Benchmarking the Optical Resolving Power of Uav Based Camera Systems

Meißner, Henry; Cramer, Michael; Piltz, Björn

doi:10.5194/isprs-archives-xlii-2-w6-243-2017

Cited by 6 publications

(4 citation statements)

References 10 publications

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“…As the FOVEON technology allows to capture all three colour channels for each individual pixel, the use of Bayer filters and following demosaicking, which is standard for all the remaining cameras, is not necessary here. The influence of image de-mosaicking is discussed and comprehensively analysed in Meißner et al (2017). As mentioned, the Phantom 3 (using TIF) shows very good performance, not only in the group of proprietary DJI systems, further confirming the previous assumption that this camera is already close to the concept of metric camera design.…”

Section: Lab Calibrationssupporting

confidence: 58%

“…Due to the fast consumer product cycles some of the investigated systems have already been re-placed by their successors. This paper can be seen in connection of the work from Meißner et al (2017) -to be submitted to this UAV-g conference -where the analysis of radiometric performance of UAV based cameras is discussed. Some of the cameras investigated from geometrical point of view here also were radiometrically analysed by Meißner et al (2017).…”

Section: Introductionmentioning

confidence: 99%

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Uav Cameras: Overview and Geometric Calibration Benchmark

Cramer

Przybilla

Zurhorst³

2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Different UAV platforms and sensors are used in mapping already, many of them equipped with (sometimes) modified cameras as known from the consumer market. Even though these systems normally fulfil their requested mapping accuracy, the question arises, which system performs best? This asks for a benchmark, to check selected UAV based camera systems in well-defined, reproducible environments. Such benchmark is tried within this work here. Nine different cameras used on UAV platforms, representing typical camera classes, are considered. The focus is laid on the geometry here, which is tightly linked to the process of geometrical calibration of the system. In most applications the calibration is performed in-situ, i.e. calibration parameters are obtained as part of the project data itself. This is often motivated because consumer cameras do not keep constant geometry, thus, cannot be seen as metric cameras. Still, some of the commercial systems are quite stable over time, as it was proven from repeated (terrestrial) calibrations runs. Already (pre-)calibrated systems may offer advantages, especially when the block geometry of the project does not allow for a stable and sufficient in-situ calibration. Especially for such scenario close to metric UAV cameras may have advantages. Empirical airborne test flights in a calibration field have shown how block geometry influences the estimated calibration parameters and how consistent the parameters from lab calibration can be reproduced.

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Section: Lab Calibrationssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Uav Cameras: Overview and Geometric Calibration Benchmark

Cramer

Przybilla

Zurhorst³

2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

Self Cite

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“…Careful planning and implementation of fixed-wing UAV missions and an effective photogrammetric workflow are both required to acquire reliable image-based point cloud data with high spatial, temporal, and spectral resolution (e.g., [67,68]). …”

Section: General Considerations For Forestry Applicationsmentioning

confidence: 99%

Evaluating the Performance of Photogrammetric Products Using Fixed-Wing UAV Imagery over a Mixed Conifer–Broadleaf Forest: Comparison with Airborne Laser Scanning

2018

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Unmanned aerial vehicles (UAVs) and digital photogrammetric techniques are two recent advances in remote sensing (RS) technology that are emerging as alternatives to high-cost airborne laser scanning (ALS) data sources. Despite the potential of UAVs in forestry applications, very few studies have included detailed analyses of UAV photogrammetric products at larger scales or over a range of forest types, including mixed conifer-broadleaf forests. In this study, we assessed the performance of fixed-wing UAV photogrammetric products of a mixed conifer-broadleaf forest with varying levels of canopy structural complexity. We demonstrate that fixed-wing UAVs are capable of efficiently collecting image data at local scales and that UAV imagery can be effectively utilized with digital photogrammetric techniques to provide detailed automated reconstruction of the three-dimensional (3D) canopy surface of mixed conifer-broadleaf forests. When combined with an accurate digital terrain model (DTM), UAV photogrammetric products are promising for producing reliable structural measurements of the forest canopy. However, the performance of UAV photogrammetric products is likely to be influenced by the structural complexity of the forest canopy. Furthermore, we highlight the potential of fixed-wing UAVs in operational forest management at the forest management compartment level, for acquiring high-resolution imagery at low cost. A future direction of this research would be to address the issue of how well the photogrammetric products can predict the actual structure of mixed conifer-broadleaf forests.

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“…As a result of this sensor technique, the images have better micro-contrast compared to Bayer pattern sensors which leads to better image measurements, e.g., target detection (cf. Greiwe and Gehrke 2013b;Meißner et al 2017).…”

Section: Photogrammetric Measurements Using Uasmentioning

confidence: 99%

Gravitational deformation of ring-focus antennas for VGOS: first investigations at the Onsala twin telescopes project

Lösler

Haas

Eschelbach

et al. 2019

J Geod

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The receiving properties of radio telescopes used in geodetic and astrometric very long baseline interferometry (VLBI) depend on the surface quality and stability of the main reflector. Deformations of the main reflector as well as changes in the sub-reflector position affect the geometrical ray path length significantly. The deformation pattern and its impact on the VLBI results of conventional radio telescopes have been studied by several research groups using holography, laser tracker, close-range photogrammetry and laser scanner methods. Signal path variations (SPV) of up to 1 cm were reported, which cause, when unaccounted for, systematic biases of the estimated vertical positions of the radio telescopes in the geodetic VLBI analysis and potentially even affect the estimated scale of derived global geodetic reference frames. As a result of the realization of the VLBI 2010 agenda, the geodetic VLBI network is currently extended by several new radio telescopes, which are of a more compact and stiffer design and are able to move faster than conventional radio telescopes. These new telescopes will form the backbone of the next generation geodetic VLBI system, often referred to as VGOS (VLBI Global Observing System). In this investigation, for the first time the deformation pattern of this new generation of radio telescopes for VGOS is studied. ONSA13NE, one of the Onsala twin telescopes at the Onsala Space Observatory, was observed in several elevation angles using close-range photogrammetry. In general, these methods require a crane for preparing the reflector as well as for the data collection. To reduce the observation time and the technical effort during the measurement process, an unmanned aircraft system (UAS) was used for the first time. Using this system, the measurement campaign per elevation angle took less than 30 min. The collected data were used to model the geometrical ray path and its variations. Depending on the distance from the optical axis, the ray path length varies in a range of about ± 1 mm. To combine the ray path variations, an illumination function was introduced as weighting function. The resulting total SPV is about − 0.5 mm. A simple elevation-dependent SPV model is presented that can easily be used and implemented in VLBI data analysis software packages to correct for gravitational deformation in VGOS radio telescopes. The uncertainty is almost 200 µm (2σ) and is derived by Monte Carlo simulations applied to the entire analysis process. Keywords Ring-focus paraboloid • Radio telescope • Antenna deformation • VLBI • VGOS • Signal path variation • SQP • Reverse engineering • Photogrammetry • Unmanned aircraft system B Michael Lösler

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Benchmarking the Optical Resolving Power of Uav Based Camera Systems

Cited by 6 publications

References 10 publications

Uav Cameras: Overview and Geometric Calibration Benchmark

Uav Cameras: Overview and Geometric Calibration Benchmark

Evaluating the Performance of Photogrammetric Products Using Fixed-Wing UAV Imagery over a Mixed Conifer–Broadleaf Forest: Comparison with Airborne Laser Scanning

Gravitational deformation of ring-focus antennas for VGOS: first investigations at the Onsala twin telescopes project

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