PRACTISE – Photo Rectification And ClassificaTIon SoftwarE (V.2.1)

Geoscientific Model Development

M.Bernhardt¹  K.Schulz¹  S.Härer¹ 

DOI  :  10.5194/gmd-9-307-2016

学科分类：天文学(综合)

来源: Copernicus Publications

【 摘 要 】

Terrestrial photography combined with the recently presented PhotoRectification And ClassificaTIon SoftwarE (PRACTISE V.1.0) hasproven to be a valuable source to derive snow cover maps in a hightemporal and spatial resolution. The areal coverage of the useddigital photographs is however strongly limited. Satellite images onthe other hand can cover larger areas but do show uncertainties withrespect to the accurate detection of the snow covered area. This isespecially the fact if user defined thresholds are needed, e.g. incase of the frequently used normalized-difference snow index (NDSI).The definition of this value is often not adequately definedby either a general value from literature or over the impression ofthe user, but not by reproducible independent information. PRACTISEV.2.1 addresses this important aspect and shows additionalimprovements. The Matlab-based software is now able to automaticallyprocess and detect snow cover in satellite images. A simultaneouslycaptured camera-derived snow cover map is in this case utilized asin situ information for calibrating the NDSI thresholdvalue. Moreover, an additional automatic snow cover classification,specifically developed to classify shadow-affected photographs, wasincluded. The improved software was tested for photographs andLandsat 7 Enhanced Thematic Mapper (ETM+) as well as Landsat 8Operational Land Imager (OLI) scenes in the Zugspitze massif(Germany). The results show that using terrestrial photography incombination with satellite imagery can lead to an objective,reproducible, and user-independent derivation of the NDSI thresholdand the resulting snow cover map. The presented method is notlimited to the sensor system or the threshold used in here butoffers manifold application options for other scientific branches.

【 授权许可】

Unknown