Analysis And Evaluation Of Topographic Elimination Performance For Topography-adjusted Vegetation Index (TAVI)

Topography-adjusted vegetation index (TAVI) provides a new effective method for monitoring vegetation information in rugged areas, for it can without the support of data from other resources and its strong operability. Based on the basic theory, multispectral remote sensing images from different regions and different platforms were used to conduct the experiment about the topographic effect elimination performance of TAVI. The main content of this paper is as follows:(1) The verification of topographic elimination effect of TAVI. Four regions (Fujian sample region, Jilin sample region, Yunnan sample region and Tibet sample region) of great topography differences and multispectral remote sensing images (Landsat5/TM、 Alos/AVNIR-2. IRS-P6/LISS3、HJ-1A/CCD1) from different sensors were chosen as research areas and experimental data respectively to conduct the experiment of topographic elimination effect for TAVI. Compared with NDVI, TAVI has a wider dynamic range value, therefore, TAVI can identify more abundant vegetation information. Meanwhile, TAVI image has a smaller difference between shadow slope and sunny slope. Therefore, TAVI can better reflect the real vegetation information. According to visual effect、comparative analysis of statistical indicators and linear fitting with solar incident angle cosine power, the results show that TAVI can eliminate topography texture remarkably.(2) The implementation and comparison for four terrain radiation correction algorithms. Based on interactive data language, conventional four terrain radiation correction algorithms (Cosine correction, C correction, SCS correction, SCS+C correction) were realized and compared. SCS+C were proved to be the best correction algorithm. Meanwhile, the NDVI (normalized difference vegetation index) images after SCS+C correction algorithm were compared with TAVI. The results show that TAVI has a better effect in eliminating topography textures in all kinds of terrain.(3) The analysis of topography texture elimination ability for TAVI. TAVI can eliminate complex topography textures remarkably, its performance have nothing to do with remote sensing data source、spatial resolution and solar incident angle, only related to different kinds of terrains. the results show TAVI has obvious topographic elimination effect in all kinds of terrains especially in flat regions(slope less than 30°), While, topographic elimination effects may decreased in very rugged high mountain areas where altitude difference between 300-400m and slope larger than 30°.