Short Communication: A simple workflow for robust low-cost UAV-derived change detection without ground control points

• Published in: Earth Surface Dynamics
• Main Authors: K. L. Cook, M. Dietze
• Format: Article
• Language: English
• Published: Copernicus Publications 2019-10-01
• Online Access: https://www.earth-surf-dynam.net/7/1009/2019/esurf-7-1009-2019.pdf

<p>High-quality 3-D point clouds generated from repeat camera-equipped unmanned aerial vehicle (UAV) surveys are increasingly being used to investigate landscape changes and geomorphic processes. Point cloud quality can be expressed as accuracy in a comparative (i.e., from survey to survey) and absolute (between survey and an external reference system) sense. Here we present a simple workflow for calculating pairs or sets of point clouds with a high comparative accuracy, without the need for ground control points or a differential GNSS (dGNSS)-equipped UAV. The method is based on the automated detection of common tie points in stable portions of the survey area. We demonstrate the efficacy of the new approach using a consumer-grade UAV in two contrasting landscapes: the coastal cliffs on the island of Rügen, Germany, and the tectonically active Daan River gorge in Taiwan. Compared to a standard approach using ground control points, our workflow results in a nearly identical distribution of measured changes. Compared to a standard approach without ground control, our workflow reduces the level of change detection from several meters to 10–15&thinsp;cm. This approach enables robust change detection using UAVs in settings where ground control is not feasible.</p>