Abstract
The aim of the topographic normalization of remotely sensed imagery is to reduce reflectance variability caused by steep terrain and thus improve further processing of images. A process of topographic correction was applied to Landsat imagery in a mountainous forest area in the south of Mexico. The method used was the Sun Canopy Sensor + C correction (SCS + C) where the C parameter was differently determined according to a classification of the topographic slopes of the studied area in nine classes for each band, instead of using a single C parameter for each band. A comparative, visual, and numerical analysis of the normalized reflectance was performed based on the corrected images. The results showed that the correction by slope classification improves the elimination of the effect of shadows and relief, especially in steep slope areas, modifying the normalized reflectance values according to the combination of slope, aspect, and solar geometry, obtaining reflectance values more suitable than the correction by non-slope classification. The application of the proposed method can be generalized, improving its performance in forest mountainous areas.
Highlights
To have a digital elevation model (DEM) and a derived slope map is relatively easy; it would be easier to develop the proposed method seeking to improve the topographical correction without relying on a land cover map
With the C(i,j) parameters obtained in each case (SC and N-SC), the SCS + C topographic correction method was applied, and normalized-reflectance images have been achieved for each band
The global C(i) parameters calculated by N-SC have less variation compared to those calculated by SC, which follows that the resulting reflectance values after N-SC and SC corrections are more similar to each other
Summary
The determination of the reflectance value of the surface by removing topographic effects is an important task in remote sensing studies [1]. The ability to provide reliable information through satellite imagery is constrained by the effects that changes in slope and terrain orientation angles (aspect) in combination to the solar geometry (zenithal and azimuthal angles) at the time of the image acquisition cause on the spectral direct and diffuse irradiance [2] This occurs especially in mountainous areas where slope surfaces directly oriented to sun rays receive more light and appear brighter in images than those surfaces that are not receiving the sunlight directly [3]. Teillet et al [4] state that the C-parameter exerts a moderating influence on cosine correction method by increasing the denominator and reduce overcorrection of dimly lit pixels This adjustment has shown that the spectral characteristics of data are retained and improves the classification accuracy in mountainous areas [18,19]. To have a digital elevation model (DEM) and a derived slope map is relatively easy; it would be easier to develop the proposed method seeking to improve the topographical correction without relying on a land cover map
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
