Extraction of BRDF characteristics using TM/ETM+and DEM data
基于TM/ETM和DEM数据的BRDF特征提取

We propose a method to extract the feature of Bi-directional Reflectance Distribution Functions (BRDF) over BadainJaran Desert using Landsat-TM/ETM+and ASTER GDEM data. Badain Jaran Desert is characterized with homogeneous andrugged terrain, which forms a natural Bi-directional Reflectance data sets with hypotheses that the surface structure of eachslope element does not vary with the variations of slope and aspect. Therefore, we use nadir view Landsat-TM/ETM+imageryto reconstruct the BRDF characterization of this experimental site. To begin with we use ASTER GDEM product to retrieve thesun-view geometry for each slope element corresponding to one pixel in remotely sensed imagery. Then the observations fromLandsat-TM/ETM+imagery and the retrieved sun-view geometries are used together to extract the BRDF feature of the experimentalsite. Finally, we simulate surface reflectance for 25 scenes of different Landsat-TM and ETM+images and compare thesimulations with the actual Landsat-TM and ETM+imageries. Results show that the difference between the simulation and "true"surface reflectance are 2.80%, 1.92%, 2.68% and 2.32%, respectively, which is higher than the radiometric calibration error requirementof 5% to 7%. Therefore, the combination of nadir viewing Landsat-TM/ETM+imagery with ASTER GDEM data canbe used to cross-calibrate remotely sensed imagery with large viewing observation.