Use Of Video Images Research Articles

Acquisition and Analysis of Dynamic Responses of a Historic Pedestrian Bridge using Video Image Processing

Video based tracking is capable of analysing bridge vibrations that are characterised by large amplitudes and low frequencies. This paper presents the use of video images and associated image processing techniques to obtain the dynamic response of a pedestrian suspension bridge in Cork, Ireland. This historic structure is one of the four suspension bridges in Ireland and is notable for its dynamic nature. A video camera is mounted on the river-bank and the dynamic responses of the bridge have been measured from the video images. The dynamic response is assessed without the need of a reflector on the bridge and in the presence of various forms of luminous complexities in the video image scenes. Vertical deformations of the bridge were measured in this regard. The video image tracking for the measurement of dynamic responses of the bridge were based on correlating patches in time-lagged scenes in video images and utilisinga zero mean normalisedcross correlation (ZNCC) metric. The bridge was excited by designed pedestrian movement and by individual cyclists traversing the bridge. The time series data of dynamic displacement responses of the bridge were analysedto obtain the frequency domain response. Frequencies obtained from video analysis were checked against accelerometer data from the bridge obtained while carrying out the same set of experiments used for video image based recognition.

Acquisition and Analysis of Dynamic Responses of a Historic Pedestrian Bridge using Video Image Processing

Video based tracking is capable of analysing bridge vibrations that are characterised by large amplitudes and low frequencies. This paper presents the use of video images and associated image processing techniques to obtain the dynamic response of a pedestrian suspension bridge in Cork, Ireland. This historic structure is one of the four suspension bridges in Ireland and is notable for its dynamic nature. A video camera is mounted on the river-bank and the dynamic responses of the bridge have been measured from the video images. The dynamic response is assessed without the need of a reflector on the bridge and in the presence of various forms of luminous complexities in the video image scenes. Vertical deformations of the bridge were measured in this regard. The video image tracking for the measurement of dynamic responses of the bridge were based on correlating patches in time-lagged scenes in video images and utilisinga zero mean normalised cross correlation (ZNCC) metric. The bridge was excited by designed pedestrian movement and by individual cyclists traversing the bridge. The time series data of dynamic displacement responses of the bridge were analysedto obtain the frequency domain response. Frequencies obtained from video analysis were checked against accelerometer data from the bridge obtained while carrying out the same set of experiments used for video image based recognition.

Importância da imagem vídeo em ortodontia - Uma revisão da literatura

IntroductionThe aim of this study was to evaluate the interest of capturing dynamic facial images in the diagnosis and treatment planning in orthodontics. MethodsWith the use of the PubMed search engine, we used the keywords “video AND orthodontics” and “dynamic analysis AND orthodontics”. The studies including patients with birth defects, syndromes or patients who had been previously submitted to orthodontic-orthognathic surgery were excluded. ResultsFrom the 178 articles, after analyzing all the abstracts, 15 articles were included. Only 8 were randomized controlled trials. ConclusionDespite the potential indicated the use of video images in the diagnosis and treatment planning in orthodontics, they shall function as a complement to conventional means. However, educational and motivational functions appear to bring out this technology compared to other methods.

Observation of microslips in series of actions for toothbrushing through use of video images

Observation of microslips in series of actions for toothbrushing through use of video images

Display type effects in military operational tasks using UAV video images

Employing advanced technology in combat can be helpful, but should be done with caution. Specifically, the use of video images retrieved from unmanned aerial vehicles (UAVs) by dismounted soldiers can be beneficial for presenting tactical and geographic information, when properly displayed. This work follows our previous studies on the type (e.g. size) of displays required by dismounted soldiers to process video feed from UAVs. Sixteen former infantry soldiers with no experience using UAV video feed participated. Four displays were examined in two scenarios (urban and rural) and in three different task domains (interpretation, orientation and response). Performance and subjective data were collected. Results show trends for differences between displays, scenarios, and task domain dependency. The most consistent trend marks the smallest display (personal digital assistant - PDA) to be unsuitable for this type of tasks.

Video Versus Reality: Infants' Attention and Affective Responses to Video and Live Presentations

Television viewing by infants has become very common, yet relatively little is known about infants' reactions to video compared to live events. We conducted two experiments in order to compare 9- or 10-month-old infants' behavioral reactions to live events and video presentations of those events. In the first experiment, infants' were shown video and live presentations shown consecutively; their affective reactions were consistent, indicating that video conveys meaning and emotional impact even in infancy. However, infants generally looked longer at, reached more to, showed more interest in, and exhibited more fear to the real stimuli. In a second experiment, infants were shown identical live and video events simultaneously; they looked much longer at the live presentations, further confirming that they distinguished live events from video and preferred to watch real events. Implications for infants' television viewing and the use of video images in infancy research are discussed.

On Some Recent Advances in Multimodal Surgery Simulation: A Hybrid Approach to Surgical Cutting and the Use of Video Images for Enhanced Realism

In this paper, we present some recent advances in realistic surgery simulation including novel algorithms for simulating surgical cutting and techniques of improving visual realism of the simulated scenarios using images. Simulation of surgical cutting is one of the most challenging tasks in the development of a surgery simulator. Changes in topology during simulation render precomputed data unusable. Moreover, the process is nonlinear and the underlying physics is complex. Therefore, fully realistic simulation of surgical cutting at real-time rates on single processor machines is possibly out of reach at the present time. In this paper, we present a hybrid approach to the simulation of surgical cutting procedures by combining a node-snapping technique with a physically based meshfree computational scheme, the point-associated finite field (PAFF) approach, and empirical data obtained from controlled cutting experiments. To enhance the realism of the rendered scenarios, we propose an innovative way of using images obtained from videos acquired during actual surgical processes. Using a combination of techniques such as image mosaicing and view-dependent texture-mapping, we have been able to achieve excellent realistic effects with desired tissue glistening as the camera position is changed. Realistic examples are presented to showcase the results.

Characteristics of lightning flashes striking the CN Tower below its tip

It has been observed that tall structures are sometimes struck by lightning below their tops. This phenomenon necessitates the use of special procedures for the protection of tall structures from lightning hazards. This paper focuses on the analysis of lightning flashes that struck the CN Tower below its tip over an extended period of time (1991–2005). Through the use of video images recorded during the reporting period, it was found that out of 404 flashes to the tower, only 16 hit the tower below its tip (3.96%). The distance between the tower's tip and the strike location varied from 5.4 to 70 m. Statistical analysis of flash characteristics of strikes below the tower's tip generally shows that the flash duration and the number of strokes per flash are considerably lower than those for the majority of cases, when the tower is struck at its tip. Furthermore, a trend of decrease in flash duration is found as the distance between the tower's tip and the strike location increases. Therefore, based on the analysis of the available data, lightning strikes below the top of a tall structure do not seem to pose greater danger than strikes to the structure's top, assuming that the structure is also protected along its sides. It is hoped that the presented observations and statistical analyses will be of value in the development of sophisticated measures against lightning hazards at elevated objects.

Divided Attention during Adaptation to Visual-Motor Roatation in an Endoscopic Surgery Simulator

Endoscopic surgery has gained popularity due to its minimally invasive nature and reduced patient recovery times. Due to the use of video images and long, thin surgical tools a surgeon's perceptual motor skills can be inhibited. Surgeons need to adapt to these perceptual-motor disruptions before operating on patients. Besides having to adapt to altered perceptual-motor conditions surgeons also have to deal with many other simultaneous demands, such as monitoring vital signs. Having to perform other simultaneous tasks during endoscopic surgery may divert or drain attention necessary for the complex movements demanded by the surgery. We investigated whether adaptive performance in an endoscopic surgery simulator suffered under dual-task conditions. Performance was significantly disrupted under altered perceptual-motor conditions during early simulator performance and the addition of a concurrent short-term memory task caused additional initial performance decrements, but those decrements were quickly overcome.

Changes in the microhemodynamics of nerve root retraction in patients with lumbar spinal canal stenosis.

Assessment of qualitative and quantitative changes in the microcirculation of nerve roots, such as the diameter of blood vessels and the low rate of erythrocytes, was observed during lumbar interbody fusion. To ascertain changes in the microcirculation of nerve roots before and after retraction during lumbar interbody fusion surgery. The changes in microhemodynamics caused by nerve root retraction have not yet been elucidated. Subjects were patients with lumbar spinal canal stenosis who underwent lumbar interbody fusion. Changes in the microcirculation of nerve roots were examined in the L5 nerve root in 26 patients and the S1 nerve root in 3 patients. Through the use of video images captured by contact endoscope and stored in a computer, erythrocytes were automatically followed to measure flow rate and the diameter of blood vessels. Plasma skimming, where blood cells and plasma flow separately, was seen in 3 of the 29 patients (10.3%) before retraction of the nerve root and in 8 of the 29 patients (27.6%) following retraction. Intravascular erythrocyte agglutination, when erythrocytes flow in clumps due to changes in the charge state of erythrocytes, was seen in blood vessels larger than 100 microm in 3 patients (10.3%) after retraction. Following nerve root retraction, the flow rate of erythrocytes through blood vessels decreased an average of 23.9% (P< 0.005). A contact endoscope was used to observe the microhemodynamics of nerve roots before and after retraction of the nerve root during lumbar interbody fusion surgery, and a decrease in the flow rate of erythrocytes was observed.

A novel telemedicine method for viewing the open surgical field.

The surgical theater has undergone a series of transformations from an open stadium-like environment to the closed environment of minimally invasive endoscopic surgery. Paradoxically, evolution from open surgery performed under direct vision to closed surgery performed through use of video images has been accompanied by improved viewing of the operative field by student observers. The objective of these experiments was to determine if a laparoscope mounted on the operating table during open surgery would provide students a better view of the operative field than that provided while standing behind the operating surgeon or via an optimally positioned hand-held video camera. An endoscopic video camera and telescope were attached to an operating table by an Alpha Virtual Port, which facilitates use of the laparoscope in open surgery by fixing it to the operating table in the position of interest. Additional imaging systems were set up so as to simulate viewing of the surgical field by direct vision or a hand-held video camera. Common objects were placed on the operating table in mock surgical fields of various depth-to-aperture ratios. Images of these surgical fields were obtained by each of these systems and placed in a Web-based tool. Eleven people with a wide range of medical training evaluated the images and determined that the Alpha Port-mounted surgical telescope provided optimal visibility of the mock open surgical field. The benefit of use of the mounted telescope was more pronounced as the depth-to-aperture ratio of the surgical field increased. Use of the Alpha Port-mounted laparoscope in open surgical procedures improves student viewing of the open surgical field.

Cambios morfológicos costeros en lsla del Carmen. Campeche, por el paso del huracán "Roxanne"

Con base en la interpretación de imágenes verticales de video adquiridas desde un helicóptero, se realizó un reconocimiento de los estragos causados por el paso del huracán "Roxanne" en la costa de la Isla del Carmen, Campeche, en octubre de 1995. Se identifican procesos geomorfológicos y formas resultantes que caracterizan a la línea de costa como recesiva durante el evento ciclónico, aunque localmente se aprecian algunos rasgos de acumulación en sectores reducidos. Los sitios más afectados corresponden a antiguos canales, hoy obturados, cuyo funcionamiento es reactivado durante los eventos ciclónicos extraordinarios. Se concluye, igualmente, acerca de la utilidad de las imágenes de video en la evaluación expedita del territorio y de la detección de daños a la infraestructura.

Can video images imitate real stimuli in animal behaviour experiments?

ABSTRACTThe use of video images in place of natural stimuli in animal behaviour experiments is reviewed. Unlike most other artificial means of stimulus presentation, video stimuli can depict complex moving objects such as other animals, preserving the temporal and spatial patterns of movement precisely as well as colour and sounds for repeated playback. Computer editing can give flexibility and control over all elements of the stimulus. A variety of limitations of video image presentation are also considered. Televisions and video monitors are designed with human vision in mind, and some non‐human animals that differ in aspects of visual processing such as their colour vision, critical flicker‐fusion threshold, perception of depth and visual acuity, may perceive video images differently to ourselves. The failure of video stimuli to interact with subjects can be a drawback for some studies. For video to be useful, it is important to confirm that the subject animal responds to the image in a comparable way to the real stimulus, and the criteria used to assess this are discussed. Finally, the contribution made by video studies to date in the understanding of animal visual responses is considered, and recommendations as to the future uses of video are made.

Conspecific Recognition in Pigeons (Columba Livia) Using Dynamic Video Images

AbstractVideo images of pigeons were used to examine the degree to which these images are equivalent to real live conspecifics by analyzing the natural behaviors of pigeons in the presence of each stimulus. Three aspects of courtship display (i.e. bowing, tail-dragging, and vocalizations) were selected and the display duration for each was measured. When videotaped images of female pigeons were presented as stimuli, the display duration by male pigeons was not significantly different from that for the live birds. In contrast, the subjects showed much shorter, or no, displays to the video images of a non-pigeon bird (cockatoo) and an empty chamber. The results suggest that the video images of pigeons contained necessary information to trigger the courtship behaviors. Furthermore, the present study examined which features of the video images were critical for triggering the displays by manipulating the images. Thus, the subjects' behaviors were more vigorous (1) when video images were in motion rather than still, and (2) when the head-only region was visible rather than the body-only region. These results suggest that motion and facial/head characteristics are important features. Collectively, the results indicate that the use of video images as stimuli and courtship displays as measures provide a useful method to study the visual recognition of conspecifics in birds.

Visualisation and computer assisted learning: the role of videodiscs

AbstractVisualisation is a powerful tool in research; visual, dynamic and interactive representations help learners using simulations and microworlds to gain qualitative understanding of concepts. Recorded video can bring reality to computer assisted learning. The author argues that the two approaches, while complementary, are not entirely compatible; that is, the use of video images in simulations often implies a trade‐off against qualitative modelling power. Appropriate roles for video are discussed in the light of this contention.

On the use of video images as social stimuli in birds: audience effects on alarm calling

The production of certain vocal signals in birds, such as food and alarm calls, is potentiated by the presence of an appropriate audience, and reduced when the signaller is alone. In this study, it is shown that the potentiating effects of a female chicken, Gallus domesticus, on the production of aerial alarm calls by a cockerel can be perfectly replicated by substituting the video image of a hen, with soundtrack, for a live vocalizing hen. The potentiating effect of a live conspecific audience is greater than that of a live bobwhite quail, Colinus virginianus, which is in turn more effective than an empty cage. Similarly, a hen videotape with sound is more effective than a bobwhite videotape with sound, which is in turn more effective than a videotape of an empty cage. A second experiment, using various combinations of the optical and sound tracks of videotapes, revealed that stimulation by both sensory modalities contributes to the audience effect. In this situation, visual and auditory cues play roughly equivalent roles. These experiments open up new prospects for the analysis of processes of visual communication in birds. For example, a domestic hen is normally more active than a bobwhite quail. By selecting bobwhite videotapes with high activity rates, it is demonstrated that the species specificity of the audience effect persists with activity rates reversed in favour of the heterospecific stimulus.

Video Digitizing Analysis System

The use of video images in biomechanical analyses has become more realistic since the introduction of the shuttered video camera. Although recording rates are still limited to 60 Hz, exposure times can be reduced to prevent blurring in most situations. This paper presents a system for manually digitizing video images, a system that utilizes a video overlay board to place a set of cross hairs directly on a previously recorded or live video image. A cursor is used to move the cross hairs over required points. A BASIC program was written for a IBM PC-AT computer to accomplish this task. Video images of a known set of points were digitized, and calculated distances between points were compared to real distances. The mean of the observed errors was 0.79%. It was concluded that this digitizing system, within the limitations of video resolution, yielded digitizing errors similar in magnitude to those observed in cinematographic analyses.