ORTHORECTIFICATION OF CEBERS 2 IMAGES USING THE DLT TRANSFORMATION

Abstract

This work evaluates the orthoimages generation potentiality of the CCD sensor from the CBERS 2, by using a generalized mathematical model called “Direct Linear Transformation (DLT)”. Two Digital Elevation Models (DEM's) sources of altimetry information data for the orthoimages generations were used: the first generated from SRTM mission and the other one developed from contour lines and topographic points counted in a 1:50.000 scale. An orthorretification process of a cutting out scene from the CBERS was performed with both DEM´s. The images were analyzed and classified according to the Padrão de Exatidão Cartográfica (PEC) using check points. To evaluate the necessity of orthorefications in the CCD CBERS 2 scene, the same cutting out was also object of geometric corrections having a second degree polynomial as a tool. The planimetrics residues generated by the second degree polynomial simplified corrections were just enough to demonstrate the necessity of the orthoretification process, that is, corrections of errors due to the embossment topography at the considered scene. The comparison of the images produced by the different DEM´s demonstrates that the utilization of the DEM from the SRTM is a satisfactory tool for images orthoretifications of the CBERS 2