Remote sensing: Digital image processing (3/3)
After the acquisition of satellite images, these must undergo processing: Radiometric correction: it consists in correcting the errors produced by sensor imperfections, the effect of the atmosphere ... The correction of these errors is based on mathematical models, or else an algebraic correction (we subtract for example a minimum radiometric value of all pixels). Georeferentiation: this is a geometric transformation. This process aims to coincide the image coordinate system with a reference system. This corrects the image of the effect of the relief and the tilt of the aerial platform. So that it can be superimposed on a topographic map. Like any geometric transformation, a resampling is necessary, as the extent of the pixels is modified and therefore a radiometric value must be associated with the new pixels, the choice of the resampling technique depends on the purpose of the study: - Nearest neighbor: allows you to associate with each new pixel the value of the ...