Positioning in time and space: cost-effective exterior orientation for airborne archaeological photographs

Since manned, airborne aerial reconnaissance for archaeological purposes is often characterised by more-or-less random photographing of archaeological features on the Earth, the exact position and orientation of the camera during image acquisition becomes very important in an effective inventorying and interpretation workflow of these aerial photographs. Although the positioning is generally achieved by simultaneously logging the flight path or directly recording the camera's position with a GNSS receiver, this approach does not allow to record the necessary roll, pitch and yaw angles of the camera. The latter are essential elements for the complete exterior orientation of the camera, which allows – together with the inner orientation of the camera – to accurately define the portion of the Earth recorded in the photograph. This paper proposes a cost-effective, accurate and precise GNSS/IMU solution (image position: 2.5 m and orientation: 2°, both at 1σ) to record all essential exterior orientation parameters for the direct georeferencing of the images. After the introduction of the utilised hardware, this paper presents the developed software that allows recording and estimating these parameters. Furthermore, this direct georeferencing information can be embedded into the image's metadata. Subsequently, the first results of the estimation of the mounting calibration (i.e. the misalignment between the camera and GNSS/IMU coordinate frame) are provided. Furthermore, a comparison with a dedicated commercial photographic GNSS/IMU solution will prove the superiority of the introduced solution. Finally, an outlook on future tests and improvements finalises this article

Accuracy analysis of direct georeferenced UAV images utilising low-cost navigation sensors

Unmanned aerial vehicles (UAVs), also known as unmanned airborne systems (UAS) or remotely piloted airborne systems (RPAS), are an established platform for close range airborne photogrammetry. Compared to manned platforms, the acquisition of local remote sensing data by UAVs is a convenient and very flexible option. For the application in photogrammetry UAVs are typically equipped with an autopilot and a lightweight digital camera. The autopilot includes several navigation sensors, which might allow an automated waypoint flight and offer a systematic data acquisition of the object resp. scene of interest. Assuming a sufficient overlap between the captured images, the position (3 coordinates: x, y, z) and the orientation (3 angles: roll, pitch, yaw) of the images can be estimated within a bundle block adjustment. Subsequently, coordinates of observed points that appear in at least two images, can be determined by measuring their image coordinates or a dense surface model can be generated from all acquired images by automated image matching. For the bundle block adjustment approximate values of the position and the orientation of the images are needed. To gather this information, several methods exist. We introduce in this contribution one of them: the direct georeferencing of images by using the navigation sensors (mainly GNSS and INS) of a low-cost on-board autopilot. Beside automated flights, the autopilot offers the possibility to record the position and the orientation of the platform during the flight. These values don’t correspond directly to those of the images. To compute the position and the orientation of the images two requirements must be fulfilled. First the misalignment angles and the positional differences between the camera and the autopilot must be determined (mounting calibration). Second the synchronization between the camera and the autopilot has to be established. Due to the limited accuracy of the navigation sensors, a small number of ground control points should be used to improve the estimated values, especially to decrease the amount of systematic errors. For the bundle block adjustment the calibration of the camera and their temporal stability must be determined additionally. This contribution presents next to the theory a practical study on the accuracy analysis of direct georeferenced UAV imagery by low-cost navigation sensors. The analysis was carried out within the research project ARAP (automated (ortho)rectification of archaeological aerial photographs). The utilized UAS consists of the airplane “MAJA”, manufactured by “Bormatec” (length: 1.2 m, wingspan: 2.2 m) equipped with the autopilot “ArduPilot Mega 2.5”. For image acquisition the camera “Ricoh GR Digital IV” is utilised. The autopilot includes a GNSS receiver capable of DGPS (EGNOS), an inertial measurement system (INS), a barometer, and a magnetometer. In the study the achieved accuracies for the estimated position and orientation of the images are presented. The paper concludes with a summary of the remaining error sources and their possible corrections by applying further improvements on the utilised equipment and the direct georeferencing process

Automated archiving of archaeological aerial images

The main purpose of any aerial photo archive is to allow quick access to images based on content and location. Therefore, next to a description of technical parameters and depicted content, georeferencing of every image is of vital importance. This can be done either by identifying the main photographed object (georeferencing of the image content) or by mapping the center point and/or the outline of the image footprint. The paper proposes a new image archiving workflow. The new pipeline is based on the parameters that are logged by a commercial, but cost-effective GNSS/IMU solution and processed with in-house-developed software. Together, these components allow one to automatically geolocate and rectify the (oblique) aerial images (by a simple planar rectification using the exterior orientation parameters) and to retrieve their footprints with reasonable accuracy, which is automatically stored as a vector file. The data of three test flights were used to determine the accuracy of the device, which turned out to be better than 1° for roll and pitch (mean between 0.0 and 0.21 with a standard deviation of 0.17–0.46) and better than 2.5° for yaw angles (mean between 0.0 and −0.14 with a standard deviation of 0.58–0.94). This turned out to be sufficient to enable a fast and almost automatic GIS-based archiving of all of the imagery

Statistical performance analysis with dynamic workload using S-NET

Volkmar Wieser, Philip K. F. Hölzenspies, Michael Roßbory, and Raimund Kirner, 'Statistical performance analysis with dynamic workload using S-NET'. Paper presented at the Workshop on Feedback-Directed Compiler Optimization for Multi-Core Architectures. Paris, France 23-25 January 2012In this paper the ADVANCE approach for engineering con- current software systems with well-balanced hardware ef- ficiency is adressed using the stream processing language S-Net. To obtain the cost information in the concurrent system the metrics throughput, latency, and jitter are evalu- ated by analyzing generated synthetical data as well as using an industrial related application in the future. As fall-out an Eclipse plugin for S-Net has been developed to provide sup- port for syntax highlighting, content assistance, hover help, and more, for easier and faster development. The presented results of the current work are on the one hand an indicator for the status quo of the ADVANCE vision and on the other hand used to improve the applied statistical analysis tech- niques within ADVANCE. Like the ADVANCE project, this work is still under development, but further improvements and speedups are expected in the near future

Nanoparticle detection in an open-access silicon microcavity

We report on the detection of free nanoparticles in a micromachined, open-access Fabry-P\'erot microcavity. With a mirror separation of $130\,\mu$m, a radius of curvature of $1.3\,$mm, and a beam waist of $12\,\mu$m, the mode volume of our symmetric infrared cavity is smaller than $15\,$pL. The small beam waist, together with a finesse exceeding 34,000, enables the detection of nano-scale dielectric particles in high vacuum. This device allows monitoring of the motion of individual $150\,$nm radius silica nanospheres in real time. We observe strong coupling between the particles and the cavity field, a precondition for optomechanical control. We discuss the prospects for optical cooling and detection of dielectric particles smaller than $10\,$nm in radius and $1\times10^7\,$amu in mass.Comment: 4 pages, 3 figure

Total hip replacement in patients with history of illicit injecting drug use

Background: A history of illicit injecting drug use makes indication of total hip arthroplasty (THA) in patients with end stage hip osteoarthritis difficult, as the risk of infection with colonized strains is multiplied if the patient continues to inject or inhale illicit drugs. Methods: A retrospective survivorship analysis of a consecutive series of 27 THA in patients with a history of illicit drug use was performed. Follow-up evaluation consisted of (1) a WOMAC score, (2) a standardized interview including queries on drug habits and eventual additional medico-surgical treatments of the affected hip, (3) a clinical examination in order to complete a Harris Hip Score, (4) radiological examination and (5) blood tests (blood sedimentation rates and C-reactive protein). Defined endpoints were death, implant revised or awaiting revision for deep infection or any other reason and lost to follow-up or follow-up after at least 2years. Results: Overall, 5- and 10-year implant survival rates with failure for any reason were 61% (CI: 41;81) and 52.3% (CI: 29;76) and for septic reasons 70.6% (CI: 52;89) and 60.5% (CI: 36;85), respectively. Even if at the time of THA all patients and respective health care professionals confirmed abstinence of illicit injecting drug use, five patients reported occasional use. Declared abstinence of less than 1year before THA was associated with higher recurrence rates (p=0.001) and both with higher septic failure rates (p=0.023, p=0.061). Positive serology for human deficiency virus did not increase implant failure rates. Conclusion: We use this unacceptable high failure rate as evidence when counseling patients and their health care professionals about the appropriate treatment of osteoarthritis in patients with a history of illicit drug use. Furthermore, we support the request of hair analysis for drugs documenting abstinence of at least 1year before indicating TH

Rahmendokument zur Analyse der Kostenentwicklung in der obligatorischen Krankenpflegeversicherung

Die steigenden Kosten in der obligatorischen Krankenpflegeversicherung (OKP) sind eine grosse und zunehmende finanzielle Belastung für viele Haushalte. In der gesundheitspolitischen Diskussion werden eine Vielzahl von Kostentreibern genannt, fundierte Erkenntnisse zum Beitrag einzelner Kostentreiber fehlen aber weitgehend. Das vorliegende Rahmendokument soll aufzeigen, 1) welche Treiber für das Wachstum der Gesundheitskosten in der Schweiz verantwortlich sein könnten, 2) welcher Anteil des Wachstums auf demographische Faktoren zurückzuführen ist, 3) welche Erkenntnisse eine aktuelle Studie zum Wachstumsbeitrag einzelner Kostentreiber liefert und 4) welche zukünftigen Analysen zu einem besserem Verständnis der Kostentreiber in der OKP beitragen könnten. Grundsätzlich können sowohl steigende Preise wie steigende Mengen von Gesundheitsleistungen pro Kopf der Bevölkerung zu steigenden OKP-Kosten führen. Die meisten Preise werden im Rahmen von komplexen Tarifstrukturen zwischen Versicherern und Leistungserbringern ausgehandelt, wobei die Preise tendenziell den durchschnittlichen Kosten bei effizienter Produktion entsprechen sollten. Daneben spielen Bund und Kantone eine wichtige Rolle, da sie die Tarife genehmigen müssen und die Preise vieler Gesundheitsgüter direkt vom Bund festgelegt werden. Die Menge der in Anspruch genommenen Gesundheitsleistungen wird von einer Vielzahl von Faktoren bestimmt, wie der Demographie, der Gesundheit der Bevölkerung, dem Stand der Medizin, dem Einkommen, dem Zugang zu Gesundheitsleistungen und den (Fehl-) Anreizen für die Leistungserbringer, Patientinnen und Versicherten. Die neue Studie zum Wachstumsbeitrag einzelner Kostentreiber in der Schweiz basiert auf einer detaillierten Zerlegung der gesamten Gesundheitsausgaben nach Krankheiten, Leistungen, Alter und Geschlecht in den Jahren 2012 und 2017. Die wichtigsten Erkenntnisse zur Zunahme der Kosten pro Kopf sind: 1) Die Preise hatten keinen Einfluss, da sie tendenziell sogar gesunken sind. 2) Ein Drittel der Zunahme lässt sich durch die Alterung der Bevölkerung und die Zunahme von Erkrankungen erklären. 3) Die verbleibenden zwei Drittel der Zunahme sind auf eine Zunahme der Leistungen pro Erkrankten zurückzuführen. Zukünftige Analysen sollten vor allem untersuchen, welche Ursachen für die Zunahme der Leistungen pro Erkrankten verantwortlich sind. Es geht darum zu verstehen, wie gross der Beitrag des medizinischen Fortschritts ist, da dieser wesentlich zur Verbesserung der Gesundheit beitragen kann, und wie gross der Beitrag von eigentlich unnötigen Leistungen ist

Experimental loss of menisci, cartilage and subchondral bone gradually increases anteroposterior knee laxity

Purpose: Anteroposterior knee stability is a relevant factor for the decision-making process of various surgical procedures. In degenerative joints when the implantation of unicompartimental prostheses or corrective osteotomies of the limb are planned, the integrity of the anteroposterior stability with an intact ACL has been regarded as a necessary prerequisite. We hypothesise that joint degeneration, however, may influence the anteroposterior knee laxity. Therefore, we set out to test this hypothesis simulating a progressively ‘degenerated' joint in an experimental cadaveric setting. Methods: Twelve intact transfemorally resected Thiel-fixated cadaver knee joints were divided into 2 groups for manipulation in the medial or lateral compartment. In each knee, we performed (1) unilateral total meniscectomy; (2) simulation of advanced osteoarthritis, by unilateral total cartilage debridement; (3) simulation of a unilateral tibial impression fracture, by resection of 5mm of the tibial plateau; (4) transection of the ACL. The KT-1000 arthrometer was used to measure the extent of anteroposterior translation at 30° of knee flexion. Results: The mean value for tibial anteroposterior translation before intervention was 3.2mm (SD: ±0.8). The mean translation after each intervention was 4.6mm (SD: ±0.9; +44%; n.s.) after meniscectomy, 5.9mm (SD: ±1.5; +84%; P<0.05) after cartilage debridement, 8mm (SD: ±1.5; +150%; P<0.01) after bone debridement, and finally 9.7mm (SD: ±2.2; +203%; P<0.05) after resection of the ACL. There were no significant differences between the medial and lateral compartment. Conclusion: In absence of massive osteophytes or capsular shrinkage, rapid loss of meniscus, cartilage and particularly loss of subchondral bone may result in a massive increase in anteroposterior translation, mimicking a tear of the ACL. In such a situation, a false positive impression of a ligamentous injury may arise, and decision making is falsely directed away from totally or partially knee joint-preserving procedures. Therefore, in degenerate joints, clinical evaluation of anteroposterior stability should rather rely on the presence of a firm stop than an overall increased joint translatio