scholarly journals Step by step: reconstruction of terrestrial animal movement paths by dead-reckoning

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
O. R. Bidder ◽  
J. S. Walker ◽  
M. W. Jones ◽  
M. D. Holton ◽  
P. Urge ◽  
...  
Keyword(s):  
Animal Movement ◽  
Dead Reckoning ◽  
Terrestrial Animal

scholarly journals Circles within spirals, wheels within wheels; Body rotation facilitates critical insights into animal behavioural ecology

2021 ◽  
Author(s):  
◽  
Richard M. Gunner
Keyword(s):  
Resource Selection ◽  
Animal Movement ◽  
Movement Ecology ◽  
Dead Reckoning ◽  
Space Use ◽  
Behavioural Ecology ◽  
Motion Sensors ◽  
Fine Scale ◽  
Body Rotation ◽  
Model Species

How animals behave is fundamental to enhancing their lifetime fitness, so defining how animals move in space and time relates to many ecological questions, including resource selection, activity budgets and animal movement networks. Historically, animal behaviour and movement has been defined by direct observation, however recent advancements in biotelemetry have revolutionised how we now assess behaviour, particularly allowing animals to be monitored when they cannot be seen. Studies now pair ‘convectional’ radio telemetries with motion sensors to facilitate more detailed investigations of animal space-use. Motion sensitive tags (containing e.g., accelerometers and magnetometers) provide precise data on body movements which characterise behaviour, and this has been exemplified in extensive studies using accelerometery data, which has been linked to space-use defined by GPS. Conversely, consideration of body rotation (particularly change in yaw) is virtually absent within the biologging literature, even though various scales of yaw rotation can reveal important patterns in behaviour and movement, with animal heading being a fundamental component characterising space-use. This thesis explores animal body angles, particularly about the yaw axis, for elucidating animal movement ecology. I used five model species (a reptile, a mammal and three birds) to demonstrate the value of assessing body rotation for investigating fine-scale movement-specific behaviours. As part of this, I advanced the ‘dead-reckoning’ method, where fine-scale animal movement between temporally poorly resolved GPS fixes can be deduced using heading vectors and speed. I addressed many issues with this protocol, highlighting errors and potential solutions but was able to show how this approach leads to insights into many difficult-to-study animal behaviours. These ranged from elucidating how and where lions cross supposedly impermeable man-made barriers to examining how penguins react to tidal currents and then navigate their way to their nests far from the sea in colonies enclosed within thick vegetation.

scholarly journals How often should dead-reckoned animal movement paths be corrected for drift?

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Richard M. Gunner ◽  
Mark D. Holton ◽  
David M. Scantlebury ◽  
Phil Hopkins ◽  
Emily L. C. Shepard ◽  
...  
Keyword(s):  
Animal Movement ◽  
Radio Telemetry ◽  
Dead Reckoning ◽  
Foraging Strategies ◽  
Battery Life ◽  
Magellanic Penguin ◽  
Position Correction ◽  
Movement Type ◽  
Phaethon Rubricauda ◽  
Straight Lines

Abstract Background Understanding what animals do in time and space is important for a range of ecological questions, however accurate estimates of how animals use space is challenging. Within the use of animal-attached tags, radio telemetry (including the Global Positioning System, ‘GPS’) is typically used to verify an animal’s location periodically. Straight lines are typically drawn between these ‘Verified Positions’ (‘VPs’) so the interpolation of space-use is limited by the temporal and spatial resolution of the system’s measurement. As such, parameters such as route-taken and distance travelled can be poorly represented when using VP systems alone. Dead-reckoning has been suggested as a technique to improve the accuracy and resolution of reconstructed movement paths, whilst maximising battery life of VP systems. This typically involves deriving travel vectors from motion sensor systems and periodically correcting path dimensions for drift with simultaneously deployed VP systems. How often paths should be corrected for drift, however, has remained unclear. Methods and results Here, we review the utility of dead-reckoning across four contrasting model species using different forms of locomotion (the African lion Panthera leo, the red-tailed tropicbird Phaethon rubricauda, the Magellanic penguin Spheniscus magellanicus, and the imperial cormorant Leucocarbo atriceps). Simulations were performed to examine the extent of dead-reckoning error, relative to VPs, as a function of Verified Position correction (VP correction) rate and the effect of this on estimates of distance moved. Dead-reckoning error was greatest for animals travelling within air and water. We demonstrate how sources of measurement error can arise within VP-corrected dead-reckoned tracks and propose advancements to this procedure to maximise dead-reckoning accuracy. Conclusions We review the utility of VP-corrected dead-reckoning according to movement type and consider a range of ecological questions that would benefit from dead-reckoning, primarily concerning animal–barrier interactions and foraging strategies.

scholarly journals Dead-Reckoning Animal Movements in R – A Reappraisal Using Gundog.Tracks

2021 ◽  
Author(s):  
Richard Michael Gunner ◽  
Mark D Holton ◽  
Mike D Scantlebury ◽  
Louis van Schalkwyk ◽  
Holly M English ◽  
...  
Keyword(s):  
Animal Movement ◽  
Movement Ecology ◽  
Dead Reckoning ◽  
Supplementary Information ◽  
Fine Scale ◽  
Magellanic Penguin ◽  
True Location ◽  
Position Correction ◽  
Ground Truthing ◽  
Aerial Systems

Abstract Background Fine-scale data on animal position are increasingly enabling us to understand the details of animal movement ecology and dead-reckoning, a technique integrating motion sensor-derived information on heading and speed, can be used to reconstruct fine-scale movement paths at sub-second resolution, irrespective of the environment. On its own however, the dead-reckoning process is prone to cumulative errors, so that position estimates quickly become uncoupled from true location. Periodic ground-truthing with aligned location data (e.g., from global positioning technology) can correct for this drift between Verified Positions (VPs). Yet relatively few bio-logging studies have adopted this approach due to an apparent inaccessibility of the complex analytical processes involved. We present step-by-step instructions for implementing Verified Position Correction (VPC) dead-reckoning in R using the tilt-compensated compass method, accompanied by the mathematical protocols underlying the code and improvements and extensions of this technique to reduce the trade-off between VPC rate and dead-reckoning accuracy. These protocols are all built into a user-friendly, fully-annotated VPC dead-reckoning R function; Gundog.Tracks, with multi-functionality to reconstruct animal movement paths across terrestrial, aquatic, and aerial systems, provided within the supplementary information as well as online (GitHub). Results The Gundog.Tracks function is demonstrated on three contrasting model species (the African lion Panthera leo, the Magellanic penguin Spheniscus magellanicus, and the Imperial cormorant Leucocarbo atriceps) moving on land, in water and in air, respectively. We show the effect of uncorrected errors in speed estimations, heading inaccuracies and infrequent VPC rate and demonstrate how these issues can be addressed. Conclusions The function provided will allow anyone familiar with R to dead-reckon animal tracks readily and accurately, as the key complex issues are dealt with by Gundog.Tracks. This will help the community to consider and implement a valuable, but often overlooked method of reconstructing high-resolution animal movement paths across diverse species and systems without requiring a bespoke application.

scholarly journals Opportunities for the application of advanced remotely-sensed data in ecological studies of terrestrial animal movement

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Wiebke Neumann ◽  
Sebastian Martinuzzi ◽  
Anna B Estes ◽  
Anna M Pidgeon ◽  
Holger Dettki ◽  
...  
Keyword(s):  
Animal Movement ◽  
Remotely Sensed ◽  
Ecological Studies ◽  
Remotely Sensed Data ◽  
Terrestrial Animal

scholarly journals How Often Should Dead-Reckoned Animal Movement Paths be Corrected for Drift?

2021 ◽  
Author(s):  
Richard Michael gunner ◽  
Mark D Holton ◽  
Mike D Scantlebury ◽  
Phil Hopkins ◽  
Emily LC Shepard ◽  
...  
Keyword(s):  
Animal Movement ◽  
Radio Telemetry ◽  
Dead Reckoning ◽  
Foraging Strategies ◽  
Battery Life ◽  
Magellanic Penguin ◽  
Position Correction ◽  
Movement Type ◽  
Phaethon Rubricauda ◽  
Straight Lines

Abstract BackgroundUnderstanding what animals do in time and space is important for a range of ecological questions, however accurate estimates of how animals use space is challenging. Within the use of animal-attached tags, radio telemetry (including the Global Positioning System (GPS)) is typically used to verify an animal’s location periodically. Straight lines are typically drawn between these ‘Verified Positions’ (VPs) so the interpolation of space-use is limited by the temporal- and spatial resolution of the system’s measurement. As such, parameters such as route-taken and distance travelled can be poorly represented when using VP systems alone. Dead-reckoning has been suggested as a technique to improve the accuracy and resolution of reconstructed movement paths, whilst maximising battery life of VP systems. This typically involves deriving travel vectors from motion sensor systems and periodically correcting path dimensions for drift with simultaneously deployed VP systems. How often paths should be corrected for drift, however, has remained unclear.Methods & ResultsHere, we review the utility of dead-reckoning across four contrasting model species using different forms of locomotion (the African lion Panthera leo, the Red-tailed tropicbird Phaethon rubricauda, the Magellanic penguin Spheniscus magellanicus, and the Imperial cormorant Leucocarbo atriceps). Simulations were performed to examine the extent of dead-reckoning error, relative to VPs, as a function of Verified Position correction (VP correction) rate and the effect of this on estimates of distance moved. Dead-reckoning error was greatest for animals travelling within air and water. We demonstrate how sources of measurement error can arise within VP-corrected dead-reckoned tracks and propose advancements to this procedure to maximise dead-reckoning accuracy.ConclusionsWe review the utility of VP-corrected dead-reckoning according to movement type and consider a range of ecological questions that would benefit from dead-reckoning, primarily concerning animal-barrier interactions and foraging strategies.

scholarly journals Dead-reckoning animal movements in R: a reappraisal using Gundog.Tracks

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Richard M. Gunner ◽  
Mark D. Holton ◽  
Mike D. Scantlebury ◽  
O. Louis van Schalkwyk ◽  
Holly M. English ◽  
...  
Keyword(s):  
Animal Movement ◽  
Movement Ecology ◽  
Dead Reckoning ◽  
Fine Scale ◽  
Magellanic Penguin ◽  
True Location ◽  
Position Correction ◽  
Ground Truthing ◽  
User Friendly ◽  
Aerial Systems

Abstract Background Fine-scale data on animal position are increasingly enabling us to understand the details of animal movement ecology and dead-reckoning, a technique integrating motion sensor-derived information on heading and speed, can be used to reconstruct fine-scale movement paths at sub-second resolution, irrespective of the environment. On its own however, the dead-reckoning process is prone to cumulative errors, so that position estimates quickly become uncoupled from true location. Periodic ground-truthing with aligned location data (e.g., from global positioning technology) can correct for this drift between Verified Positions (VPs). We present step-by-step instructions for implementing Verified Position Correction (VPC) dead-reckoning in R using the tilt-compensated compass method, accompanied by the mathematical protocols underlying the code and improvements and extensions of this technique to reduce the trade-off between VPC rate and dead-reckoning accuracy. These protocols are all built into a user-friendly, fully annotated VPC dead-reckoning R function; Gundog.Tracks, with multi-functionality to reconstruct animal movement paths across terrestrial, aquatic, and aerial systems, provided within the Additional file 4 as well as online (GitHub). Results The Gundog.Tracks function is demonstrated on three contrasting model species (the African lion Panthera leo, the Magellanic penguin Spheniscus magellanicus, and the Imperial cormorant Leucocarbo atriceps) moving on land, in water and in air. We show the effect of uncorrected errors in speed estimations, heading inaccuracies and infrequent VPC rate and demonstrate how these issues can be addressed. Conclusions The function provided will allow anyone familiar with R to dead-reckon animal tracks readily and accurately, as the key complex issues are dealt with by Gundog.Tracks. This will help the community to consider and implement a valuable, but often overlooked method of reconstructing high-resolution animal movement paths across diverse species and systems without requiring a bespoke application.

Integrated Circuit Device Repair Using FIB System: Tips, Tricks, and Strategies

1999 ◽  
Author(s):  
K. N. Hooghan ◽  
K. S. Wills ◽  
P.A. Rodriguez ◽  
S.J. O’Connell
Keyword(s):  
Integrated Circuit ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Dead Reckoning ◽  
Physical Damage ◽  
Art Form ◽  
Metal Levels ◽  
Potential Damage ◽  
On Chip ◽  
Beam Currents

Abstract Device repair using Focused Ion Beam(FIB) systems has been in use for most of the last decade. Most of this has been done by people who have been essentially self-taught. The result has been a long learning curve to become proficient in device repair. Since a great deal of the problem is that documentation on this “art form” is found in papers from many different disciplines, this work attempts to summarize all of the available information under one title. The primary focus of FIB device repair is to ensure and maintain device integrity and subsequently retain market share while optimizing the use of the instrument, usually referred to as ‘beam time’. We describe and discuss several methods of optimizing beam time. First, beam time should be minimized while doing on chip navigation to reach the target areas. Several different approaches are discussed: dead reckoning, 3-point alignment, CAD-based navigation, and optical overlay. Second, after the repair areas are located and identified, the desired metal levels must be reached using a combination of beam currents and gas chemistries, and then filled up and strapped to make final connections. Third, cuts and cleanups must be performed as required for the final repair. We will discuss typical values of the beam currents required to maintain device integrity while concurrently optimizing repair time. Maintaining device integrity is difficult because of two potentially serious interactions of the FIB on the substrate: 1) since the beam consists of heavy metal ions (typically Gallium) the act of imaging the surface produces some physical damage; 2) the beam is positively charged and puts some charge into the substrate, making it necessary to use great care working in and around capacitors or active areas such as transistors, in order to avoid changing the threshold voltage of the devices. Strategies for minimizing potential damage and maximizing quality and throughput will be discussed.

Sign in / Sign up

Export Citation Format

Share Document