scholarly journals 3D Reconstruction of Bird Flight using a Single Video Camera

2018 ◽  
Author(s):  
M.V. Srinivasan ◽  
H.D. Vo ◽  
I. Schiffner
Keyword(s):  
Prior Knowledge ◽  
Camera Calibration ◽  
Video Camera ◽  
Calibration Procedure ◽  
Three Dimensions ◽  
Multiple Cameras ◽  
Bird Flight ◽  
Video Cameras ◽  
Video Frames ◽  
Alternative Approach

ABSTRACTVideo cameras are finding increasing use in the study and analysis of bird flight over short ranges. However, reconstruction of flight trajectories in three dimensions typically requires the use of multiple cameras and elaborate calibration procedures. We present an alternative approach that uses a single video camera and a simple calibration procedure for the reconstruction of such trajectories. The technique combines prior knowledge of the bird’s wingspan with a camera calibration procedure that needs to be used only once in the system’s lifetime. The system delivers the exact 3D coordinates of the bird at the time of every full wing extension, and uses interpolated height estimates to compute the 3D positions of the bird in the video frames between successive wing extensions. The system is inexpensive, compact and portable, and can be easily deployed in the laboratory as well as the field.

A Comparison of Two Different Approaches to Camera Calibration in LSDM Photogrammetric Systems

2014 ◽  
Author(s):  
Ou Bai ◽  
Fiorenzo Franceschini ◽  
Maurizio Galetto ◽  
Luca Mastrogiacomo ◽  
Domenico A. Maisano
Keyword(s):  
Camera Calibration ◽  
Large Scale ◽  
Focal Length ◽  
Calibration Procedure ◽  
Optical Systems ◽  
Multiple Cameras ◽  
Dimensional Metrology ◽  
Distortion Parameters ◽  
Length Distortion

Large Scale Dimensional Metrology (LSDM) is a branch of metrology that deals with the measurement of objects with dimensions in the order of several meters. Optical systems, relying on the use of multiple cameras and photogrammetric techniques, are among the most used instruments in this field. These systems require a preliminary calibration procedure to determine some essential parameters, such as camera positions and orientations, focal length, distortion parameters, etc. A structured comparison between two different approaches to camera calibration is herein discussed.

scholarly journals Classification of Non-Conventional Ships Using a Neural Bag-Of-Words Mechanism

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1608 ◽  
Author(s):  
Dawid Polap ◽  
Marta Wlodarczyk-Sielicka
Keyword(s):  
Neural Network ◽  
Input Data ◽  
Automatic Identification ◽  
Bag Of Words ◽  
Specific Class ◽  
Classification Problems ◽  
Video Cameras ◽  
Video Frames ◽  
Alternative Approach

The existing methods for monitoring vessels are mainly based on radar and automatic identification systems. Additional sensors that are used include video cameras. Such systems feature cameras that capture images and software that analyzes the selected video frames. Methods for the classification of non-conventional vessels are not widely known. These methods, based on image samples, can be considered difficult. This paper is intended to show an alternative way to approach image classification problems; not by classifying the entire input data, but smaller parts. The described solution is based on splitting the image of a ship into smaller parts and classifying them into vectors that can be identified as features using a convolutional neural network (CNN). This idea is a representation of a bag-of-words mechanism, where created feature vectors might be called words, and by using them a solution can assign images a specific class. As part of the experiment, the authors performed two tests. In the first, two classes were analyzed and the results obtained show great potential for application. In the second, the authors used much larger sets of images belonging to five vessel types. The proposed method indeed improved the results of classic approaches by 5%. The paper shows an alternative approach for the classification of non-conventional vessels to increase accuracy.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

Occlusion Sequence Mining for Activity Discovery from Surveillance Videos

2008 ◽  
pp. 212-226 ◽  
Author(s):  
Prithwijit Guha ◽  
Amitabha Mukerjee ◽  
K. S. Venkatesh
Keyword(s):  
Prior Knowledge ◽  
Camera Calibration ◽  
Sequence Mining ◽  
Multiple Objects ◽  
Semantic Categories ◽  
Significant Events ◽  
Action Model ◽  
Blob Tracking ◽  
Temporal Sequences ◽  
Surveillance Applications

Complex multiobject interactions result in occlusion sequences, which are a visual signature for the event. In this work, multiobject interactions are tracked using a set of qualitative occlusion primitives derived on the basis of the persistence hypothesis: objects continue to exist even when hidden from view. Variable length temporal sequences of occlusion primitives are shown to be well correlated with many classes of semantically significant events. In surveillance applications, determining occlusion primitives is based on foreground blob tracking and requires no prior knowledge of the domain or camera calibration. New foreground blobs are identified as putative objects that may undergo occlusions, split into multiple objects, merge back again, and so forth. Significant activities are identified through temporal sequence mining; these bear high correlation with semantic categories (e.g., disembarking from a vehicle involves a series of splits). Thus, semantically significant event categories can be recognized without assuming camera calibration or any environment/object/action model priors.

scholarly journals Being held to account: Detainees’ perceptions of police body-worn cameras

2018 ◽  
Vol 52 (2) ◽  
pp. 174-192 ◽  
Author(s):  
Murray Lee ◽  
Emmeline Taylor ◽  
Matthew Willis
Keyword(s):  
Use Of Force ◽  
Video Camera ◽  
Activity Increase ◽  
Police Use Of Force ◽  
Video Cameras ◽  
Police Accountability ◽  
The World ◽  
Research Interviews ◽  
Perceptions Of Police ◽  
The Impact

Police organisations across the world are embracing body-worn video camera technology. The justification for this is to enhance public trust in police, provide transparency in policing activity, increase police accountability, reduce conflict between police and public, and to provide a police perspective of incidents and events. However, while the corpus of research into the efficacy and operational practicalities of police use of body-worn video cameras is developing, questions on some elements of their impact remain. The majority of scholarship has hitherto been evaluations focused on the impact of the cameras on police use of force and on the numbers of complaints against the police. Alternatively, this article explores body-worn video cameras from the perspective of police detainees, and specifically, detainees’ perceptions of the capacities of body-worn video cameras to deliver promised increased levels of accountability in policing. The article draws on a survey and research interviews with 907 police detainees across four Australian jurisdictions. While respondents largely support the use of body-worn video cameras they also identify a number of caveats. We conclude by suggesting that there are still impediments in body-worn video cameras to achieving the level of accountability promised by advocates and expected by the respondents.

scholarly journals Videodialysis: a pilot experience of telecare for assisted peritoneal dialysis

2019 ◽  
Vol 33 (1) ◽  
pp. 177-182 ◽  
Author(s):  
Giusto Viglino ◽  
Loris Neri ◽  
Sara Barbieri ◽  
Catia Tortone
Keyword(s):  
Clinical Care ◽  
Video Camera ◽  
Telemedicine System ◽  
Home Video ◽  
Video Cameras ◽  
Psychological Barriers ◽  
Know How ◽  
Remote Station ◽  
Audio Video

Abstract Background We report our experience with Videodialysis (VD), a new telemedicine system created in our Center to overcome physical, cognitive and psychological barriers to PD. Methods We analyzed the technical and clinical care results of VD in the period from 01/01/2009 to 12/31/2018. Results The VD components are: a Remote Station at the patient’s home (video camera, monitor, microphone, technological connectivity box), and a Control Station in the Center (PC with high resolution monitor, webcam, speakerphone) with software that manages 6 audio-video connections simultaneously as well as the Remote Station video cameras. In 2015 a second model of VD was designed to further improve ease of transport, installation, user interface, software functionality and connectivity. VD proved to be highly reliable during 21,000 connections, and easy to use by patients/caregivers without technological skills. During the observational period, 107 patients started PD; of these 77 had barriers to PD: in 15 we overcame the barriers by VD-Assisted PD and in 62 we used other modalities of Assisted PD. During a follow-up of 285 months on VD-Assisted, 5 patients died, 3 were transferred to HD (UFF; leakage; onset of barriers insurmountable with VD), 3 to traditional Assisted PD and 4 remained on VD-Assisted PD. Peritonitis incidence in VD-Assisted PD was 1/84.2 pt/mths, not significantly different to that of the patients not using VD. Sense of confidence was the aspect most highly-appreciated by VD-Assisted PD patients. Conclusions VD-Assisted PD is a reliable, safe system which requires no technological know-how and it is easy to use when self-care is not possible due to physical, cognitive or psychological barriers.

Conducting qualitative video research with young children

2018 ◽  
Vol 18 (3) ◽  
pp. 238-247 ◽  
Author(s):  
Kelly Shoecraft ◽  
Bev Flückiger
Keyword(s):  
Young Children ◽  
Video Recording ◽  
Video Camera ◽  
Practical Experience ◽  
Recording Technology ◽  
Content Type ◽  
Video Cameras ◽  
Video Recordings ◽  
Learning Through Play ◽  
Rich Data

Purpose The purpose of this paper is to explore the practical use of video cameras during a study with young children. Design/methodology/approach This paper investigates the use of video cameras in a research study of young children’s utilisation of semiotic tools to communicate during play interactions in a Francophone preschool classroom in British Columbia. It examines the practical in-the-moment decision making of the researcher to support children’s accommodation of the video camera in their play space and ensure rich data were recorded. Findings Children accommodated the video cameras in four distinct ways. These included: curiosity and investigation of the video cameras; engagement in the video recording process with the researcher; incorporation of the video cameras into their play; and disregard of it. Practical implications The findings suggest that video recordings can be an effective method of data collection with young children and provide rich sources of data of the children and their learning through play when the researcher is flexible and responsive and supports children’s accommodation of it. Originality/value Recent advances in recording technology have resulted in the increased use of video recordings as a resource for gathering empirical data in qualitative research. Whilst the ethical considerations related to the use of video recordings as data for analysis in research with young children have been the subject of some discussion (Flewitt, 2005), the practical experience of using video cameras has received less attention.

scholarly journals CAMERA CONSTANT IN THE CASE OF TWO MEDIA PHOTOGRAMMETRY

2015 ◽  
Vol XL-5/W5 ◽  
pp. 1-6 ◽  
Author(s):  
P. Agrafiotis ◽  
A. Georgopoulos
Keyword(s):  
Refractive Index ◽  
Camera Calibration ◽  
Focal Length ◽  
Calibration Procedure ◽  
Water Salinity ◽  
Clean Water ◽  
Object Distance ◽  
Calibration Methods ◽  
The One ◽  
Probable Relation

Refraction is the main cause of geometric distortions in the case of two media photogrammetry. However, this effect cannot be compensated and corrected by a suitable camera calibration procedure (Georgopoulos and Agrafiotis, 2012). In addition, according to the literature (Lavest et al. 2000), when the camera is underwater, the effective focal length is approximately equal to that in the air multiplied by the refractive index of water. This ratio depends on the composition of the water (salinity, temperature, etc.) and usually ranges from 1.10 to 1.34. It seems, that in two media photogrammetry, the 1.33 factor used for clean water in underwater cases does not apply and the most probable relation of the effective camera constant to the one in air is depending of the percentages of air and water within the total camera-to-object distance. This paper examines this relation in detail, verifies it and develops it through the application of calibration methods using different test fields. In addition the current methodologies for underwater and two-media calibration are mentioned and the problem of two-media calibration is described and analysed.

scholarly journals TWO-STEP CAMERA CALIBRATION METHOD DEVELOPED FOR MICRO UAV'S

2016 ◽  
Vol XLI-B1 ◽  
pp. 829-833 ◽  
Author(s):  
M. Gašparović ◽  
D. Gajski
Keyword(s):  
Camera Calibration ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Unmanned Aircraft ◽  
Sensor Calibration ◽  
Step Process ◽  
Complex Process ◽  
One Step ◽  
Accurate Procedure ◽  
Wide Angle Camera

The development of unmanned aerial vehicles (UAVs) and continuous price reduction of unmanned systems attracted us to this research. Professional measuring systems are dozens of times more expensive and often heavier than "amateur", non-metric UAVs. For this reason, we tested the DJI Phantom 2 Vision Plus UAV. Phantom’s smaller mass and velocity can develop less kinetic energy in relation to the professional measurement platforms, which makes it potentially less dangerous for use in populated areas. In this research, we wanted to investigate the ability of such non-metric UAV and find the procedures under which this kind of UAV may be used for the photogrammetric survey. It is important to emphasize that UAV is equipped with an ultra wide-angle camera with 14MP sensor. Calibration of such cameras is a complex process. In the research, a new two-step process is presented and developed, and the results are compared with standard one-step camera calibration procedure. Two-step process involves initially removed distortion on all images, and then uses these images in the phototriangulation with self-calibration. The paper presents statistical indicators which proved that the proposed two-step process is better and more accurate procedure for calibrating those types of cameras than standard one-step calibration. Also, we suggest two-step calibration process as the standard for ultra-wideangle cameras for unmanned aircraft.

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