<p><strong>Abstract.</strong> This paper presents a laboratory approach for geometric calibration of airborne camera systems. The setup uses an incoming laser beam, which is split by Diffractive Optical Elements (DOE) into a number of beams with precisely-known propagation directions. Each point of the diffraction pattern represents a point at infinity and is invariant against translation. A single image is sufficient to allow a complete camera calibration in accordance with classical camera calibration methods using the pinhole camera model and a distortion model. The presented method is time saving, since complex bundle adjustment procedures with several images are not necessary. It is well suited for the use with frame camera systems, but it works in principle also for pushbroom scanners. In order to prove the reliability, a conventional test field calibration is compared against the presented approach, showing that all estimated camera parameters are just insignificantly different. Furthermore a test flight over the Zeche Zollern reference target has been conducted. The aerotriangulation results shows that calibrating an airborne camera system with DOE is a feasible solution.</p>

A significant increase in global urban population affects the efficiency of urban transportation systems. Remarkable urban growth rates are observed in developing or newly industrialized countries where researchers, planners, and authorities face scarcity of relevant official data or geo-data. In this study, we explore remote sensing and open geo-data as alternative sources to generate missing data for transportation models in urban planning and research. We propose a multi-modal approach capable of assessing three essential parameters of the urban spatial structure: buildings, land use, and intra-urban population distribution. Therefore, we first create a very high-resolution (VHR) 3D city model for estimating the building floors. Second, we add detailed land-use information retrieved from OpenStreetMap (OSM). Third, we test and evaluate five experiments to estimate population at a single building level. In our experimental set-up for the mega-city of Santiago de Chile, we find that the multi-modal approach allows generating missing data for transportation independently from official data for any area across the globe. Beyond that, we find the high-level 3D city model is the most accurate for determining population on small scales, and thus evaluate that the integration of land use is an inevitable step to obtain fine-scale intra-urban population distribution.

Abstract. The largest floating tongue of Greenland’s ice sheet, Nioghalvfjerdsbræ, has been relatively stable with respect to areal retreat until 2022. Draining more than 6 % of the ice sheet, a disintegration of Nioghalvfjerdsbræ's floating tongue and subsequent acceleration due to loss in buttressing are likely to lead to sea level rise. Therefore, the stability of the floating tongue is a focus of this study. We employed a suite of observational methods to detect recent changes at the calving front. We found that the calving style has changed since 2016 at the southern part of the eastern calving front, from tongue-type calving to a crack evolution initiated at frontal ice rises reaching 5–7 km and progressing further upstream compared to 2010. The calving front area is further weakened by an area upstream of the main calving front that consists of open water and an ice mélange that has substantially expanded, leading to the formation of a narrow ice bridge. These geometric and mechanical changes may be a precursor of instability of the floating tongue. We complement our study by numerical ice flow simulations to estimate the impact of future ice-front retreat and complete ice shelf disintegration on the discharge of grounded ice. These idealized scenarios reveal that a loss of the south-eastern area of the ice shelf would lead to a 0.2 % increase in ice discharge at the grounding line, while a sudden collapse of the frontal area (46 % of the floating tongue area) will enhance the ice discharge by 5.1 % due to loss in buttressing. Eventually, a full collapse of the floating tongue increases the grounding line flux by 166 %.

Assessing the security status of maritime infrastructures is a key factor for maritime safety and security. Facilities such as ports and harbors are highly active traffic zones with many different agents and infrastructures present, like containers, trucks or vessels. Conveying security-related information in a concise and easily understandable format can support the decision-making process of stakeholders, such as port authorities, law enforcement agencies and emergency services. In this work, we propose a novel real-time 3D reconstruction framework for enhancing maritime situational awareness pictures by joining temporal 2D video data into a single consistent display. We introduce and verify a pipeline prototype for dynamic 3D reconstruction of maritime objects using a static observer and stereoscopic cameras on an GPU-accelerated embedded device. A simulated dataset of a harbor basin was created and used for real-time processing. Usage of a simulated setup allowed verification against synthetic ground-truth data. The presented pipeline runs entirely on a remote, low-power embedded system with $$\sim $$ ∼ 6 Hz. A Nvidia Jetson Xavier AGX module was used, featuring 512 CUDA-cores, 16 GB memory and an ARMv8 64-bit octa-core CPU.

Abstract. Many drones are used to obtain high resolution imagery. Subsequent 3D object point derivation from images of these systems is an established technique. While rotor-craft drones are often used to capture fine, detailed structures and objects in small-scale areas fixed-wing versions are commonly used to cover larger areas even far beyond line of sight. Usually, these drones fly at much higher velocities during data acquisition and therefore the according sensor requirements are much higher.This paper presents the evaluation of a prototype camera system for fast flying fixed-wing drones. Focus of investigation is to find out if higher operating velocities, up to 100 km/h during image acquisition, has any influence on photogrammetric survey and image quality itself. It will be shown that images, obtained by the presented camera system and carrier, do not suffer from motion blur and that the overall survey accuracy is approximately 1/4 of ground sample distance.Survey accuracy analysis is carried out using standard photgrammetric procedures using signaled control- and checkpoints and verifying their conformity in image space and object space.Fundamentals of image quality will be introduced, as well asan approach to determine and evaluate motion smear of remote sensing senors (in theory and practical use case). Furthermore, it will be shown that the designed camera system mounted on a fixed-wing carrier does not suffer from motion smear.