COMBINATION OF TERRESTRIAL LASERSCANNING, UAV AND CLOSE-RANGE PHOTOGRAMMETRY FOR 3D RECONSTRUCTION OF COMPLEX CHURCHES IN GEORGIA

In September 2018, photogrammetric images and terrestrial laser scans were carried out as part of a measurement campaign for the three-dimensional recording of several historic churches in Tbilisi (Georgia). The aim was the complete spatial reconstruction with a spatial resolution and accuracy of approx. 1cm under partly difficult external conditions, which required the use of different measurement techniques.The local measurement data were collected by two laser scanning campaigns (Leica BLK360 and Faro Focus 3D X330), two UAV flights and two terrestrial image sets. The photogrammetric point clouds were calculated with the SfM programs AgiSoft PhotoScan and RealityCapture taking into account the control points from the Faro laser scan. The mean residual errors from the registrations or photogrammetric evaluations are 4-12mm, depending on the selected software. The best completeness and quality of the resulting 3D model was achieved by using laserscan data and images simultaneously.</p

Mitigating systematic error in topographic models for geomorphic change detection: Accuracy, precision and considerations beyond off‐nadir imagery

Unmanned aerial vehicles (UAVs) and structure-from-motion photogrammetry enable detailed quantification of geomorphic change. However, rigorous precision-based change detection can be compromised by survey accuracy problems producing systematic topographic error (e.g. 'doming'), with error magnitudes greatly exceeding precision estimates. Here, we assess survey sensitivity to systematic error, directly correcting topographic data so that error magnitudes align more closely with precision estimates. By simulating conventional grid-style photogrammetric aerial surveys, we quantify the underlying relationships between survey accuracy, camera model parameters, camera inclination, tie point matching precision and topographic relief, and demonstrate a relative insensitivity to image overlap. We show that a current doming-mitigation strategy of using a gently inclined ( 0 center dot 3 m, representing accuracy issues an order of magnitude greater than precision-based error estimates. For higher-relief topography, and for nadir-imaging surveys of the lower-relief topography, systematic error was <0 center dot 09 m. Modelling and subtracting the systematic error directly from the topographic data successfully reduced error magnitudes to values consistent with twice the estimated precision. Thus, topographic correction can provide a more robust approach to uncertainty-based detection of event-scale geomorphic change than designing surveys with small off-nadir camera inclinations and, furthermore, can substantially reduce ground control requirements. (c) 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Lt

A comparison of drug transport in pulmonary absorption models: isolated perfused rat lungs, respiratory epithelial cell lines and primary cell culture

Purpose: To evaluate the ability of human airway epithelial cell layers and a simple rat isolated perfused lung (IPL) model to predict pulmonary drug absorption in rats in vivo. Method: The permeability of seven compounds selected to possess a range of lipophilicity was measured in two airway cell lines (Calu-3 and 16HBE14o-), in normal human bronchial epithelial (NHBE) cells and using a simple isolated perfused lungs (IPL) technique. Data from the cell layers and ex vivo lungs were compared to published absorption rates from rat lungs measured in vivo. Results: A strong relationship was observed between the logarithm of the in vivo absorption half-life and the absorption half-life in the IPL (r = 0.97; excluding formoterol). Good log-linear relationships were also found between the apparent first-order absorption rate in vivo and cell layer permeability with correlation coefficients of 0.92, 0.93, 0.91 in Calu-3, 16HBE14o- and NHBE cells, respectively. Conclusion: The simple IPL technique provided a good prediction of drug absorption from the lungs, making it a useful method for empirical screening of drug absorption in the lungs. Permeability measurements were similar in all the respiratory epithelial cell models evaluated, with Calu-3 having the advantage for routine permeability screening purposes of being readily availability, robust and easy to culture

INVESTIGATIONS ON THE QUALITY OF THE INTERIOR ORIENTATION AND ITS IMPACT IN OBJECT SPACE FOR UAV PHOTOGRAMMETRY

With respect to the usual processing chain in UAV photogrammetry the consideration of the camera’s influencing factors on the accessible accuracy level is of high interest. In most applications consumer cameras are used due to their light weight. They usually allow only for automatic zoom or restricted options in manual modes. The stability and long-term validity of the interior orientation parameters are open to question. Additionally, common aerial flights do not provide adequate images for self-calibration. Nonetheless, processing software include self-calibration based on EXIF information as a standard setting. The subsequent impact of the interior orientation parameters on the reconstruction in object space cannot be neglected. With respect to the suggested key issues different investigations on the quality of interior orientation and its impact in object space are addressed. On the one hand the investigations concentrate on the improvement in accuracy by applying pre-calibrated interior orientation parameters. On the other hand, image configurations are investigated that allow for an adequate self-calibration in UAV photogrammetry. The analyses on the interior orientation focus on the estimation quality of the interior orientation parameters by using volumetric test scenarios as well as planar pattern as they are commonly used in computer vision. This is done by using a Olympus Pen E-PM2 camera and a Canon G1X as representative system cameras. For the analysis of image configurations a simulation based approach is applied. The analyses include investigations on varying principal distance and principal point to evaluate the system’s stability

Linking errors in trend estimation for international surveys in education

peer reviewe

PRECISE LASER-BASED OPTICAL 3D MEASUREMENT OF WELDING SEAMS UNDER WATER

This paper deals with the development of a measuring procedure and an experimental set-up (stereo camera system in combination with a projecting line laser and a positioning unit) which are intended to detect the surface topography, particularly of welds, with high accuracy in underwater environments. The system concept makes provision for the fact that the device can be positioned in space and manipulated by hand. The development, optimization and testing of the system components for surface measurements as well as calibration and accuracy evaluations are the main objectives within this research project. Testing procedures and probes are constructed and evaluated to verify the results. First results will be shown, where the test objects are underwater. The development considers conditions for a future adaption to underwater use

Development of a stereo-laser-profile-system for the optical inspection of welding seams

This research project focuses on the development of an optical 3D measuring system that enables high accurate surface measurements of welding seams in order to detect impurities. The systems concept is based on a stereo camera system in conjunction with a projecting line laser. A second camera system is used as tracking or positioning component to obtain the position of the measuring systems in object space. The complete stereo laser-profile system will be used as a hand-held system. The development, optimization and testing of the system components (stereo camera system with projecting laser line and tracking component) for surface measurements as well as calibration and accuracy evaluations are the main objectives within this research project. Testing procedures and probes are constructed and evaluated to verify the results. The development considers conditions for a future adaption to underwater use