Remote Sensing Inversion Of Vegetation Cover Parameters Based On Topographic Radiation Correction

Remote sensing as a long distance and non-contact way to obtain the surface information attract more and more people's attention.In the analysis of spectral information of remote sensing images,quantitative remote sensing has always been an important research direction of the people.The satellite get the ground image at high altitude which inevitably affected by the electromagnetic wave,atmosphere and terrain factors.One of the important factors that affect the image quality is the change of the spectral information which result in topographic relief.Topographic relief lead to the shelter of sunlight,the no reflection of sunlight in the shady slope,the weakness of texture features,the interpretation of images,the decline of the classification precision and many other remote sensing analysis processes.Therefore,the restoration of image spectral information based on terrain radiometric correction is an indispensable step to acquire the real spectral information accurately by remote sensing.Firstly,this paper introduces the research background and the status of terrain radiation correction,and then uses the ENVI to carry out atmospheric correction and geometric correction for images.Secondly,using the MATLAB to code and process which include the C correction,SCS+C correction,Minnaert-SCS correction,Teillet-regression correction and VECA correction.Then introducing a semi empirical parameter C to improve the MinnaertSCS model,which will avoid excessive correction when the solar incident angle cosi is too small,and comparing the correction result with other method after encoding processing.Lastly,four vegetation index,including RVI,NDVI,EVI,MSAVI,was extracted and compared.The vegetation coverage of these four vegetation indices was calculated by means of dimidiate pixel method,and the influence of topographic correction on vegetation coverage inversion was analyzed.Through the experiment and comparison,the improved correction method can enhance the correction effect of the shadow region under the effect of topography and low luminance region and eliminate most of the reflectance difference between the sunny and shady slope.Through the visual comparison and statistical analysis of the data,the improved model shows a better correction effect.On the other hand,the topographic correction improves vegetation coverage based on EVI,and has little effect on vegetation coverage based on RVI,NDVI and MSAVI.Therefore,it is recommended to carry out topographic correction when using the EVI to estimate vegetation coverage.