Multi-Camera Imaging System for UAV Photogrammetry.

Damian Wierzbicki

doi:10.3390/s18082433

Abstract

In the last few years, it has been possible to observe a considerable increase in the use of unmanned aerial vehicles (UAV) equipped with compact digital cameras for environment mapping. The next stage in the development of photogrammetry from low altitudes was the development of the imagery data from UAV oblique images. Imagery data was obtained from side-facing directions. As in professional photogrammetric systems, it is possible to record footprints of tree crowns and other forms of the natural environment. The use of a multi-camera system will significantly reduce one of the main UAV photogrammetry limitations (especially in the case of multirotor UAV) which is a reduction of the ground coverage area, while increasing the number of images, increasing the number of flight lines, and reducing the surface imaged during one flight. The approach proposed in this paper is based on using several head cameras to enhance the imaging geometry during one flight of UAV for mapping. As part of the research work, a multi-camera system consisting of several cameras was designed to increase the total Field of View (FOV). Thanks to this, it will be possible to increase the ground coverage area and to acquire image data effectively. The acquired images will be mosaicked in order to limit the total number of images for the mapped area. As part of the research, a set of cameras was calibrated to determine the interior orientation parameters (IOPs). Next, the method of image alignment using the feature image matching algorithms was presented. In the proposed approach, the images are combined in such a way that the final image has a joint centre of projections of component images. The experimental results showed that the proposed solution was reliable and accurate for the mapping purpose. The paper also presents the effectiveness of existing transformation models for images with a large coverage subjected to initial geometric correction due to the influence of distortion.

Highlights

Multi-camera systems, and the nadir and oblique images acquired by them, are of increasing importance in professional aerial photogrammetry
The results presented in the aforementioned articles summarize the experience associated with using digital cameras for photogrammetric measurements
Increasing efficiency in obtaining oblique images from unmanned aerial vehicles (UAV) was observed during research work carried out previously [2]

Summary

Introduction

Multi-camera systems, and the nadir and oblique images acquired by them, are of increasing importance in professional aerial photogrammetry. In comparison with classical photogrammetry, nadir and oblique imaging technology allow for the registration of footprints and building facades. It is possible to simplify the identification and interpretation of some objects that are difficult to recognize from the unique perspective view [1,2]. Oblique images can be used to fill the existing gap between aerial images and terrestrial images [3]. Professional photogrammetry cameras are capable of mapping large areas. Multisite imaging systems Microsoft Vexcel UltraCam [4]

Methods

Results

Discussion

Conclusion