Co-Registration of Terrestrial and Uav-Based Images – Experimental Results

Abstract

ABSTRACT:For many applications within urban environments the combined use of images taken from the ground and from unmanned aerial platforms seems interesting: while from the airborne perspective the upper parts of objects including roofs can be observed, the ground images can complement the data from lateral views to retrieve a complete visualisation or 3D reconstruction of interesting areas. The automatic co-registration of air-and ground-based images is still a challenge and cannot be considered solved. The main obstacle is originating from the fact that objects are photographed from quite different angles, and hence state-of-the-art tie point measurement approaches cannot cope with the induced perspective transformation. One first important step towards a solution is to use airborne images taken under slant directions. Those oblique views not only help to connect vertical images and horizontal views but also provide image information from 3D-structures not visible from the other two directions. According to our experience, however, still a good planning and many images taken under different viewing angles are needed to support an automatic matching across all images and complete bundle block adjustment. Nevertheless, the entire process is still quite sensible -the removal of a single image might lead to a completely different or wrong solution, or separation of image blocks. In this paper we analyse the impact different parameters and strategies have on the solution. Those are a) the used tie point matcher, b) the used software for bundle adjustment. Using the data provided in the context of the ISPRS benchmark on multi-platform photogrammetry, we systematically address the mentioned influences. Concerning the tie-point matching we test the standard SIFT point extractor and descriptor, but also the SURF and ASIFT-approaches, the ORB technique, as well as (A)KAZE, which are based on a nonlinear scale space. In terms of pre-processing we analyse the Wallis-filter. Results show that in more challenging situations, in this case for data captured from different platforms at different days most approaches do not perform well. Wallis-filtering emerged to be most helpful especially for the SIFT approach. The commercial software pix4dmapper succeeds in overall bundle adjustment only for some configurations, and especially not for the entire image block provided.

A new productive framework for point‐based matching of oblique aircraft and UAV‐based images

“…Note that the results of those approaches were reported by Gerke et al. (2016) and B. Wu et al. (2018).…”

“…In this part, the results of the proposed framework are compared with the results reported by Gerke et al. (2016) and B. Wu et al. (2018).…”

Automated Co-Registration of Intra-Epoch and Inter-Epoch Series of Multispectral Uav Images for Crop Monitoring

“…SURF and KAZE obtained subpixel registration accuracies but SURF was observed to be faster. KAZE employs the additive operator splitting, which has been reported to be quite inefficient (Gerke, Nex, & Jende, 2016). On the other hand, KAZE is more rigorous in feature detection than SURF.…”

Quality Features for the Integration of Terrestrial and Uav Images

“…• Registration methods based on automated 2D-2D or 3D-3D correspondence extraction: they focus on the development / improvement of new tie point or 3D feature matching extraction approaches (Tombari and Remondino, 2013;Gerke et al 2016;Koch et al, 2016;Wu et al, 2018);…”