An Image-Based Approach for the Co-Registration of Multi-Temporal UAV Image Datasets

Abstract

During the past years, UAVs (Unmanned Aerial Vehicles) became very popular as low-cost image acquisition platforms since they allow for high resolution and repetitive flights in a flexible way. One application is to monitor dynamic scenes. However, the fully automatic co-registration of the acquired multi-temporal data still remains an open issue. Most UAVs are not able to provide accurate direct image georeferencing and the co-registration process is mostly performed with the manual introduction of ground control points (GCPs), which is time consuming, costly and sometimes not possible at all. A new technique to automate the co-registration of multi-temporal high resolution image blocks without the use of GCPs is investigated in this paper. The image orientation is initially performed on a reference epoch and the registration of the following datasets is achieved including some anchor images from the reference data. The interior and exterior orientation parameters of the anchor images are then fixed in order to constrain the Bundle Block Adjustment of the slave epoch to be aligned with the reference one. The study involved the use of two different datasets acquired over a construction site and a post-earthquake damaged area. Different tests have been performed to assess the registration procedure using both a manual and an automatic approach for the selection of anchor images. The tests have shown that the procedure provides results comparable to the traditional GCP-based strategy and both the manual and automatic selection of the anchor images can provide reliable results.

Testing Accuracy and Repeatability of UAV Blocks Oriented with GNSS-Supported Aerial Triangulation

“…Production and updating of large scale maps (including cadastral ones [19]) have also seen a shift from manned to unmanned aerial surveys, with demand for larger and larger areas to be covered. Use of UAVs in the survey of terrain movements, such as in landslides [20,21], glaciers [22,23] and geomorphology [24], is also expanding.…”

Automatic UAV Image Geo-Registration by Matching UAV Images to Georeferenced Image Data

“…However, only low altitudes and oblique images facing building facades are considered for the geo-registration. Aicardi et al [32] adopts an image-based approach for co-registering multi-temporal UAV image datasets; however, it only estimates the relative transformation between the epochs, while the absolute transformation of the epoch is not solved. Finally, Xu et al [33] presents an fast and efficient way for UAV image mosaicking without the explicit computation of camera poses; however, the image mosaics are not geo-registered.…”

A New Propagation Channel Synthesizer for UAVs in the Presence of Tree Canopies

“…This may generally happen in the close vicinity of both the UAV and its ground terminal, thus directly affecting the BLoS relays as well. This can be, e.g., the case of the scenarios from [1]. To ensure proper link operation under such conditions, it is first necessary to thoroughly characterize such influence.…”