DEVELOPMENT OF A SIMPLE METHODOLOGY FOR GEOREFERENCING AND DISTANCE MEASURING FROM SYSTEMATIC GEOREFERENCED SATELLITE IMAGES
One of the main problems for a precise georeferencing and distance measurements from satellite images, especially in geographical zones with strong morphologic and environmental dynamics, lies not only in the difficulty for identifying ground control points (GCPs), but also in real limitations for accessing such places. In this work a relatively simple methodology is proposed for georeferencing and distance measuring from satellite images, based on the utilization of previously calculated reflectance images from the surface and then oriented toward the north (systematic georeferencing). From these images and setting a basic control point (pixel) P, measured with GPS, the other GCPs were obtained by measurements of distances defined from the P point to representative points (pixels) on the image, selected for its georeferencing. The statistical validation of the obtained results, using a different sample of GCPs measured with GPS, shows that the precision of the georeferencing and distance measurement utilizing the developed methodology is similar to that obtained by conventional procedures, such as image georeferencing from GPS data.
Satellite images; Radiometry; Georeferencing; Distance measurements; Statistical errors
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