Topographic correction reduces terrain effects and improves radiation quality

such enhancements are beneficial to the improvement of computer classification accuracy in mountains. This paper designed a topographic correction method specifically for the global land cover classification of Landsat TM / ETM + data. This method first smoothens the terrain slope angle and then performs a cosine correction based on the smoothed terrain. This method effectively removes radiation abnormalities in the results of Cosine correction（ COS） and other Lambertian-based methods. This method and several other common methods

such as C

SCS

and Minnaert corrections

were tested on six Landsat TM / ETM + data from different regions of the world with different land cover types. Visual and statistical analyses were conducted to assess the performance of these methods in terms of two aspects: overcorrection and homogeneity within a land cover class. Comparison results indicate that the smoothing step significantly reduces overcorrection. This simple and effective algorithm avoid complex atmospheric parameter estimations. Engineering requirements of t errain correction for global land cover classification are met.