Multimodal Remote Sensing Image Registration with Accuracy Estimation at Local and Global Scales

This paper focuses on potential accuracy of remote sensing images registration. We investigate how this accuracy can be estimated without ground truth available and used to improve registration quality of mono- and multi-modal pair of images. At the local scale of image fragments, the Cramer-Rao lower bound (CRLB) on registration error is estimated for each local correspondence between coarsely registered pair of images. This CRLB is defined by local image texture and noise properties. Opposite to the standard approach, where registration accuracy is only evaluated at the output of the registration process, such valuable information is used by us as an additional input knowledge. It greatly helps detecting and discarding outliers and refining the estimation of geometrical transformation model parameters. Based on these ideas, a new area-based registration method called RAE (Registration with Accuracy Estimation) is proposed. In addition to its ability to automatically register very complex multimodal image pairs with high accuracy, the RAE method provides registration accuracy at the global scale as covariance matrix of estimation error of geometrical transformation model parameters or as point-wise registration Standard Deviation. This accuracy does not depend on any ground truth availability and characterizes each pair of registered images individually. Thus, the RAE method can identify image areas for which a predefined registration accuracy is guaranteed. The RAE method is proved successful with reaching subpixel accuracy while registering eight complex mono/multimodal and multitemporal image pairs including optical to optical, optical to radar, optical to Digital Elevation Model (DEM) images and DEM to radar cases. Other methods employed in comparisons fail to provide in a stable manner accurate results on the same test cases.Comment: 48 pages, 8 figures, 5 tables, 51 references Revised arguments in sections 2 and 3. Additional test cases added in Section 4; comparison with the state-of-the-art improved. References added. Conclusions unchanged. Proofrea

Surface displacements in the September 2005 Afar rifting event from satellite image matching: Asymmetric uplift and faulting

Combining sub‐pixel analysis of SPOT4 images with InSAR measurements, we generate 3D surface displacements for the September 2005 rifting event on the Dabbahu Segment in the Afar valley. The axis of rifting in the event is shifted to the east of the geomorphic rift. The horizontal displacements reveal 6 m of extension, and vertical displacements show asymmetric uplift of the flanks of the dike. Simple forward modelling indicates this asymmetry is due to the dike dipping 80° to the west towards the geomorphic rift. The boundary between eastward and westward displacements aligns with the transition between uplift and subsidence on the east in the north part of the segment, but on the west in the south. Normal faulting is not required on both sides of the instantaneous rift. East‐dipping normal faulting on the west side of the instantaneous rift aligns with a west‐dipping normal fault in the topography