Generating a High-Precision True Digital Orthophoto Map Based on UAV Images

Liu, Yu; Zheng, Xinqi; Ai, Gang; Zhang, Yi; Zuo, Yuqiang

doi:10.3390/ijgi7090333

Cited by 63 publications

(42 citation statements)

References 27 publications

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“…In particular, UAV photogrammetry has been used to acquire 3D numerical data across a wide area, which, when combined with terrestrial laser scanning data, provides a large number of point clouds; this reduces the time required for data acquisition. In this respect, studies on the digital documentation of cultural heritage sites using different technologies have been conducted in conjunction with the deployment of UAV [43][44][45][46][47]. In this paper, we focused on evaluating the reliability of the point data obtained via terrestrial laser scanning and UAV photogrammetry to enhance the convergent usability of both datasets by comparing the position accuracy of the point cloud data.…”

Section: Accuracy Assessmentmentioning

confidence: 99%

Three-Dimensional Digital Documentation of Cultural Heritage Site Based on the Convergence of Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry

Hong

2019

IJGI

140

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Three-dimensional digital technology is important in the maintenance and monitoring of cultural heritage sites. This study focuses on using a combination of terrestrial laser scanning and unmanned aerial vehicle (UAV) photogrammetry to establish a three-dimensional model and the associated digital documentation of the Magoksa Temple, Republic of Korea. Herein, terrestrial laser scanning and UAV photogrammetry was used to acquire the perpendicular geometry of the buildings and sites, where UAV photogrammetry yielded higher planar data acquisition rate in upper zones, such as the roof of a building, than terrestrial laser scanning. On comparing the two technologies’ accuracy based on their ground control points, laser scanning was observed to provide higher positional accuracy than photogrammetry. The overall discrepancy between the two technologies was found to be sufficient for the generation of convergent data. Thus, the terrestrial laser scanning and UAV photogrammetry data were aligned and merged post conversion into compatible extensions. A three-dimensional (3D) model, with planar and perpendicular geometries, based on the hybrid data-point cloud was developed. This study demonstrates the potential for using the integration of terrestrial laser scanning and UAV photogrammetry in 3D digital documentation and spatial analysis of cultural heritage sites.

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Section: Accuracy Assessmentmentioning

confidence: 99%

Three-Dimensional Digital Documentation of Cultural Heritage Site Based on the Convergence of Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry

Hong

2019

IJGI

140

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“…Flight endurance is higher for fixed-wings (≥45 min). Multi-rotors have a short flight time of~20-30 min (Tahar 2015;Mesas-Carrascosa et al 2016;Liu et al 2018;Ventura et al 2018), due to their vertical take-off and landing (VTOL) capability. The range of fixed-wings often exceeds that of multi-rotors (Rees et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Influence of altitude on tropical marine habitat classification using imagery from fixed‐wing, water‐landing UAVs

Ellis

Taylor

Schiele

et al. 2020

Remote Sens Ecol Conserv

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Unmanned aerial vehicles (UAVs) are cost-effective remote sensing tools useful for generating very high-resolution (VHR) aerial imagery. Habitat maps generated from UAV imagery are a fundamental component of marine spatial planning, essential for the designation and governance of marine protected areas (MPAs). We investigated whether UAV survey altitude affects habitat classification performance and the classification accuracy of thematic maps from a tropical shallow water environment. We conducted repeated UAV flights at 75, 85, and 110 m, using a fixed-wing UAV on the Turneffe Atoll, Belize. Flights were ground truthed with snorkel surveys. Images were mosaiced to form orthomosaics and transformed into thematic maps through semi-automatic object-based image analysis (OBIA). Three subset areas (4000 m 2 , 17 000 m 2 and 17 000 m 2) from two cayes on the atoll were selected to investigate the effect of survey altitude. A linear regression demonstrated that for every 1 m increase in survey altitude, there was a~1% decrease in the overall classification accuracy. A low survey altitude of 75 m produced a higher classification accuracy for thematic maps and increased the representation of mangrove, seagrass and sand. The variability in classified cover was driven by altitude, although the direction and extent of this relationship was specific to each class. For coral and sea, classified cover decreased with increased altitude. Mangrove classified cover was non-sensitive to altitude changes, demonstrating a lesser need for a consistent survey altitude. Sand and seagrass had a greater sensitivity to altitude, due to classified cover variability between altitudes. Our findings suggest that survey altitude should be minimized when classifying tropical marine environments (coral, seagrass) and, given that most fixed-wing UAVs are restricted to a minimum altitude of 70 m, we recommend an altitude of 75 m. Survey altitude should be a major consideration when targeting habitats with greater sensitivity to altitude variability.

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“…Pix4D uses structure from motion (SfM) photogrammetry for 3D natural environment reconstructions [50]. This generates an orthomosaic and a digital surface model (DSM) that we used to identify height values within the quadrats [51]. We reported the mean (X, Y, Z) root mean square error (RMSE) for each flight.…”

Section: Image Processing and Volume Estimationmentioning

confidence: 99%

A Pilot Study to Estimate Forage Mass from Unmanned Aerial Vehicles in a Semi-Arid Rangeland

et al. 2020

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The application of unmanned aerial vehicles (UAVs) in the monitoring and management of rangelands has exponentially increased in recent years due to the miniaturization of sensors, ability to capture imagery with high spatial resolution, lower altitude platforms, and the ease of flying UAVs in remote environments. The aim of this research was to develop a method to estimate forage mass in rangelands using high-resolution imagery derived from the UAV using a South Texas pasture as a pilot site. The specific objectives of this research were to (1) evaluate the feasibility of quantifying forage mass in semi-arid rangelands using a double sampling technique with high-resolution imagery and (2) to compare the effect of altitude on forage mass estimation. Orthoimagery and digital surface models (DSM) with a resolution <1.5 cm were acquired with an UAV at altitudes of 30, 40, and 50 m above ground level (AGL) in Duval County, Texas. Field forage mass data were regressed on volumes obtained from a DSM. Our results show that volumes estimated with UAV data and forage mass as measured in the field have a significant relationship at all flight altitudes with best results at 30-m AGL (r2 = 0.65) and 50-m AGL (r2 = 0.63). Furthermore, the use of UAVs would allow one to collect a large number of samples using a non-destructive method to estimate available forage for grazing animals.

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Generating a High-Precision True Digital Orthophoto Map Based on UAV Images

Cited by 63 publications

References 27 publications

Three-Dimensional Digital Documentation of Cultural Heritage Site Based on the Convergence of Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry

Three-Dimensional Digital Documentation of Cultural Heritage Site Based on the Convergence of Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry

Influence of altitude on tropical marine habitat classification using imagery from fixed‐wing, water‐landing UAVs

A Pilot Study to Estimate Forage Mass from Unmanned Aerial Vehicles in a Semi-Arid Rangeland

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