Accuracy aspects of stereo side-looking radar

The geometry of the radar stereo model and factors affecting visual radar stereo perception are reviewed. Limits to the vertical exaggeration factor of stereo radar are defined. Radar stereo model accuracies are analyzed with respect to coordinate errors caused by errors of radar sensor position and of range, and with respect to errors of coordinate differences, i.e., cross-track distances and height differences

Mapping of sea ice and measurement of its drift using aircraft synthetic aperture radar images

Side-looking radar images of Arctic sea ice were obtained as part of the Arctic Ice Dynamics Joint Experiment. Repetitive coverages of a test site in the Arctic were used to measure sea ice drift, employing single images and blocks of overlapping radar image strips; the images were used in conjunction with data from the aircraft inertial navigation and altimeter. Also, independently measured, accurate positions of a number of ground control points were available. Initial tests of the method were carried out with repeated coverages of a land area on the Alaska coast (Prudhoe). Absolute accuracies achieved were essentially limited by the accuracy of the inertial navigation data. Errors of drift measurements were found to be about ±2.5 km. Relative accuracy is higher; its limits are set by the radar image geometry and the definition of identical features in sequential images. The drift of adjacent ice features with respect to one another could be determined with errors of less than ±0.2 km

Structure from motion photogrammetry in forestry : a review

AbstractPurpose of ReviewThe adoption of Structure from Motion photogrammetry (SfM) is transforming the acquisition of three-dimensional (3D) remote sensing (RS) data in forestry. SfM photogrammetry enables surveys with little cost and technical expertise. We present the theoretical principles and practical considerations of this technology and show opportunities that SfM photogrammetry offers for forest practitioners and researchers.Recent FindingsOur examples of key research indicate the successful application of SfM photogrammetry in forestry, in an operational context and in research, delivering results that are comparable to LiDAR surveys. Reviewed studies have identified possibilities for the extraction of biophysical forest parameters from airborne and terrestrial SfM point clouds and derived 2D data in area-based approaches (ABA) and individual tree approaches. Additionally, increases in the spatial and spectral resolution of sensors available for SfM photogrammetry enable forest health assessment and monitoring. The presented research reveals that coherent 3D data and spectral information, as provided by the SfM workflow, promote opportunities to derive both structural and physiological attributes at the individual tree crown (ITC) as well as stand levels.SummaryWe highlight the potential of using unmanned aerial vehicles (UAVs) and consumer-grade cameras for terrestrial SfM-based surveys in forestry. Offering several spatial products from a single sensor, the SfM workflow enables foresters to collect their own fit-for-purpose RS data. With the broad availability of non-expert SfM software, we provide important practical considerations for the collection of quality input image data to enable successful photogrammetric surveys

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles ameliorate airway inflammation in a rat model of Chronic Obstructive Pulmonary Disease (COPD)

Background Chronic obstructive pulmonary disease (COPD) is an incurable and debilitating chronic disease characterized by progressive airflow limitation associated with abnormal levels of tissue inflammation. Therefore, stem cell-based approaches to tackle the condition are currently a focus of regenerative therapies for COPD. Extracellular vesicles (EVs) released by all cell types are crucially involved in paracrine, extracellular communication. Recent advances in the field suggest that stem cell-derived EVs possess a therapeutic potential which is comparable to the cells of their origin. Methods In this study, we assessed the potential anti-inflammatory effects of human umbilical cord mesenchymal stem cell (hUC-MSC)-derived EVs in a rat model of COPD. EVs were isolated from hUC-MSCs and characterized by the transmission electron microscope, western blotting, and nanoparticle tracking analysis. As a model of COPD, male Sprague-Dawley rats were exposed to cigarette smoke for up to 12 weeks, followed by transplantation of hUC-MSCs or application of hUC-MSC-derived EVs. Lung tissue was subjected to histological analysis using haematoxylin and eosin staining, Alcian blue-periodic acid-Schiff (AB-PAS) staining, and immunofluorescence staining. Gene expression in the lung tissue was assessed using microarray analysis. Statistical analyses were performed using GraphPad Prism 7 version 7.0 (GraphPad Software, USA). Student’s t test was used to compare between 2 groups. Comparison among more than 2 groups was done using one-way analysis of variance (ANOVA). Data presented as median ± standard deviation (SD). Results Both transplantation of hUC-MSCs and application of EVs resulted in a reduction of peribronchial and perivascular inflammation, alveolar septal thickening associated with mononuclear inflammation, and a decreased number of goblet cells. Moreover, hUC-MSCs and EVs ameliorated the loss of alveolar septa in the emphysematous lung of COPD rats and reduced the levels of NF-κB subunit p65 in the tissue. Subsequent microarray analysis revealed that both hUC-MSCs and EVs significantly regulate multiple pathways known to be associated with COPD. Conclusions In conclusion, we show that hUC-MSC-derived EVs effectively ameliorate by COPD-induced inflammation. Thus, EVs could serve as a new cell-free-based therapy for the treatment of COPD

2004, The Promise of Softcopy Photogrammetry Revisited

Digital large format aerial cameras can produce as many images as a user pleases, and yet the costs of the imagery do not increase, in fact they decrease. This is a vast difference from traditional film-based photogrammetry where minimizing the number of film images was a basic tenet of the discipline, since a project’s costs were directly proportional to the number of images needed to complete it. Minimizing costs no longer is defined by minimizing the number of images, but by minimizing the use of human labor hours. The entire economy of aerial imaging is changing with the transition to digital cameras and the full digital workflow. This will change the market’s behavior, both on the side of the end-users of photogrammetrically collected data as well as on the side of photogrammetric organizations. More images will be created per project, mapping repeat cycles will shorten, costs per project will decrease, new data products will emerge and the competitive cost structure in photogrammetric organizations will come under intense pressure. 1

Mobile mapping and computer vision for generation of 3D site models

ABSTRACT: Cultural heritage documentation has had spectacular successes in the preservation and restoration of sites destroyed by natural disasters or by war. These successes were largely based on photographic documentation, that were translated into construction information using manual methods to include all types of 3-dimensional cues, be this stereo, shadows, shading or the simple use of geometric knowledge about a building and combining this with a single image. Computer vision and direct shape measurements now add the option for an automated analysis of the imagery, thereby enabling a more complete assessment of sites than ever before. We review a series of projects and efforts to develop technologies, systems and applications with site models at accuracies in the range of at least ± 10 cm.

Parallel Matching of Synthetic Aperture Radar Images

. This paper presents an MPI-parallelized version of a matching algorithm for synthetic aperture radar (SAR) images. First the necessity for automated matching and the chosen algorithm are outlined briey, and the algorithmic structure and the applied parallelization strategy are then presented and discussed. Performance results on a Cray T3D and a PowerChallenge from SGI are given, showing unexpected dierences between these architectures. Performance analysis indicates a bottleneck in data I/O. 1 Introduction Producing an atlas of planet Venus based on data sensed by the Magellan probe is challenging due to the amount of data and the algorithms needed. More than 400 Gbyte of raw data must be processed, partially with specialized SAR algorithms that are very compute-intensive. NASA created the so-called Magellan Stereo Toolkit (MST) [1] as a collection of sequential algorithms which an individual data user could employ to process small subsets of the Magellan images. The mos..