Rigorous radiometric calibration of airborne AeS-1 InSAR data

SAR Radiometric Calibration Based on Differential Geometry: From Theory to Experimentation on SAOCOM Imagery

“…Some considerations on the comparison of the adopted method with respect to other SAR calibration algorithms are in order. Indeed, comparing the results obtained with the diverse existing radiometric calibration approaches [2][3][4][5][6][7][8][9] is not a simple task, insofar as they may include different assumptions, parameters, and specific algorithmic implementations, as noted, for instance, in [35]. Consequently, a consistent and meaningful assessment might be generally difficult to obtain with a superficial direct comparison.…”

“…The geometric interpretation of ( 9) is therefore pictorially shown in Figure 3. Notice that ∆r g = ∆r g (r) varies across the scene from near to the far range, according to (9). In this special case, the area of the patch on the ground, ∆A g = ∆r g ∆a, corresponding to a prescribed rectangular element, ∆A image = ∆r∆a, in the SAR image domain is consistently given by…”

“…As sketched in Figure 4, ∆r g denotes the ground-range increment associated with ∆r, with ∆θ representing the angle subtended by ∆r g . By substituting (13) in (9), it turns out that ∆r g = ∆r/sin θ. Accordingly, from (14), ∆r g cos θ = r∆θ is simply obtained.…”

“…By contrast, scene-dependent radiometric distortions arise from the inherent 2D imaging process of a 3D irregular ground shape, and they are inherently local in nature [2][3][4][5][6][7][8][9][10][11]. Accordingly, the 2D imaging process of an irregular relief intrinsically implies unavoidable radiometric distortions.…”

“…Regarding topography-induced SAR radiometric distortions, some calibration approaches are available in the literature [2][3][4][5][6][7][8][9][10]. More recently, an effective method for radiometric calibration derived in the rigorous framework of differential geometry of the surfaces has been developed, and it exhibits important advantages [10,17].…”