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Journal articles on the topic 'Helicopter surveying'
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Gumert, William R., and Durwood Phillips. "Advanced helicopter aerogravity surveying system." Leading Edge 19, no. 11 (November 2000): 1252–55. http://dx.doi.org/10.1190/1.1438518.
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Bowerman, Terry S., and Alan R. Wasner. "Helicopter Soil Surveying in Northeastern Nevada." Soil Horizons 26, no. 4 (1985): 25. http://dx.doi.org/10.2136/sh1985.4.0025.
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Elliott, Kyle H., Paul A. Smith, and Victoria H. Johnston. "Aerial Surveys Do Not Reliably Survey Boreal-nesting Shorebirds." Canadian Field-Naturalist 124, no. 2 (April 1, 2010): 145. http://dx.doi.org/10.22621/cfn.v124i2.1053.
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Aerial surveys have been used as a method for surveying boreal-nesting shorebirds, which breed in difficult-to-access terrain; however, the fraction of breeding birds observed from the air is unknown. We investigated rates of detection by conducting simultaneous air and ground surveys for shorebirds at three sites in the boreal forest of the Northwest Territories, Canada, in 2007. Helicopter surveys included both pond-based surveys where the helicopter flew around the perimeter of each wetland and transect-based surveys where observers recorded birds seen on line transects. Ground surveys involved intensive observation, territory mapping and nest searching in 5 km2 of plots over a period of 5-6 weeks. Shorebird densities observed from the helicopter were highest near large bodies of water. No shorebirds were observed over closed forest despite breeding densities on ground surveys being highest in closed forest. Detection rates were very low, varied among species and aerial survey types, and were inconsistent over time. Ground-based observations showed that the shorebirds often did not flush in response to the helicopter passing overhead. Owing to poor rates of detection, we conclude that helicopter surveys are not an appropriate method for surveying breeding shorebirds in boreal habitats, but may have some utility for monitoring birds' use of stop-over locations.
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LANGHAMMER, LISBETH, LASSE RABENSTEIN, LINO SCHMID, ANDREAS BAUDER, MELCHIOR GRAB, PHILIPP SCHAER, and HANSRUEDI MAURER. "Glacier bed surveying with helicopter-borne dual-polarization ground-penetrating radar." Journal of Glaciology 65, no. 249 (December 21, 2018): 123–35. http://dx.doi.org/10.1017/jog.2018.99.
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ABSTRACTTraditionally, helicopter-borne ground-penetrating radar (GPR) systems are operated with a single pair of bistatic dipole antennas to measure the thickness of glaciers. We demonstrate numerically that the directivity of the radiation pattern of single airborne dipoles do not correspond to an ideal full-space solution if the antennas are employed at typical flight heights. These directionality effects can degrade the quality of the subsurface images significantly, when the GPR antennas are orientated unfavorably. Since an adjustment of the antenna orientation is impractical during flight, we have developed a novel dual-polarization helicopter-borne GPR system consisting of two orthogonal pairs of commercial antennas in broadside configuration. To overcome the image quality deficits of the individual channels, we apply a pseudo-scalar approach in which we combine the data of both polarizations. Results of helicopter-borne GPR surveys on two alpine glaciers in Switzerland reveal more coherent bedrock reflections in the summed data compared with single dipole pair profiles. Generally, the dual-polarization setup is more suitable than a single antenna systems, because it is more versatile and less prone to directional effects caused by the placement of the dipole antennas in relation to undulating subsurface reflectors.
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Rutishauser, Anja, Hansruedi Maurer, and Andreas Bauder. "Helicopter-borne ground-penetrating radar investigations on temperate alpine glaciers: A comparison of different systems and their abilities for bedrock mapping." GEOPHYSICS 81, no. 1 (January 1, 2016): WA119—WA129. http://dx.doi.org/10.1190/geo2015-0144.1.
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On the basis of a large data set, comprising approximately 1200 km of profile lines acquired with different helicopter-borne ground-penetrating radar (GPR) systems over temperate glaciers in the western Swiss Alps, we have analyzed the possibilities and limitations of using helicopter-borne GPR surveying to map the ice-bedrock interface. We have considered data from three different acquisition systems including (1) a low-frequency pulsed system hanging below the helicopter (BGR), (2) a stepped frequency system hanging below the helicopter (Radar Systemtechnik GmbH [RST]), and (3) a commercial system mounted directly on the helicopter skids (Geophysical Survey Systems Incorporated [GSSI]). The systems showed considerable differences in their performance. The best results were achieved with the BGR system. On average, the RST and GSSI systems yielded comparable results, but we observed significant site-specific differences. A comparison with ground-based GPR data found that the quality of helicopter-borne data is inferior, but the compelling advantages of airborne surveying still make helicopter-borne data acquisition an attractive option. Statistical analyses concerning the bedrock detectability revealed not only large differences between the different acquisition systems but also between different regions within our investigation area. The percentage of bedrock reflections identified (with respect to the overall profile length within a particular region) varied from 11.7% to 68.9%. Obvious factors for missing the bedrock reflections included large bedrock depths and steeply dipping bedrock interfaces, but we also observed that internal features within the ice body may obscure bedrock reflections. In particular, we identified a conspicuous “internal reflection band” in many profiles acquired with the GSSI system. We attribute this feature to abrupt changes of the water content within the ice, but more research is required for a better understanding of the nature of this internal reflection band.
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Tuck, Loughlin E., Claire Samson, Jeremy Laliberté, and Michael Cunningham. "Magnetic interference mapping of four types of unmanned aircraft systems intended for aeromagnetic surveying." Geoscientific Instrumentation, Methods and Data Systems 10, no. 1 (May 19, 2021): 101–12. http://dx.doi.org/10.5194/gi-10-101-2021.
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Abstract. Magnetic interference source identification is a critical preparation step for magnetometer-mounted unmanned aircraft systems (UAS) used for high-sensitivity geomagnetic surveying. A magnetic field scanner was built for mapping the low-frequency interference that is produced by a UAS. It was used to compare four types of electric-powered UAS capable of carrying an alkali-vapour magnetometer: (1) a single-motor fixed-wing, (2) a single-rotor helicopter, (3) a quad-rotor helicopter, and (4) a hexa-rotor helicopter. The scanner's error was estimated by calculating the root-mean-square deviation of the background total magnetic intensity over the mapping duration; averaged values ranged between 3.1 and 7.4 nT. Each mapping was performed above the UAS with the motor(s) engaged and with the UAS facing in two orthogonal directions; peak interference intensities ranged between 21.4 and 574.2 nT. For each system, the interference is a combination of both ferromagnetic and electrical current sources. Major sources of interference were identified such as servo(s) and the cables carrying direct current between the motor battery and the electronic speed controller. Magnetic intensity profiles were measured at various motor current draws for each UAS, and a change in intensity was observed for currents as low as 1 A.
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Matsuoka, Masayoshi, Alan Chen, Surya P. N. Singh, Adam Coates, Andrew Y. Ng, and Sebastian Thrun. "Autonomous Helicopter Tracking and Localization Using a Self-surveying Camera Array." International Journal of Robotics Research 26, no. 2 (February 2007): 205–15. http://dx.doi.org/10.1177/0278364906074898.
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Smith, M. J., and C. I. H. Joy. "Preliminary Investigations into Developments in Using Helicopter Photography for Highway Surveying." Photogrammetric Record 15, no. 85 (April 1995): 77–84. http://dx.doi.org/10.1111/0031-868x.00008.
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Doll, W. E., J. E. Nyquist, L. P. Beard, and T. J. Gamey. "Airborne geophysical surveying for hazardous waste site characterization on the Oak Ridge Reservation, Tennessee." GEOPHYSICS 65, no. 5 (September 2000): 1372–87. http://dx.doi.org/10.1190/1.1444828.
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Airborne geophysical methods that were developed for mineral and petroleum exploration can, with some modification, be applied to environmental problems where large areas must be characterized. A helicopter survey that deployed magnetic, electromagnetic, and radiometric sensors carried out one of the first large‐scale airborne environmental surveys at a U.S. government facility at Oak Ridge, Tennessee in 1993–1994. The survey included testing of a new airborne electromagnetic system designed specifically for environmental applications and for controlled field tests of magnetic systems. Helicopter‐borne magnetic measurements were capable of discriminating groups of as few as ten metallic 208-liter (55-gallon) storage drums under representative field conditions. Magnetic and electromagnetic sensors were able to distinguish groups of metal‐filled waste disposal trenches within disposal sites, but were unable to resolve individual trenches. Electromagnetic data proved to be the most effective airborne technique for geological mapping in this portion of the Appalachian fold‐and‐thrust belt and for locating karst features. Radiometric measurements were useful both in geological mapping and in detecting zones of high radiation related to hazardous waste. The Oak Ridge survey proved valuable for quickly screening large areas and for locating anomalies for subsequent ground follow‐up. On‐board video was used to reduce the number of instances of ground follow‐up by allowing the visual screening of anomalous areas.
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Boyd, Graham, and Julian Vrbancich. "A New Helicopter Time Domain AEM System for Shallow Seawater Geophysical Surveying – Static Trials." ASEG Extended Abstracts 2007, no. 1 (December 1, 2007): 1. http://dx.doi.org/10.1071/aseg2007ab016.
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KAWASHIMA, Kazuhiko, Shigeki UNJOH, and Hiroyuki IIDA. "Practical application of surveying method of earthquake disaster conditions in its early stages by means of helicopter." Journal of the Japan society of photogrammetry and remote sensing 28, no. 4 (1989): 2–3. http://dx.doi.org/10.4287/jsprs.28.4_2.
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Eaton, Perry A., Robert G. Anderson, Steven V. Queen, Bruno Y. Nilsson, Eric Lauritsen, Colin T. Barnett, Mark Olm, and Steven Mitchell. "Helicopter time-domain electromagnetics — Newmont and the NEWTEM experience." GEOPHYSICS 78, no. 6 (November 1, 2013): W45—W56. http://dx.doi.org/10.1190/geo2012-0472.1.
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Over the past two decades, the use of time-domain electromagnetic (EM) surveying systems, designed for an airborne helicopter-based platform, has risen in popularity. One of the first of these systems was developed and has been operated by Newmont Mining Corporation. The original system (NEWTEM I) and its more capable successor (NEWTEM II) were created to help our company explore for different types of mineral deposits, primarily gold bearing, as well as to provide general geologic mapping information in parts of the world that are often very difficult or expensive to explore otherwise. The NEWTEM system has some characteristics that have proven to be advantageous in terms of safety, cost of operation, spatial resolution, and the ability to map effectively at both ends of the resistivity scale. Our approach to the acquisition, processing, and interpretation of airborne EM data is specific to this system and to the goals of our gold-focused exploration programs. Using what is most often a locally derived helicopter, we are able to carry out a survey of whatever size our exploration program dictates and on a schedule that meets our company’s needs. Results from NEWTEM surveys have been used to identify conductive and resistive targets but more importantly to advance our general understanding of an area’s potential to host mineralization of interest to this company. We intended to provide a brief written account of the NEWTEM story for the scientific and exploration communities, including information about its design and capabilities, as well as how we process this type of data. Hopefully, this documentation will serve to inspire future developers, explorers, geoscientists, and airborne EM enthusiasts.
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Podgorski, Joel E., Esben Auken, Cyril Schamper, Anders Vest Christiansen, Thomas Kalscheuer, and Alan G. Green. "Processing and inversion of commercial helicopter time-domain electromagnetic data for environmental assessments and geologic and hydrologic mapping." GEOPHYSICS 78, no. 4 (July 1, 2013): E149—E159. http://dx.doi.org/10.1190/geo2012-0452.1.
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Helicopter time-domain electromagnetic (HTEM) surveying has historically been used for mineral exploration, but over the past decade it has started to be used in environmental assessments and geologic and hydrologic mapping. Such surveying is a cost-effective means of rapidly acquiring densely spaced data over large regions. At the same time, the quality of HTEM data can suffer from various inaccuracies. We developed an effective strategy for processing and inverting a commercial HTEM data set affected by uncertainties and systematic errors. The delivered data included early time gates contaminated by transmitter currents, noise in late time gates, and amplitude shifts between adjacent flights that appeared as artificial lineations in maps of the data and horizontal slices extracted from inversion models. Multiple processing steps were required to address these issues. Contaminated early time gates and noisy late time gates were semiautomatically identified and eliminated on a record-by-record basis. Timing errors between the transmitter and receiver electronics and inaccuracies in absolute amplitudes were corrected after calibrating selected HTEM data against data simulated from accurate ground-based TEM measurements. After editing and calibration, application of a quasi-3D spatially constrained inversion scheme significantly reduced the artificial lineations. Residual lineations were effectively eliminated after incorporating the transmitter and receiver altitudes and line-to-line amplitude factors in the inversion process. The final inverted model was very different from that generated from the original data provided by the contractor. For example, the average resistivity of the thick surface layer decreased from [Formula: see text] to [Formula: see text], the depths to the layer boundaries were reduced by 15%–23%, and the artificial lineations were practically eliminated. Our processing and inversion strategy is entirely general, such that with minor system-specific modifications it could be applied to any HTEM data set, including those recorded many years ago.
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Døssing, Arne, Eduardo Lima Simoes da Silva, Guillaume Martelet, Thorkild Maack Rasmussen, Eric Gloaguen, Jacob Thejll Petersen, and Johannes Linde. "A High-Speed, Light-Weight Scalar Magnetometer Bird for km Scale UAV Magnetic Surveying: On Sensor Choice, Bird Design, and Quality of Output Data." Remote Sensing 13, no. 4 (February 11, 2021): 649. http://dx.doi.org/10.3390/rs13040649.
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Magnetic surveying is a widely used and cost-efficient remote sensing method for the detection of subsurface structures at all scales. Traditionally, magnetic surveying has been conducted as ground or airborne surveys, which are cheap and provide large-scale consistent data coverage, respectively. However, ground surveys are often incomplete and slow, whereas airborne surveys suffer from being inflexible, expensive and characterized by a reduced signal-to-noise ratio, due to increased sensor-to-source distance. With the rise of reliable and affordable survey-grade Unmanned Aerial Vehicles (UAVs), and the developments of light-weight magnetometers, the shortcomings of traditional magnetic surveying systems may be bypassed by a carefully designed UAV-borne magnetometer system. Here, we present a study on the development and testing of a light-weight scalar field UAV-integrated magnetometer bird system (the CMAGTRES-S100). The idea behind the CMAGTRES-S100 is the need for a high-speed and flexible system that is easily transported in the field without a car, deployable in most terrain and weather conditions, and provides high-quality scalar data in an operationally efficient manner and at ranges comparable to sub-regional scale helicopter-borne magnetic surveys. We discuss various steps in the development, including (i) choice of sensor based on sensor specifications and sensor stability tests, (ii) design considerations of the bird, (iii) operational efficiency and flexibility and (iv) output data quality. The current CMAGTRES-S100 system weighs ∼5.9 kg (including the UAV) and has an optimal surveying speed of 50 km/h. The system was tested along a complex coastal setting in Brittany, France, targeting mafic dykes and fault contacts with magnetite infill and magnetite nuggets (skarns). A 2.0 × 0.3 km area was mapped with a 10 m line-spacing by four sub-surveys (due to regulatory restrictions). The sub-surveys were completed in 3.5 h, including >2 h for remobilisation and the safety clearance of the area. A noise-level of ±0.02 nT was obtained and several of the key geological structures were mapped by the system.
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Shahbazi, M., G. Sohn, J. Théau, and P. Ménard. "UAV-BASED POINT CLOUD GENERATION FOR OPEN-PIT MINE MODELLING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1/W4 (August 26, 2015): 313–20. http://dx.doi.org/10.5194/isprsarchives-xl-1-w4-313-2015.
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Along with the advancement of unmanned aerial vehicles (UAVs), improvement of high-resolution cameras and development of vision-based mapping techniques, unmanned aerial imagery has become a matter of remarkable interest among researchers and industries. These images have the potential to provide data with unprecedented spatial and temporal resolution for three-dimensional (3D) modelling. In this paper, we present our theoretical and technical experiments regarding the development, implementation and evaluation of a UAV-based photogrammetric system for precise 3D modelling. This system was preliminarily evaluated for the application of gravel-pit surveying. The hardware of the system includes an electric powered helicopter, a 16-megapixels visible camera and inertial navigation system. The software of the system consists of the in-house programs built for sensor calibration, platform calibration, system integration and flight planning. It also includes the algorithms developed for structure from motion (SfM) computation including sparse matching, motion estimation, bundle adjustment and dense matching.
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Foley, Neil, Slawek Tulaczyk, Esben Auken, Cyril Schamper, Hilary Dugan, Jill Mikucki, Ross Virginia, and Peter Doran. "Helicopter-borne transient electromagnetics in high-latitude environments: An application in the McMurdo Dry Valleys, Antarctica." GEOPHYSICS 81, no. 1 (January 1, 2016): WA87—WA99. http://dx.doi.org/10.1190/geo2015-0186.1.
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The McMurdo Dry Valleys are a polar desert in coastal Antarctica, where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. Liquid water is found at the surface only in lakes and in the temporary streams that feed them. Past geophysical exploration has yielded ambiguous results regarding the presence of subsurface water. In 2011, we used a helicopter-borne, time-domain electromagnetic (TDEM) sensor to map resistivity in the subsurface across the Dry Valleys. The airborne electromagnetic (AEM) method excels at finding subsurface liquid water in polar deserts, where water remains liquid under cold conditions if it is sufficiently saline, and therefore electrically conductive. Over the course of 26 h of helicopter time, we covered large portions of the Dry Valleys and vastly increased our geophysical understanding of the subsurface, particularly with respect to water. Our data show extensive subsurface low-resistivity layers approximately 150–250 m below the surface and beneath higher resistivity layers. We interpret the low-resistivity layers as geologic materials containing freeze-concentrated or “cryoconcentrated” hyper saline brines lying beneath glaciers and frozen permafrost. These brines appeared to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional-hydrogeologic system, wherein solutes might be transported between surface reservoirs by ionic diffusion and subsurface flow. The presence of such brines underneath glaciers might have implications for glacier movement. Systems such as this, where brines exist beneath glacial ice and frozen permafrost, may exist elsewhere in coastal Antarctica; AEM resistivity is an ideal tool to find and survey them. Our application of TDEM demonstrates that in polar subsurface environments containing conductive brines, such a diffusive electromagnetic method is superior to radar surveying in terms of depth of penetration and ability to differentiate hydrogeologic conditions.
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Jones, John W., Gregory B. Desmond, Charles Henkle, and Robert Glover. "An approach to regional wetland digital elevation model development using a differential global positioning system and a custom-built helicopter-based surveying system." International Journal of Remote Sensing 33, no. 2 (October 28, 2011): 450–65. http://dx.doi.org/10.1080/01431161.2010.533212.
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Langhammer, Lisbeth, Lasse Rabenstein, Andreas Bauder, and Hansruedi Maurer. "Ground-penetrating radar antenna orientation effects on temperate mountain glaciers." GEOPHYSICS 82, no. 3 (May 1, 2017): H15—H24. http://dx.doi.org/10.1190/geo2016-0341.1.
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Ground-penetrating radar (GPR) surveys on glaciers are generally restricted to a single pair of bistatic dipole antennas orientated either parallel or perpendicular to the surveying direction. Extensive helicopter-borne and ground-based GPR investigations on the Glacier d’Otemma, Switzerland, demonstrated that the detectability of the ice-bedrock interface varies substantially with dipole orientation. We recorded several across and along profiles using two different commercial GPR systems operated with 15, 25, 50, and 70 MHz antennas. Dipole alignments parallel to the glacier flow generated considerably stronger and more coherent bedrock reflections compared with a perpendicular dipole setup. We observed the behavior for all the systems and antenna frequencies that we used. To help explain these findings, we performed 3D numerical modeling using the open source software gprMax. Simulations with 20 MHz transmitting and receiving dipoles indicated that the changes of the bedrock reflection amplitude are primarily governed by the bedrock topography. Scattering and intrinsic attenuation may also influence the amplitudes of the bedrock reflections, but these effects seem to be much less pronounced. Evidently, to increase the GPR bedrock reflection quality, dipole antennas should be orientated parallel to the glacier flow direction on a glacier confined to a valley. Because the directional dependence is a first-order effect, it is advisable to perform multicomponent surveys when the general shape of the bedrock topography is unknown. The multicomponent setup preferably consists of two sets of dipole antennas, each in broadside configuration and the sets being orthogonal to each other.
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Girod, Luc, Christopher Nuth, Andreas Kääb, Bernd Etzelmüller, and Jack Kohler. "Terrain changes from images acquired on opportunistic flights by SfM photogrammetry." Cryosphere 11, no. 2 (March 28, 2017): 827–40. http://dx.doi.org/10.5194/tc-11-827-2017.
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Abstract. Acquiring data to analyse change in topography is often a costly endeavour requiring either extensive, potentially risky, fieldwork and/or expensive equipment or commercial data. Bringing the cost down while keeping the precision and accuracy has been a focus in geoscience in recent years. Structure from motion (SfM) photogrammetric techniques are emerging as powerful tools for surveying, with modern algorithm and large computing power allowing for the production of accurate and detailed data from low-cost, informal surveys. The high spatial and temporal resolution permits the monitoring of geomorphological features undergoing relatively rapid change, such as glaciers, moraines, or landslides. We present a method that takes advantage of light-transport flights conducting other missions to opportunistically collect imagery for geomorphological analysis. We test and validate an approach in which we attach a consumer-grade camera and a simple code-based Global Navigation Satellite System (GNSS) receiver to a helicopter to collect data when the flight path covers an area of interest. Our method is based and builds upon Welty et al. (2013), showing the ability to link GNSS data to images without a complex physical or electronic link, even with imprecise camera clocks and irregular time lapses. As a proof of concept, we conducted two test surveys, in September 2014 and 2015, over the glacier Midtre Lovénbreen and its forefield, in northwestern Svalbard. We were able to derive elevation change estimates comparable to in situ mass balance stake measurements. The accuracy and precision of our DEMs allow detection and analysis of a number of processes in the proglacial area, including the presence of thermokarst and the evolution of water channels.
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Voumard, Jérémie, Marc-Henri Derron, Michel Jaboyedoff, Pierrick Bornemann, and Jean-Philippe Malet. "Pros and Cons of Structure for Motion Embarked on a Vehicle to Survey Slopes along Transportation Lines Using 3D Georeferenced and Coloured Point Clouds." Remote Sensing 10, no. 11 (November 3, 2018): 1732. http://dx.doi.org/10.3390/rs10111732.
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We discuss the different challenges, pros and cons of the fairly new Structure for Motion (SfM) embarked on a vehicle (SfM-EV) technique for slope surveys along transportation network tracks using action cameras embarked on standard moving vehicles. This low-cost technique generates georeferenced and coloured 3D point clouds without using any ground control points. Four action cameras, two of which had an integrated GNSS chip, were used to collect a series of pictures of tracksides at a rate of two images per second each. The SfM-EV results were compared with the results of seven other 3D survey techniques to evaluate the precision and accuracy of this technique, demonstrating the ability of this simple setting to generate 3D scenes. Different platforms for the cameras were tested, such as a bike, car, train, funicular, helicopter and so on. The SfM-EV technique was also tested on several study sites to highlight its strengths and weaknesses and obtain data, such as the density of points, equations of errors, overlap ratios and image resolution. The precision of the SfM-EV results was sufficient for detecting topographical changes close to the track for a volume of ~1 dm3 and the absolute positioning obtained with a low sky obstruction was approximately 5 m. The precision of SfM-EV was of a similar order to the other techniques, with an order of magnitude of a few centimetres. This approach possesses a low price-result quality ratio and is very simple to use. The possibility of using any type of vehicle for surveying is an advantage, especially for transportation track embankments.
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Vernes, Karl, Melissa Freeman, and Brad Nesbitt. "Estimating the density of free-ranging wild horses in rugged gorges using a photographic mark - recapture technique." Wildlife Research 36, no. 5 (2009): 361. http://dx.doi.org/10.1071/wr07126.
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Estimating the density of large, feral species such as wild horses at landscape scales can present a logistical hurdle for wildlife managers attempting to set density-based management targets. We undertook aerial surveys of wild horses by using a helicopter in Guy Fawkes River National Park in north-eastern New South Wales across 3 years to determine whether meaningful density estimates could be obtained efficiently by a mark–recapture technique based on recognition of individual horses. Horse groups photographed from the air on the first of two surveys conducted each year were ‘marked’ on the basis of a unique combination of colours and natural markings, and ‘recaptured’ if they were photographed and identified on the second survey. Population size was estimated with the program MARK using a range of population estimators; however, because horses appeared to be evading detection on the second survey of each year, we chose a final estimation model that accounted for detection shyness in the study species. In 2005, the density estimate was 3.8 horses per km2 (upper and lower 95% CL = 3.5–5.7 horses per km2). Following horse control in these catchments, the estimate in 2007 was 2.3 horses per km2 (upper and lower 95% CL = 2.1–3.4 horses per km2), and this change in density can be accounted for by the known number of horses removed from the survey area between survey periods. Overall, the technique proved useful for estimating densities of wild horses in deeply dissected gorge country where other estimation techniques (such as line transects) are not practical; however, low recapture rates in one of the years of the study shows that the technique may not always be applicable. Our technique should also be suitable for surveying other large mammals with broad ranges in open environments, provided recognition of individuals from unique marks is possible.
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Owens, E. H., J. W. Engles, S. Lehmann, H. A. Parker-Hall, P. D. Reimer, and J. Whitney. "M/V SELENDANG AYURESPONSE: SHORELINE SURVEYS AND DATA MANAGEMENT; TREATMENT RECOMMENDATIONS; AND THE COMPLETION INSPECTION PROCESS." International Oil Spill Conference Proceedings 2008, no. 1 (May 1, 2008): 1193–99. http://dx.doi.org/10.7901/2169-3358-2008-1-1193.
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ABSTRACT The grounding of a bulk carrier on Unalaska Island in the Aleutian Chain, Alaska, on 8 December 2004, resulted in a spill of fuel oil that affected approximately 800 km of coastline in a remote area. Initial tracking of the spill commenced at the first opportunity on 11 December using a fixed-wing aircraft to conduct low-altitude surveys during weather windows. Subsequent Shoreline Cleanup Assessment Technique (SCAT) surveys involved both boat- and helicopter-based interagency teams to document and characterize oiling conditions. Of the 763 km of shoreline surveyed 713 km had “No Observed Oil (NOO)”. Information obtained by the surveys was entered and managed in a data base that was accessible to all members of the spill response team. Several innovative approaches were developed to assist the shoreline cleanup endpoint decision and inspection processes. Where oil was observed that did not meet the defined treatment end points, a Shoreline Treatment Recommendation Transmittal (STRT) form was completed and submitted to the Unified Command (UC) spill management team. As part of the shoreline survey program, Operations personnel accompanied the two teams surveying outside of the “core” area to remove small amounts of oil. This was, in effect, a “clean as you go” and a “sign off as you go” strategy to obviate the need to employ separate sorties for initial survey, return for treatment, and a third return to inspect the completed cleanup in the segment and determine if endpoints were met. If the segment met the treatment end points or was cleaned to that standard, a Shoreline Inspection Report (SIR) was completed and signed in the field by the UC representatives on the SCAT team recommending to the UC that cleanup in that segment was not necessary or that cleanup be terminated. The completion inspection process involved the land managers, and landowners, comprised primarily of native tribes and corporations for the bulk of the affected areas, as well as Federal and Alaskan state agencies.
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Echelmeyer, K., and B. Kamb. "Measurement of Short Period Motion On A Fast Moving Glacier and Analysis of Data (Abstract)." Annals of Glaciology 8 (1986): 204. http://dx.doi.org/10.1017/s0260305500001555.
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The investigation of glacier motion over short time periods for relatively long duration and over large longitudinal extent can yield valuable insight into the dynamics of glacier surging, basal sliding, ice stream development, and calving mechanisms. In this paper, we discuss techniques for monitoring short term horizontal and vertical motion employed on the often highly-fractured surface of Variegated Glacier, Alaska, prior to its recent surge (1980—84) and on the fast-moving outlet glacier — ice stream system of Jakobshavns Glacier, Greenland. The short period measurements described here were made continuously over one to several months, and, in many cases, encompass seasonal and longer term fluctuations as well. The positions of a relatively large number of surface markers (15-35) were followed as functions of time. Application of standard terrestrial surveying techniques and modern microwave and UHF positioning methods to these short period studies are discussed. We then describe methods of reduction and analysis on the resulting large data sets, which may be treated as quasi-stationary time series. Examples of correlation with other glacier variables, such as basal water pressure, seismicity, and stream discharge are given and the propagation of movement events discussed. The meaning of the term ‘short period’ is relative to the size and mean velocity of an ice mass. On a small, fast-moving glacier, such as Variegated, close to the time of surge, speeds of 0.5 to 65 m/day allow accurate measurement of surface velocity, uplift, and strain over hourly time intervals. Motion studies over similar time periods may be accurately performed on lower Jakobshavns Glacier, where average speeds of 20 m/day are present. On the other hand, 50—70 km from terra firma on upper Jakobshavns Glacier, speeds are much reduced and stable control is difficult to establish. In a region such as this short period becomes daily to weekly, or even longer if absolute velocities are required. Several factors are critical in the planning and successful completion of comprehensive short period motion study with a minimum of manpower. Choice of instrument type, location of control, marker construction and size, placement of markers on a highly-crevassed surface, and accuracy requirements all require careful consideration and are described in detail in this paper. On Variegated and lower Jakobshavns Glaciers standard theodolites and electronic distance meters (EDM) were used to determine the horizontal and vertical position of a surface marker from either the glacier margin or from a moving control point, on the ice itself, whose location was simultaneously monitored. Mean flow azimuth and plunge were determined by complete surveys made daily or weekly. Shorter period surveys were often limited to the measurement of either distances only or angles only, depending on the component of motion along the line of measurement. Interpolation among these data sets for a given point yields accurate velocity, strain-rate, and vertical motion. The motion of a larger number of points could be determined from a few survey stations in this manner - for example, up to 30 markers were surveyed from 2 stations continuously over a three month period, covering a longitudinal distance of 15 km along the glacier. Markers, consisting of poles drilled into the surface, metal and plastic tetrahedron, cloth drapes and dye bombs, were emplaced on foot, when feasible. At other times, however, the highly-fractured surface of these fast moving glaciers required deployment from a hovering helicopter. Many of the markers were equipped with fixed retro-reflecting prisms to facilitate EDM measurement. Remote light systems on control points allowed surveying during periods of darkness (when, invariably, interesting events tended to occur). On upper Jakobshavns Glacier, markers were located using a microwave, or UHF, positioning system installed on board a helicopter. The decrease in accuracy of such measurements relative to standard methods required longer time periods between positioning, but, even at these lower frequencies, significant fluctuations were observed. Guidance capabilities of the positioning systems allowed rapid reoccupation of marker sites on the vast ice surface and also allowed rapid mapping of surface topography and terminus position, Results show several interesting features of glacier dynamics: large fluctuations in velocity over periods of hours to days, rapid and substantial uplift of the surface, and the subsequent propagation of these movement events and kinematic-type waves along the surface; large seasonal DC shifts in velocity and interesting development of marginal and medial shear zones. Digitization and time-series analysis of the resulting data sets allow identification of significant periods of oscillation in glacier motion and quantitative description of the propagation of high-frequency disturbances. Correlation with continuous records of other variables on Variegated Glacier, observed by various investigators from University of Alaska and Washington and Caltech, such as borehole water level, seismicity, stream discharge, and small-scale strain and tilt, enables the first detailed observational description of a surging glacier to be made, and a detailed comparison with theoretical ideas. A new amendment to Murphy’s Law regarding such short period motion studies is also presented.
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Echelmeyer, K., and B. Kamb. "Measurement of Short Period Motion On A Fast Moving Glacier and Analysis of Data (Abstract)." Annals of Glaciology 8 (1986): 204. http://dx.doi.org/10.3189/s0260305500001555.
Full textAbstract:
The investigation of glacier motion over short time periods for relatively long duration and over large longitudinal extent can yield valuable insight into the dynamics of glacier surging, basal sliding, ice stream development, and calving mechanisms. In this paper, we discuss techniques for monitoring short term horizontal and vertical motion employed on the often highly-fractured surface of Variegated Glacier, Alaska, prior to its recent surge (1980—84) and on the fast-moving outlet glacier — ice stream system of Jakobshavns Glacier, Greenland. The short period measurements described here were made continuously over one to several months, and, in many cases, encompass seasonal and longer term fluctuations as well. The positions of a relatively large number of surface markers (15-35) were followed as functions of time. Application of standard terrestrial surveying techniques and modern microwave and UHF positioning methods to these short period studies are discussed. We then describe methods of reduction and analysis on the resulting large data sets, which may be treated as quasi-stationary time series. Examples of correlation with other glacier variables, such as basal water pressure, seismicity, and stream discharge are given and the propagation of movement events discussed.The meaning of the term ‘short period’ is relative to the size and mean velocity of an ice mass. On a small, fast-moving glacier, such as Variegated, close to the time of surge, speeds of 0.5 to 65 m/day allow accurate measurement of surface velocity, uplift, and strain over hourly time intervals. Motion studies over similar time periods may be accurately performed on lower Jakobshavns Glacier, where average speeds of 20 m/day are present. On the other hand, 50—70 km from terra firma on upper Jakobshavns Glacier, speeds are much reduced and stable control is difficult to establish. In a region such as this short period becomes daily to weekly, or even longer if absolute velocities are required.Several factors are critical in the planning and successful completion of comprehensive short period motion study with a minimum of manpower. Choice of instrument type, location of control, marker construction and size, placement of markers on a highly-crevassed surface, and accuracy requirements all require careful consideration and are described in detail in this paper.On Variegated and lower Jakobshavns Glaciers standard theodolites and electronic distance meters (EDM) were used to determine the horizontal and vertical position of a surface marker from either the glacier margin or from a moving control point, on the ice itself, whose location was simultaneously monitored. Mean flow azimuth and plunge were determined by complete surveys made daily or weekly. Shorter period surveys were often limited to the measurement of either distances only or angles only, depending on the component of motion along the line of measurement. Interpolation among these data sets for a given point yields accurate velocity, strain-rate, and vertical motion. The motion of a larger number of points could be determined from a few survey stations in this manner - for example, up to 30 markers were surveyed from 2 stations continuously over a three month period, covering a longitudinal distance of 15 km along the glacier.Markers, consisting of poles drilled into the surface, metal and plastic tetrahedron, cloth drapes and dye bombs, were emplaced on foot, when feasible. At other times, however, the highly-fractured surface of these fast moving glaciers required deployment from a hovering helicopter. Many of the markers were equipped with fixed retro-reflecting prisms to facilitate EDM measurement. Remote light systems on control points allowed surveying during periods of darkness (when, invariably, interesting events tended to occur).On upper Jakobshavns Glacier, markers were located using a microwave, or UHF, positioning system installed on board a helicopter. The decrease in accuracy of such measurements relative to standard methods required longer time periods between positioning, but, even at these lower frequencies, significant fluctuations were observed. Guidance capabilities of the positioning systems allowed rapid reoccupation of marker sites on the vast ice surface and also allowed rapid mapping of surface topography and terminus position,Results show several interesting features of glacier dynamics: large fluctuations in velocity over periods of hours to days, rapid and substantial uplift of the surface, and the subsequent propagation of these movement events and kinematic-type waves along the surface; large seasonal DC shifts in velocity and interesting development of marginal and medial shear zones. Digitization and time-series analysis of the resulting data sets allow identification of significant periods of oscillation in glacier motion and quantitative description of the propagation of high-frequency disturbances. Correlation with continuous records of other variables on Variegated Glacier, observed by various investigators from University of Alaska and Washington and Caltech, such as borehole water level, seismicity, stream discharge, and small-scale strain and tilt, enables the first detailed observational description of a surging glacier to be made, and a detailed comparison with theoretical ideas.A new amendment to Murphy’s Law regarding such short period motion studies is also presented.
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Fraser, R. H., I. Olthof, M. Maloley, R. Fernandes, C. Prevost, and J. van der Sluijs. "UAV PHOTOGRAMMETRY FOR MAPPING AND MONITORING OF NORTHERN PERMAFROST LANDSCAPES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1/W4 (August 27, 2015): 361. http://dx.doi.org/10.5194/isprsarchives-xl-1-w4-361-2015.
Full textAbstract:
Northern environments are changing in response to recent climate warming, resource development, and natural disturbances. The Arctic climate has warmed by 2–3°C since the 1950’s, causing a range of cryospheric changes including declines in sea ice extent, snow cover duration, and glacier mass, and warming permafrost. The terrestrial Arctic has also undergone significant temperature-driven changes in the form of increased thermokarst, larger tundra fires, and enhanced shrub growth. Monitoring these changes to inform land managers and decision makers is challenging due to the vast spatial extents involved and difficult access. <br><br> Environmental monitoring in Canada’s North is often based on local-scale measurements derived from aerial reconnaissance and photography, and ecological, hydrologic, and geologic sampling and surveying. Satellite remote sensing can provide a complementary tool for more spatially comprehensive monitoring but at coarser spatial resolutions. Satellite remote sensing has been used to map Arctic landscape changes related to vegetation productivity, lake expansion and drainage, glacier retreat, thermokarst, and wildfire activity. However, a current limitation with existing satellite-based techniques is the measurement gap between field measurements and high resolution satellite imagery. Bridging this gap is important for scaling up field measurements to landscape levels, and validating and calibrating satellite-based analyses. This gap can be filled to a certain extent using helicopter or fixed-wing aerial surveys, but at a cost that is often prohibitive. <br><br> Unmanned aerial vehicle (UAV) technology has only recently progressed to the point where it can provide an inexpensive and efficient means of capturing imagery at this middle scale of measurement with detail that is adequate to interpret Arctic vegetation (i.e. 1–5 cm) and coverage that can be directly related to satellite imagery (1–10 km<sup>2</sup>). Unlike satellite measurements, UAVs permit frequent surveys (e.g. for monitoring vegetation phenology, fires, and hydrology), are not constrained by repeat cycle or cloud cover, can be rapidly deployed following a significant event, and are better suited than manned aircraft for mapping small areas. UAVs are becoming more common for agriculture, law enforcement, and marketing, but their use in the Arctic is still rare and represents untapped technology for northern mapping, monitoring, and environmental research. <br><br> We are conducting surveys over a range of sensitive or changing northern landscapes using a variety of UAV multicopter platforms and small sensors. Survey targets include retrogressive thaw slumps, tundra shrub vegetation, recently burned vegetation, road infrastructure, and snow. Working with scientific partners involved in northern monitoring programs (NWT CIMP, CHARS, NASA ABOVE, NRCan-GSC) we are investigating the advantages, challenges, and best practices for acquiring high resolution imagery from multicopters to create detailed orthomosaics and co-registered 3D terrain models. Colour and multispectral orthomosaics are being integrated with field measurements and satellite imagery to conduct spatial scaling of environmental parameters. Highly detailed digital terrain models derived using structure from motion (SfM) photogrammetry are being applied to measure thaw slump morphology and change, snow depth, tundra vegetation structure, and surface condition of road infrastructure. <br><br> These surveys and monitoring applications demonstrate that UAV-based photogrammetry is poised to make a rapid contribution to a wide range of northern monitoring and research applications.
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Suzuki, Satoshi, and Kenzo Nonami. "Special Issue on Novel Technology of Autonomous Drone." Journal of Robotics and Mechatronics 33, no. 2 (April 20, 2021): 195. http://dx.doi.org/10.20965/jrm.2021.p0195.
Full textAbstract:
In the past three years, there has been rapid progress in the use of drones in society. Drones, which were previously used only experimentally in various industrial fields, are now being used in earnest in everyday operations. Drones are becoming indispensable tools in several industrial fields, such as surveying, inspection, and agriculture. At the same time, there has also been dramatic progress in autonomous drone technology. With the advancement of image processing, simultaneous localization and mapping (SLAM), and artificial intelligence technologies, many intelligent drones that apply these technologies are being researched. At the same time, our knowledge of multi-rotor helicopters, the main type of drones, has continued to deepen. As the strengths and weaknesses of multi-rotor helicopters have gradually become clearer, drones with alternate structures, such as flapping-wing drones, have come to attract renewed attention. In addition, the range of applications for drones, including passenger drones, has expanded greatly, and research on unprecedented drone operations, as well as research on systems and controls to ensure operational safety, is actively being conducted. This special issue contains the latest review, research papers, and development reports on autonomous drones classified as follows from the abovementioned perspectives. · Research on drone airframes and structures · Research on drone navigation and recognition with a focus on image processing · Research on advanced drone controls · Research and development of drone applications We hope that the readers will actively promote the use of drones in their own research and work, based on the information obtained from this special issue.
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Liu, Lihua, Jutao Li, Ling Huang, Xiaojun Liu, and Guangyou Fang. "Double Clamping Current Inverter with Adjustable Turn-off Time for Bucking Coil Helicopter Transient Electromagnetic Surveying." IEEE Transactions on Industrial Electronics, 2020, 1. http://dx.doi.org/10.1109/tie.2020.2987280.
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D. Damaske. "Merging aeromagnetic data collected at different levels: the GEOMAUD survey." Annals of Geophysics 42, no. 2 (April 18, 1999). http://dx.doi.org/10.4401/ag-3710.
Full textAbstract:
As part of the German GEOMAUD-expedition an aeromagnetic survey was carried out in Central Queen Maud Land. The helicopter-borne survey was designed in a conventional form of a regional survey with a spacing of profile-lines of 4.4 km. Due to terrain considerations - surveying from the coast across the mountain ranges to the high altitudes of the polar plateau - the survey was split into two sections flown at different constant levels. Over the coastal part survey elevation was 570 m (above sea level) while for the mountain section 2845 m was chosen. Both survey parts were processed separately. The low level section was upward continued before merging with the high level section. Though this leads to a homogeneous magnetic anomaly map, in some applications it may be more advantageous to present the anomalies of the magnetic field in original survey levels as a simple combined map because small scale features are preserved and can be used in recognizing magnetic units and patterns for geological/geophysical interpretation.
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Ferreira, Sam M., Cathy Greaver, and Chenay Simms. "Elephant population growth in Kruger National Park, South Africa, under a landscape management approach." Koedoe 59, no. 1 (August 25, 2017). http://dx.doi.org/10.4102/koedoe.v59i1.1427.
Full textAbstract:
South African National Parks (SANParks) manage landscapes rather than numbers of elephants (Loxodonta africana) to mitigate the effects that elephants may have on biodiversity, tourism and stakeholder conservation values associated with protected areas. This management philosophy imposes spatial variability of critical resources on elephants. Restoration of such ecological processes through less intensive management predicts a reduction in population growth rates from the eras of intensive management. We collated aerial survey data since 1995 and conducted an aerial total count using a helicopter observation platform during 2015. A minimum of 17 086 elephants were resident in the Kruger National Park (KNP) in 2015, growing at 4.2% per annum over the last generation of elephants (i.e. 12 years), compared to 6.5% annual population growth noted during the intensive management era ending in 1994. This may come from responses of elephants to density and environmental factors manifested through reduced birth rates and increased mortality rates. Authorities should continue to evaluate the demographic responses of elephants to landscape scale interventions directed at restoring the limitation of spatial variance in resource distribution on elephant spatiotemporal dynamics and the consequences that may have for other conservation values.Conservation implications: Conservation managers should continue with surveying elephants in a way that allows the extraction of key variables. Such variables should focus on measures that reflect on how theory predicts elephants should respond to management interventions.