- 期刊
SPOT衛星稀疏取樣幾何於BRDF模式反演之精度評估
Accuracy Assessment of the Retrieval of BRDF Model from the Sparse Sampling Geometry of SPOT Satellite
摘要
本研究使用國立中央大學太空及遙測研究中心歷年來所收集之SPOT衛星影像太陽／觀測幾何資料集，評估SPOT稀疏取樣反演BRDF模式精度，精度之評估使用所反演之波段反射率之相對誤差。此研究重點在於BRDF模式反演之精度與稀疏取樣幾何和每月份影像個數之關係。研究結果指出，一般而言，反照率相對誤差隨月影像個數或該月觀測天頂角全距增加而減少，雖然相同之月影像個數下觀測天頂角之全距越小，相對誤差也未必越大。相近月觀測天頂角全距，相對誤差在可見光、近紅外光波段也可能變化超過45%和340%。此現象近紅外光波段與可見光相似。若某月影像個數大於6，且該月觀測天頂角全距超過17°，則所反演之可見光、近紅外光波段平均相對誤差僅達9.5%和43.5%。另外，近紅外光誤差較可見光大，乃因其大氣改正誤差絕對誤差較大之緣故。因此可預測在正規化多時多角度SPOT衛星影像時，近紅外光誤差會較可見光大。
並列摘要
In this paper, the SPOT dataset of solar/viewing geometry obtained from the Center for Space and Remote Sensing, National Central University are used to assess the accuracy of the retrieved BRDF from sparse sampling geometry of SPOT satellites. The relative error of the retrieved albedo is used to assess the accuracy. This study focuses on the relation of relative error of the retrieved albedo to both of sparse sampling geometry and monthly image number. The results show that in general, the relative error of retrieved albedo decreases as monthly image number or range of viewing zenith angle increases; however, it may not increase as monthly range of viewing zenith angle decreases for the same monthly image number. For similar monthly range of viewing zenith angle, the errors can vary from 45% and 340% in visible and near-infrared bands, respectively. Such a behavior is similar in both bands. When monthly image number and range of viewing zenith angle are larger than 6 and 17°, respectively, the retrieved errors in visible and near-infrared bands can be reduced be 9.5% and 43.5%, respectively. Besides, the error in near-infrared band is larger than that in visible band due to its larger error of atmospheric correction. Hence, larger error exists in normalization of the multi-temporal and multi-angular SPOT images.