Stable Imaging and Accuracy Issues of Low-Altitude Unmanned Aerial Vehicle Photogrammetry Systems

Ying Yang,Zongjian Lin,Fengzhu Liu

doi:10.3390/rs8040316

Abstract

Stable imaging of an unmanned aerial vehicle (UAV) photogrammetry system is an important issue that affects the data processing and application of the system. Compared with traditional aerial images, the large rotation of roll, pitch, and yaw angles of UAV images decrease image quality and result in image deformation, thereby affecting the ground resolution, overlaps, and the consistency of the stereo models. These factors also cause difficulties in automatic tie point matching, image orientation, and accuracy of aerial triangulation (AT). The issues of large-angle photography of UAV photogrammetry system are discussed and analyzed quantitatively in this paper, and a simple and lightweight three-axis stabilization platform that works with a low-precision integrated inertial navigation system and a three-axis mechanical platform is used to reduce this problem. An experiment was carried out with an airship as the flight platform. Another experimental dataset, which was acquired by the same flight platform without a stabilization platform, was utilized for a comparative test. Experimental results show that the system can effectively isolate the swing of the flying platform. To ensure objective and reliable results, another group of experimental datasets, which were acquired using a fixed-wing UAV platform, was also analyzed. Statistical results of the experimental datasets confirm that stable imaging of a UAV platform can help improve the quality of aerial photography imagery and the accuracy of AT, and potentially improve the application of images acquired by a UAV.

Highlights

Unmanned aerial vehicles (UAV), as a flexible aerial photography platform, have been widely used in many applications, such as agriculture, water conservation, geophysical exploration, mapping, 3D reconstruction, and disaster relief [1,2,3,4,5,6,7,8]
As a supplementary photogrammetry platform for satellite and traditional aerial photogrammetry systems, low-altitude UAV has several advantages, such as low altitude, low speed, low cost, flexible and simple operation, and high-resolution images [9]
Datasets, which were acquired by the same flight platform with the same camera system, are employed to demonstrate the influence of rotation angle on image resolution, overlaps, distribution and accuracy of tie points, and aerial triangulation (AT) and and stereo model, model, and the results indicate the feasibility and accuracy of the precision of the AT

Summary

Introduction

Unmanned aerial vehicles (UAV), as a flexible aerial photography platform, have been widely used in many applications, such as agriculture, water conservation, geophysical exploration, mapping, 3D reconstruction, and disaster relief [1,2,3,4,5,6,7,8]. As a supplementary photogrammetry platform for satellite and traditional aerial photogrammetry systems, low-altitude UAV has several advantages, such as low altitude, low speed (for a low-altitude aerial photography system, high speed will result in a blurred image), low cost, flexible and simple operation, and high-resolution images [9]. The tilt angle of the images for a traditional aerial photogrammetry platform is not more than 3 ̋ , but for a low-altitude UAV platform, the typical unstable flight attitude may lead to a large rotation angle in photography. A light and small UAV and an unmanned airship platform are not as reliable as the traditional aerial photography system, and are more likely to be affected by wind and other weather factors, the rotation

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Methods

Discussion

Conclusion