Time-lapse Photos Research Articles

Observed meltwater-induced flexure and fracture at a doline on George VI Ice Shelf, Antarctica

Abstract Global Navigation Satellite System (GNSS) observations and ground-based timelapse photography obtained over the record-high 2019/2020 melt season are combined to characterise the flexure and fracture behaviour of a previously formed doline on George VI Ice Shelf, Antarctica. The GNSS timeseries shows a downward vertical displacement of the doline centre with respect to the doline rim of ~60 cm in response to loading from a central meltwater lake. The GNSS data also show a tens-of-days episode of rapid-onset, exponentially decaying horizontal displacement, where the horizontal distance between the doline rim and its centre increases by ~70 cm. We interpret this event as the initiation and/or widening of a fracture, aided by stress perturbations associated with meltwater loading in the doline basin. Viscous flexure modelling indicates that the meltwater loading generates tensile surface stresses exceeding 75 kPa. This, together with our timelapse photos of circular fractures around the doline, suggests the first such documentation of meltwater-loading-induced ‘ring fracture’ formation on an ice shelf, equivalent to the fracture type proposed as part of the chain-reaction lake drainage process involved in the 2002 breakup of the Larsen B Ice Shelf.

Pollination mechanism in Serapias with no pollinaria reconfiguration.

Orchidaceae, one of the most numerous families in the world's flora, have evolved various pollination strategies to favour cross-pollination, such as deceptive pollination and pollinarium reconfiguration. Among the terrestrial orchids of the Mediterranean, only species belonging to the genus Serapias show a strategy defined as shelter imitation. The floral elements form a tubular structure that insects use during their resting phases. The purpose of this article was to clarify the mechanisms that guarantee pollination with particular attention to the morphological interactions between orchids and pollinators and whether pollinaria reconfiguration is necessary in the promotion of cross-pollination in Serapias. Breeding system experiments and hand-pollination treatments indicated that Serapias was highly self-compatible, shows low value of natural fruit set and is pollinator limited. Time-lapse photos showed that the pollinarium had no refolding of the stipe or caudicle after its removal from the flower. The morphology of the flower determined the attack of the pollinarium on the occiput/vertex of insect. When the insect left the flower, the pollinarium was unable to encounter the stigma. When the insect made a second visit to another flower, the pollen masses of the first pollinarium ended up on the stigma and at the same time, the insect picked up a second pollinarium. Our observations and analyses suggested that morphological interactions between flower and pollinator are crucial to the success of pollination and to prevent self-pollination and thus that pollinarium reconfiguration is unnecessary in shelter deceptive orchids, such as Serapias species, for the promotion of cross-pollination. Serapias represent a case of interactions between plant and pollinator; the formation of the tubular shape of the flower is an essential preadaptation for the development of resting site mimicry originating exclusively in Serapias among Mediterranean orchids.

Water velocity preferences of two benthic fishes, spined loach Cobitis taenia and Northern golden loach Sabanejewia baltica: an experimental approach

Bottom-dwelling fishes with low swimming capacity burrow into soft substrates or occupy shelters, such as stones and vegetation, to reduce metabolic costs of holding their position in running waters. As a consequence, under natural conditions it can be difficult to examine the effect of water flow as the limiting factor of benthic fishes. The velocity (0, 10, 20, and 30 cm s−1) preferences of spined loach and Northern golden loach were examined experimentally in an isosceles, cross-shaped acrylic tank with five square chambers (side of 15 cm and 40 cm high). Fish could select freely between a sheltered place without water flow (two side cells) and with flow (three) cells. Fishes were observed for 40 min by taking time-lapse photos every 0.5 min, with the first 7.5 min (= 15 photos) treated as an acclimatization period. Each treatment was repeated 10 times with 65 photos analysed. The disparity between the proportion of fish observed in the active and passive areas of the tank was used as the preference or avoidance of the velocity treatment. Northern golden loach showed a random distribution between cells (no bias from a proportion of 3:2), only at a velocity 0 cm s−1 revealing strong preference for water flow 10 and 20 cm s−1 and avoidance of velocity of 30 cm s−1. Spined loach preferred a velocity of 10 cm s−1 and avoided velocities of 20 and 30 cm s−1. Surprisingly fish were not randomly distributed at a velocity of 0 cm s−1, at which they were more frequently found in passive cells than active ones. The results confirm that Northern golden loach is a rheophilic fish occurring only in running waters, whereas spined loach is an ubiquitous species distributed in slow-flowing as well as stagnant waters.

2D Photogrammetry as a Forwarder Load Measurement Technique

Research Highlights: In this study, we present the use of time-lapse photos as a way to estimate the height of the load on the forwarders. This approach, using nonprofessional outdoor cameras, is a cheap and time-effective solution for continuous load height measurements, and it offers at least the same accuracy as a gauge measurement. This method represents another approach to the automation of time studies in forestry. Background and Objectives: Time studies require information about the load on the forwarders. Until now, this information was obtained either by using a gauge measure, sampling of the load, or averaging the load from large area datasets. More accurate methods like laser scanning are costly and fragile. During time study preparations, we suggested a robust system of measuring the load height and tested it against the commonly used gauge measuring technique. Materials and Methods: Two cameras took pictures of the load; these photos were processed for camera lens distortion and rectified into the cartesian coordinate system, and the height of the load was calculated. These values were then tested against gauge measured values using paired t-test. Results: Straight line distance calculated from the images and the gauge-measured distance did not show a significant difference (p-value 0.9354). Calculated vertical distance was, however, significantly different from the calculated straight-line distance (p-value of 0.0015), suggesting possible bias of the gauge measured distance. The root mean square error (RMSE) of the rectification process was, on average, 0.42 cm. Conclusions: The proposed method was verified to correspond with the gauge measure method; however, our research raised the question of the gauge method reliability, as the taken measurements are not perfectly vertical, and for the correct load estimation, the vertical distance is needed. We, therefore, conclude that for this photogrammetry method, the vertical, rather than straight-line, distance should be used. The presented solution can be used for long-term data collection without interrupting the whole forwarding process for taking the load measurement. The longer data processing in office enables researchers to spend less time in the field taking hand measurements.

A photographic method for mapping angular locations of exterior solar obstructions

This paper describes a photographic method for characterizing angular locations of exterior obstructions that cause shadows on a window and an image format for storing and querying angular obstruction maps. Exterior shading obstructions typically include, building attachments like overhangs and fins, or site context like neighboring buildings and trees. The described method uses a calibrated fisheye camera in order to relate pixel coordinates to real world angles with the window as a reference plane.The proposed angular obstruction maps use a new image projection format with azimuth angle for the x-axis and profile angle for the y-axis. This image format offers the unique feature of preserving lines that are orthonormal to a vector perpendicular to a façade. The angular obstruction maps described in this paper are useful in automated control of building shading systems (motorized shades, electrochromic windows, etc) in response to shadows from building context.The photographic method for generating obstruction maps are validated using two methods. First, the sun location in time-lapse photos taken with the calibrated camera (with neutral density filter) is compared to sun position calculated with validated algorithms. Second, time-lapse photos are used to compare real-world sunshine on a window to what is predicted by the photo generated obstruction map. The validations demonstrate that the photographicall generated obstruction maps are accurate to less than 1 degree.

Abyssal Deposit‐Feeding Rates Consistent with the Metabolic Theory of Ecology

The metabolic theory of ecology (MTE) posits that metabolic rate controls ecological processes. Metabolic rate is a function of organism body mass. We tested a fundamental assumption of MTE, whether resource uptake scales to metabolism, using a temperature-adjusted model of ingestion for aquatic deposit feeders, and deposit-feeding rates of abyssal invertebrates estimated from time-lapse photos. Ingestion was significantly related to body mass, with a mass-scaling coefficient near the MTE-predicted value. Our results suggest that after temperature correction, all marine invertebrates might be summarized into a single mass-scaled ingestion rate, and provide insight into the potential mechanism for this assumption. This photograph illustrates the article “Abyssal deposit-feeding rates consistent with the metabolic theory of ecology” by Jennifer M. Durden, Brian J. Bett, Christine L. Huffard, Henry A. Ruhl, and Kenneth L. Smith published in Ecology. https://doi.org/10.1002/ecy.2564

Tracking icebergs with time-lapse photography and sparse optical flow, LeConte Bay, Alaska, 2016–2017

ABSTRACTWe present a workflow to track icebergs in proglacial fjords using oblique time-lapse photos and the Lucas-Kanade optical flow algorithm. We employ the workflow at LeConte Bay, Alaska, where we ran five time-lapse cameras between April 2016 and September 2017, capturing more than 400 000 photos at frame rates of 0.5–4.0 min−1. Hourly to daily average velocity fields in map coordinates illustrate dynamic currents in the bay, with dominant downfjord velocities (exceeding 0.5 m s−1 intermittently) and several eddies. Comparisons with simultaneous Acoustic Doppler Current Profiler (ADCP) measurements yield best agreement for the uppermost ADCP levels (~ 12 m and above), in line with prevalent small icebergs that trace near-surface currents. Tracking results from multiple cameras compare favorably, although cameras with lower frame rates (0.5 min−1) tend to underestimate high flow speeds. Tests to determine requisite temporal and spatial image resolution confirm the importance of high image frame rates, while spatial resolution is of secondary importance. Application of our procedure to other fjords will be successful if iceberg concentrations are high enough and if the camera frame rates are sufficiently rapid (at least 1 min−1 for conditions similar to LeConte Bay).

Direct field observations of massive bedload and debris-flow depositions in open check dams

Sediment detention basins, also called SABO dams, are key facilities in flood protection systems of mountain catchments, specifically in torrents prone to massive bedload transport or debris flows. A better understanding of the processes generating sediment trapping is required to optimize their functioning. Two monitoring stations have been implemented in the French Alps on two torrents: the Manival (Saint-Nazaire-Les-Eymes) and the Claret (Saint-Julien-Mont-Denis). Time-lapse photos show an event depositing 10,000 m3of debris flow in a basin in less than six minutes and several events partially filling the other basin with gravel, impairing its capacity to store debris flows later. After a presentation of the catchments, this paper qualitatively analyzes the dynamics of the depositions. It highlights and stresses the consistency and differences between bedload and debris-flow deposition. Overall, despite clear differences of geomorphic activity, deposits tend to fill the trap basins just enough to enable the sediment transport continuity reestablishment through the basin. The open check dams thus play a role only provided that this continuity precondition is completed. These observations enhance our comprehension of massive sediment trapping in torrents and our capacity to better adjust trap maintenance and design to the objective sought in each site.

Calving Behavior at Rink Isbræ, West Greenland, from Time-Lapse Photos

ABSTRACTThis study presents detailed observations of calving behavior variability from daily oblique photographs acquired over a five-year period (2007–2011) covering the terminus of Rink Isbræ, a major West Greenland outlet glacier. The evidence suggests that calving at Rink is characterized by two styles with distinct temporal and spatial footprints. The first style is characterized by frequent small magnitude events, which show clear seasonal variability with a marked increase in frequency immediately following ice mélange breakup and a peak in July. The second style is characterized by the sporadic detachment of kilometer-sized tabular icebergs with no clear seasonal signal. We suggest that two sets of mechanisms control calving variability at this location, namely (1) melt-driven processes enhancing submarine undercutting and (2) mechanically driven buoyant flexure. The presence of sea ice and/or ice mélange in the fjord presents an additional factor limiting calving in the winter.

Integration of space-borne and air-borne data in monitoring river ice processes in the Slave River, Canada

River ice plays an important role in the physical, biological, and human systems in northern regions. Due to the large extent and poor accessibility of many river systems, remote sensing techniques are a potential tool for collecting information and analyzing characteristics of river ice covers. Optical data with high temporal resolution (e.g. MODIS products) are suitable for monitoring river ice phenology and mapping river ice cover extent, while radar data (e.g. RADARSAT-2 imagery) offer an optimal approach to characterizing river ice thickness, ice types and seasonal changes of ice-cover characteristics. An integrated automated approach, utilizing remotely sensed data from both active and passive sensors, was developed and applied to characterize river ice processes along the Slave River, Northwest Territories, Canada. The results show that the analysis of MODIS band 2 (841–876 nm) time series can detect the date of river ice freeze onset (FO) and water clear of ice (WCI) with a deviation of up to 12 days and 3 days, respectively. The rate of river ice breakup is much faster than the rate of river freeze-up. The profiles of MODIS band 2 reflectance data along the river, however, showed insignificant differences between different breakup stages and ice types, making it challenging to map breakup ice types. In this case, RADARSAT-2 imagery can be used successfully to characterize and map four classes of water and ice covers during the breakup period, including intact ice, smooth rubble ice, rough rubble ice and open water. In association with hydrometeorological parameters, the thermal deterioration of the ice cover during breakup appears to be the primary breakup event in the Slave River. The results obtained from the analysis of MODIS and RADARSAT-2 data were compared with ground measurements of weather, flow and ice conditions (2000–2015), time-lapse photos and aerial surveys (2013–2015) along the Slave River, and show strong agreement.

Beach carrying capacity and protected areas: management issues in Arrábida Natural Park, Portugal

ABSTRACT Pereira da Silva, C.; Nogueira Mendes, R..; Moutinho, G.; Mota, V. and Fonseca, C., 2016. Beach carrying capacity and protected areas: management issues in Arrabida Natural Park, Portugal. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 680–684. Coconut Creek (Florida), ISSN 0749-0208. Arrabida Natural Park (Portugal) comprises beaches with high natural and scenic values under huge demand during peak season. Understanding patterns of beach use and the perceptions of users is essential for carrying capacity management. This paper discusses the use intensity and dynamic in two beaches, using data from onsite counting, time-lapse photos and a traffic counter. Users' perceptions regarding general aspects of the beaches and perceived crowding obtained through questionnaires are also presented. The number of users recorded in this study never r...

Use of time-lapse photography and digital image analysis to estimate breeding success of a cliff-nesting seabird

Development of new methods for obtaining basic demographic data from difficult-to-access breeding colonies and easily disturbed species is an important challenge in studies of seabirds. We describe a method that can generate data concerning annual breeding success of cliff-nesting seabirds or other colonial birds with open nests. Our method requires only a single visit to a colony every second or third year, and is based on the use of automated time-lapse photography. To test our method, we used time-lapse photos to examine the breeding success of Thick-billed Murres (Uria lomvia) in two breeding colonies in Greenland during the years 2011, 2012, and 2014. Based on the analysis of time-lapse photos, we found that hatching success during the 3 yr of our study ranged from 60% to 81%, fledging success from 89% to 95%, and breeding success from 53% to 74% (Table 1). Use of digital image analysis made it possible to differentiate between breeding and non-breeding birds and determine if and when breeding attempts failed or succeeded. The key to making our method a realistic long-term monitoring technique is the use of an automated, formal image analysis to process the thousands of photos from the time-lapse cameras and, more specifically, to reduce a large number of photos to a manageable number. Using our method, we needed 12–22 h per study plot, depending on the number of breeding sites per plot (range = 47–127) and whether it was the first or the second time the plot was analyzed, to obtain our estimates of hatching, fledging, and breeding success. This included time for data preparation, image analyses, visual inspections, and summarizing data in a spreadsheet. We found that our estimates of breeding success were comparable to those obtained by direct observation in the field. An important aspect of using time-lapse technology is to foresee potential reasons why time-lapse cameras might stop taking pictures, for example, equipment failure (camera, timer, or battery) or interference by visitors (e.g., vandalism or theft). As such, thorough testing of time-lapse systems and selecting camera locations less likely to be disturbed are most important. We believe that use of time-lapse photography in combination with digital image analysis to estimate breeding success can be useful for determining the breeding success of other cliff-nesting seabirds and, more generally, other birds that breed in colonies, especially those located in remote areas and where direct observation may disturb birds.

Why older adults spend time sedentary and break their sedentary behaviour: a mixed methods approach using life-logging equipment

Event Abstract Back to Event Why older adults spend time sedentary and break their sedentary behaviour: a mixed methods approach using life-logging equipment Manon L. Dontje1*, Calum Leask1, Juliet Harvey1, Dawn Skelton1 and Sebastien Chastin1 1 Glasgow Caledonian University, United Kingdom Background Older adults spend a large part of the day being sedentary, but several national and international health guidelines explicitly recommend that older adults should reduce their sedentary time and break prolonged periods of sitting to promote healthy ageing and well-being. In order to refine the guidelines and develop effective interventions, it is crucial to identify when, why and how older adults are most likely to be able to change their sitting habits. Aim The aim of this study was to utilise life-logging equipment (objective activity monitor and camera) to understand reasons for older people to remain sedentary and to break periods of prolonged sitting. Methods In this mixed-methods study, 30 older adults (mean (±SD) age 74.0±5.3 years) were asked to recollect their believed reasons for (breaking) sedentary behaviour. In addition, they were presented with a personal storyboard with objective records (1 day activity monitor [activPAL] and time-lapse camera images [ViconRevue]) of their daily behaviour and asked, during a semi-structured interview, to give their individual interpretation of their objectively measured sedentary behaviour and explain their actual reasons for (breaking) sedentary behaviour. The interview transcriptions were analysed using inductive thematic analysis. Results The most frequent reasons that people believed kept them sedentary were television/radio (48.3%), fatigue (34.5%) and health status (31.0%). The factors most often mentioned as actual reasons were eating/drinking (96.6%), television/radio (89.7%) and reading/crosswords (75.9%). Domestic chores (55.2%), walking (37.9%) and socialising (20.7%) were most often mentioned as reasons that people believed made them break their sedentary behaviour. The factors that were most often mentioned as actual reasons were domestic chores (86.2%), food/tea preparation (82.8%), and performing simple tasks (75.9%). Conclusions It can be concluded that a mixed methods approach, by combining objective data of an activity monitor with contextual information from time-lapse photos and subjective information from people regarding their own behaviour, is an useful method to provide indepth information about (breaking) sedentary behaviour in older adults. The results of this study showed that there is a difference in what older adults believe that are reasons for them to remain sedentary or break their sedentary time and what their actual reasons are. A personal story board based on objective measurements of sedentary behaviour can be a useful method to raise awareness and find individual and tailored ways to reduce sedentary behaviour and to increase the number of breaks in sedentary behaviour without much interference in daily routine. Acknowledgements N/A References N/A Keywords: Sedentary behaviour, Life-logging, acceleromter, accelerometer, Time-lapse camera, Qualitative interview, mixed methods research, older adults Conference: 2nd Behaviour Change Conference: Digital Health and Wellbeing, London, United Kingdom, 24 Feb - 25 Feb, 2016. Presentation Type: Poster presentation Topic: Academic Citation: Dontje ML, Leask C, Harvey J, Skelton D and Chastin S (2016). Why older adults spend time sedentary and break their sedentary behaviour: a mixed methods approach using life-logging equipment. Front. Public Health. Conference Abstract: 2nd Behaviour Change Conference: Digital Health and Wellbeing. doi: 10.3389/conf.FPUBH.2016.01.00040 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Dec 2015; Published Online: 09 Jan 2016. * Correspondence: PhD. Manon L Dontje, Glasgow Caledonian University, Glasgow, United Kingdom, manon.dontje@gcu.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Manon L Dontje Calum Leask Juliet Harvey Dawn Skelton Sebastien Chastin Google Manon L Dontje Calum Leask Juliet Harvey Dawn Skelton Sebastien Chastin Google Scholar Manon L Dontje Calum Leask Juliet Harvey Dawn Skelton Sebastien Chastin PubMed Manon L Dontje Calum Leask Juliet Harvey Dawn Skelton Sebastien Chastin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Construction performance monitoring via still images, time-lapse photos, and video streams: Now, tomorrow, and the future

Timely and accurate monitoring of onsite construction operations can bring an immediate awareness on project specific issues. It provides practitioners with the information they need to easily and quickly make project control decisions. Despite their importance, the current practices are still time-consuming, costly, and prone to errors. To facilitate the process of collecting and analyzing performance data, researchers have focused on devising methods that can semi-automatically or automatically assess ongoing operations both at project level and operation level. A major line of work has particularly focused on developing computer vision techniques that can leverage still images, time-lapse photos and video streams for documenting the work in progress. To this end, this paper extensively reviews these state-of-the-art vision-based construction performance monitoring methods. Based on the level of information perceived and the types of output, these methods are mainly divided into two categories (namely project level: visual monitoring of civil infrastructure or building elements vs. operation level: visual monitoring of construction equipment and workers). The underlying formulations and assumptions used in these methods are discussed in detail. Finally the gaps in knowledge that need to be addressed in future research are identified.

Assessment of ice-dam collapse by time-lapse photos at the Perito Moreno glacier, Argentina

Abstract. This research provides a feasibility study on the implementation and performance assessment of time-lapse processing of a monoscopic image sequence, acquired by a calibrated camera in the Perito Moreno Glacier in Argentina. The glacier is located at 50°28'23" S, 73°02'10" W at the Parque Nacional Los Glaciares, South Patagonia Icefield, Santa Cruz and has experienced minor fluctuations and unusual behavior since the early 1960's to present. The objective of this study was to determine the evolution and changes in the ice-dam of the Perito Moreno glacier that started on November, 23 2012 and collapsed on January 19, 2013. Two images every 24 hours were acquired since October 2012 until February 2013, a total of 135 days. Image information was supported by ground data. Image and ground data was correlated with a 2D affine transformation. This technique allows the determination of the distortions in the images and estimating the values of scale factors. This, along with an accurate time-lapse interval, has produced accurate data for the analysis. In addition, changes in the level of the Brazo Rico lake were validated with direct data in order to determine the degree of uncertainty in the estimation of changes in the glacier. Based on the calculations, advance rates of the front of the Perito Moreno glacier were estimated at 0.67 m/d ± 0.003 m, and the tunnel evolution was also recorded.

Chemotaxis of Mesenchymal Stem Cells in a Microfluidic Device

ABSTRACTAdult bone marrow derived mesenchymal stem cells (MSCs) represent an important source of cells for tissue regeneration. Control of MSC migration and homing is still unclear. The goal of this study was to identify potent chemoattractants for MSCs and characterize MSC chemotaxis using a microfluidic device as a model system and assay platform. The three chemokines compared in this study were CXCL7, CXCL12, and AMD 3100.Microfluidic devices made of polydimethysiloxane (PDMS) were fabricated by soft lithography techniques and designed to generate a stable linear chemokine gradient. Cell movements in response to the gradient were captured by timelapse photos and tracked over 24 hours. Chemokine potency was measured via several chemotaxis parameters including: velocity in the direction of interest (V), center of mass (Mend), forward migration indice (YFMI). The migratory paths of the cells were mapped onto a displacement plot and compared.The following results were measured in the direction of interest (towards higher concentrations of chemokine): For velocity, only cells exposed to CXCL12 had a statistically significant (p=.014) average velocity (V=0.19 ± 0.07 um/min) when compared to the control condition (V=0.06 ±0 .04 um/min). For the center of mass, where the displacement of cells from their starting positions were compared, again only CXCL12 (Mend= 53.9 ± 10.8 um) stimulated statistically significant (p = .013) displacement of cells compared to the control condition (Mend = 19.3 ± 16.1 um). For the forward migration index, the efficiency of cell movement was measured. Indices in both the CXCL12 (YFIM = 0.19 ± 0.08) and CXCL7 (YFIM = 0.09 ±0.03) conditions were statistically significant (p = .023 for CXCL12 and p = .035 for CXCL7) when compared with the control index (YFIM = .04 ± .02).This study demonstrated the use of microfluidic devices as a viable platform for chemotaxis studies. A stable linear chemokine gradient was maintained over a long time scale to obtain cell migration results. CXCL12 was quantitatively determined to be the most potent chemoattractant in this research; these chemoattractive properties promote its use in future developments to control MSC homing.

Glacier velocities from time-lapse photos: technique development and first results from the Extreme Ice Survey (EIS) in Greenland

AbstractAutomated digital cameras were installed in May–June 2007 beside major West Greenland marine-terminating glaciers as part of the Extreme Ice Survey (EIS). EIS cameras began imaging the lowest 4 km2 of the glacier at hourly intervals throughout sunlit periods of the year. This study presents the development of techniques for quantifying glacier velocity from a single camera perspective. A Multi-Image/Multi-Chip matching procedure yields higher matching skill than conventional matching, and facilitates false-match rejection via a clustering scheme. The matching of motionless on-land features facilitates compensating camera motion. Ray projection to a known terrain elevation allows the assigning of scale to convert pixel displacements to velocity units. With the 10.2-megapixel camera system, velocities on relatively fast glaciers can be resolved at distances up to ∼4 km. At a distance of 2 km, a demonstrated precision of ∼0.5 pixels yields a ∼0.5 m footprint size. Daily velocities indicate progressive multi-day velocity accelerations associated with calving. Deceleration trends are associated with the regrowth of resistive stress after major calving. The higher observation frequency available to terrestrial photogrammetry indicates higher observed intra-seasonal velocity range than observable by the at-best weekly satellite snapshots.

Determining Hunting Season Waste of Deer by Following Fox Trails

proof plywood glued at all corners; the exterior is painted flat-black. Both are provided with hingehasps and padlocks which in turn can be locked to a chain and anchored to a tree. The joint between cover and chassis is sealed with a rubber gasket to prevent moisture from entering. The 6-volt battery housing is provided with a microswitch arranged to open the solenoid and exciter light circuits when the cover is removed. The eye is housed in plastic tubes 8 inches long, 4 inches O.D., mounted on yokes with fittings to allow vertical adjustment. The yokes are '4-inch rods welded to a %-inch steel peg for driving into the ground (Figs. 2, 4). When necessary, the entire yoke assembly is braced by additional supports to form a tripod-like affair. In operation the beam is directed across the animal pathway and adjusted for proper height and distance between the exciter light and solar cell. In studies to date, the light was covered with red cellophane, and an 8-day clock and dial thermometer were inserted in the camera field so as to appear in each exposure. Fig. 5 shows the kind of photograph one may expect to obtain with the apparatus. The recorder could be provided with a treadlemicroswitch in place of, or as a supplement to, the photoelectric switch. As indicated above, the camera could be set to take a motion picture series rather than a single frame. A modification of the circuits and use of additional time-delay contacts would make it possible to use the setup for making time-lapse photos at various intervals depending on the relay inserted. Other possibilities will likely become evident to users of the instrument. By purchasing a used camera and synchronizing xx: