Geometric accuracy assessment of remotely sensed imagery
Remotely sensed imagery is affected by distortions mainly caused by remote sensing platform, sensor, atmosphere, and topographic features on the surface. In order to correct these effects several methods may apply such as registration and orthorectification geometric correction. The aim of this paper is to apply a registration and orthorectification method to a high resolution image as a measure of accuracy enhancement within both techniques. To do so, images from the Geoeye-1 satellite/sensor are used, which panchromatic band has 0.5 m and multispectral bands have 2 m of spatial resolution. Ground Control Points – GCPs and a stereopar Digital Elevation Model – DEM (2 m spatial resolution) extracted for the same image are also used. Both images were classified and statiscally compared to a RapidEye satellite/sensor image. The area of interest is located in the Carajás Mining Complex, in the municipality of Parauapebas, state of Pará – Brazil. Results have shown that location shifts are present between the registered and orthorectified image. There are also differences in the total area of each class, mostly on steep terrain. The statistical analysis has proved that there is improvement in the use of the orthorectification process at a 5% significance level. Thus, we could conclude that the orthorectification process is an important step on image geometric correction, contributing to enhance image metrics, morphology, and even so location accuracy.