航測及干涉雷達所生產的DEM，分別測試內部精度評估及相對的外部精度評估。內部精度評估成果分析合理呈現DEM因觀測取樣及地形因素影響之內部精度品質，透過DEM相互比對分析之相對的外部精度評估成果也能反應相對誤差的模式，得知是否含有平面或高程系統誤差，也能呈現局部之區域性粗差。

關鍵字

數值高程模型 ； DTM ； DEM ； 精度評估 ； 品質評估

並列摘要

Digital Elevation Models (DEMs) are widely used in many spatial information related applications. There are a variety of technologies developed for DEM generation, such as digital photogrammetry, airborne LiDAR and InSAR. However, the procedure from raw data sources to DEM products may involve different types of errors, which determine the DEM quality. Therefore, methods for DEM quality assessment are needed for users. This study proposed two methods to describe DEM quality-interior and exterior relative quality assessment. Instead of whole index of RMSE, the former provides accuracy index of each height point calculated from the raw data to reveal the DEM quality in a local area. Then the later explores the relative errors between DEMs acquired from different sources and times. The two methods provide useful information to DEM quality assessment, which makes a user to realize the quality of acquired DEMs in detail.

並列關鍵字

DEM ； DTM ； Quality assessment