Abstract
The efficiency and high mobility of Unmanned Aerial Vehicle (UAV) made them essential to aerial photography assisted survey and mapping. Especially for urban land use and land cover, that they often changes, and need UAVs to obtain new terrain data and the new changes of land use. This study aims to collect image data and three dimensional ground control points in Taichung city area with Unmanned Aerial Vehicle (UAV), general camera and Real-Time Kinematic with positioning accuracy down to centimetre. The study area is an ecological park that has a low topography which support the city as a detention basin. A digital surface model was also built with Agisoft PhotoScan, and there will also be a high resolution orthophotos. There will be two conditions for this study, with or without ground control points and both were discussed and compared for the accuracy level of each of the digital surface models. According to check point deviation estimate, the model without ground control points has an average two-dimension error up to 40 centimeter, altitude error within one meter. The GCP-free RTK-airborne approach produces centimeter-level accuracy with excellent to low risk to the UAS operators. As in the case of the model with ground control points, the accuracy of x, y, z coordinates has gone up 54.62%, 49.07%, and 87.74%, and the accuracy of altitude has improved the most.
Highlights
IntroductionLandslides are gravitational mass movements of rock, debris or earth [Glade, T., etc., 2012]
1.1 BackgroundLandslides are gravitational mass movements of rock, debris or earth [Glade, T., etc., 2012]
With the establishment of Real-Time Kinematic (RTK) networks, one can work with a RTK rover within these networks without the need of setting up own basestation Network RTK generally requires a recommended minimum of five reference stations with an inter-station spacing of up to 70 km Network RTK has been implemented in several ways such as Master-Auxiliary Concept (MAC), Virtual Reference Station (VRS) and Flächenkorrekturparameter (FKP)
Summary
Landslides are gravitational mass movements of rock, debris or earth [Glade, T., etc., 2012] They constitute a major natural hazard in all hilly or mountainous regions throughout the world [Hölbling D., 2012]. A key parameter in engineering measures and disaster management of landslides is the earthwork volume [iiiChen, Z., etc.,2014] This parameter can be used to predict secondary hazards, such as debris flows and dammed lakes. This work reports the study of UP measurements for the determination of landslide volume in which the GCPs are measured by means of GNSS and VBS-RTK They are evaluated against four criteria, namely the earthwork volume accuracy, turnaround time, cost and personnel safety. UP with complete absence of on-ground GCP is evaluated as well
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