期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2006
卷号：XXXVI Part 7
出版社：Copernicus Publications
摘要：View angle effects present in vegetation indices are either being seen as unwanted information or as an additional source of information. However, the magnitude of these angular effects remains for most indices unknown. We use the ESA-mission CHRIS- PROBA (Compact High Resolution Imaging Spectrometer–Project for On-board Autonomy) providing spaceborne imaging spectrometer and multidirectional data to assess the directional sensitivity of broadband and recently developed narrowband indices. Apart from the illumination and viewing geometry as well as the atmospheric composition, the surface reflectance anisotropy is a prime factor determining indices′ directional response. Two contrasting structural vegetation types, forest and meadow, were selected to study the affect of different land cover types on the indices′ angular response. This work demonstrates that the tested broadband indices (NDVI, SRI, ARVI) as well as the narrowband indices NDVI 705 , PRI, ARI1 & ARI2 were significantly sensitive to angular effects, while other indices (mSR 705 , mNDVI 705 , SIPI & RGRI) tested invariant to multiple viewing angle observations. The results suggest that caution is required when using some, but not all, indices since angular effects may differently impact the results, finally seriously hampering interpretation
关键词：Vegetation indices; CHRIS/PROBA; multiangular; imaging spectrometer; viewing effects; Swiss National Park
