Study On Constructing Index Of Vegetation Canopy Shadow And Its Remote Sensing Calculation Method

Vegetation is the collection of plant communities covered in a certain area and is an important part of the global eco-environmental system.With the obstruction of terrain and trees,vegetation shadow exists because little light energy can reach the area,which reduces the amount of information of ground objects.It greatly interferes with the identification of land objects,the extraction of spectral information,and the construction of quantitative algorithms.It is extremely important to study vegetation light canopy and shadow canopy for Spectral Biology under stressed vegetation.The article takes the Wangyedian Forest Farm in Chifeng City,Inner Mongolia,as the research area and takes the two typical artificial tree species of Pinus tabulaeformis and Larix as the main research object.The relationship between the reflectance and the slope at the red edge of the shadow canopy spectral and the vegetation index NDVI are studied based on the measured data of unmanned aerial vehicle(UAV).The Sentinel-2A data simulated by UAV data using the spectral response function is also used to verify the research and Normalized Difference Shadow Canopy Index(NDCSI)is constructed.The UAV hyperspectral measurement and Sentinel-2A&Landsat8-OLI satellite data are used to calculate the FVC of vegetation light canopy based on the pixel dichotomy and the NDCSI-BSI pixel ternary model.In addition,sufficient samples are used to evaluate the result.The results show that:1)Vegetation canopy NDVI value is slightly affected by the degree of shadow Moreover,the vegetation canopy red edge parameter can quantitatively express the degree of vegetation canopy brightness/shadow,which is slightly affected by different tree species information2)The correlation between the calculated FVC of vegetation light canopy and measured light illumination has a good R2 of 0.8862 based on the pixel dichotomy model.In addition,R2 of Sentinel-2A&Landsat8-OLI data reaches to 0.8475 and 0.8035 with the NDCSI-BSI pixel ternary model.3)The constructed NDCSI can quantitatively express the shadow/light level of the vegetation canopy.Combined with suitable vegetation index,the FVC of vegetation shadow canopy and light canopy can be estimated with high precision.