Empirical method for topographic correction in aerial photographs

Abstract—We suggest an empirical method to correct topo-graphic effects on vegetation classification of panchromatic aerial photographs. The method is based on the use of spatial interpo-lation technique that constructs a luminance surface from targets of high brightness values. The luminance surface is then used to correct the topographic effects differentially, by increasing bright-ness values in shaded areas and decreasing brightness values of lightened areas. For this purpose, the use of a trapezoidal function was found successful in the reduction of standard deviation of brightness values of trees, shrubs, and herbaceous plants after empirical correction. This method outperformed a frequently used digital elevation model-based topographic correction in terms of overall classification accuracy of the resulting images. Index Terms—Classification error, geostatistics, topographic effect, vegetation mapping