Video motion magnification (MM) allows to turn a tiny movement recorded on video into an easily visible displacement. In this work, such techniques are employed to decrease the uncertainty of ...vision-based motion measurements. Previous works have already combined MM with vision-based measurement techniques, such as digital image correlation. This present study analyzes its applicability on simpler measurement techniques: pattern matching and edge detection, analyzing the accuracy improvements when measuring on a motion-magnified video. In addition, the suitability for these purposes of recent MM algorithms is tested, and the circumstances under which the magnification is beneficial are studied. As a result of the experiments, it is concluded that MM can increase the motion measurement accuracy, especially for small displacements, which could be considered an initial step for future quantifications of its applicability range.
Video motion magnification (VMM) techniques have recently gained attention as a low-cost accurate method for measuring microdisplacements. VMM techniques are known to have incorrect frequency ...responses when handling dynamic measurements consisting of multiple frequencies. New phase-based VMM method utilizing radial fractional steerable 2-D Hilbert transform is proposed and contrasted, in terms of the frequency response, with two other established VMM methods. Typical VMM workflow includes amplifying phase changes between subsequent video frames on many spatial frequencies separately using image pyramids, which are then collapsed forming new, motion-magnified video. In this paper, Hilbert transform is used to extract local phase changes. The modified Kullback-Leibler divergence was calculated between the spectral estimates of the time series of vibrating plate measured using a high-speed video camera and a reference time series synchronously acquired with high-precision air-coupled ultrasonic transducer. Time series consisted of micrometer range multicomponent vibrations (one, two, and three sine frequencies) recorded with different motion magnification factors. The results show that in the majority of cases, the proposed method, out of three considered, resulted in the most uniform frequency response and generated the lowest amount of unwanted frequencies. To conclude, a novel approach to VMM is proposed, which substantially improves frequency response and makes this technique more suitable for the measurements of phenomena consisting of multiple frequencies.
There are different techniques for measuring microdisplacements. The purpose of this paper was to ascertain whether a method of video motion magnification (VMM) can be used for measuring such ...displacements. For this, standard video devices (a digital single-lens reflex camera and a webcam) were used to record subtle movements of an object, and the results of the VMM technique were contrasted with an air-coupled ultrasonic sensing method that could achieve submicrometer accuracy. The results of the VMM technique highly correlate with those achieved using the ultrasonic sensor, showing that the former can accurately measure displacements in the range from about 5 to 40 μm from a distance of about 1 m. The temporal characteristics of the moving object were well preserved. The VMM technique is an alternative to other modalities for measuring microdisplacements and has the advantage of being noncontact, long-range, and relatively low-cost.
When using optical motion capture systems, increasing the number of cameras improves the visibility. However, the software used to deal with the information fusion from multiple cameras may ...compromise the accuracy of the system due to camera dropout, which can vary with time. In cadaver studies of radial head motion, increasing the number of cameras used by the motion capture system seemed to decrease the accuracy of the measurements. This study investigates the cause. The hypothesis was that errors in position can be induced when markers are obscured from and then restored to a camera's viewable range, as can happen in biomechanical studies. Accuracy studies quantified the capabilities of the motion capture system with precision translation and rotation movements. To illustrate the effect that abrupt perceived changes in a marker's position can have on the calculation of radial head travel, simulated motion experiments were performed. In these studies, random noise was added to simulated data, which obscured the resultant path of motion. Finally, camera-blocking experiments were performed in which precise movements were measured with a six-camera Vicon system and the errors between the actual and perceived motion were computed. During measurement, cameras were selectively blocked and restored to view. The maximum errors in translation and rotation were 3.7 mm and 0.837 deg, respectively. Repeated measures analysis of variance (ANOVAs) (alpha=0.05) confirmed that the camera-blocking influenced the results. Taken together, these results indicate that camera-switching can affect the observation of fine movements using a motion analysis system with a large number of cameras. One solution is to offer opportunity for user interaction in the software to choose the cameras used for each instant of time.
In this paper, we are concerned with two SIS epidemic reaction–diffusion models with mass action infection mechanism of the form
SI
, and study the spatial profile of population distribution as the ...movement rate of the infected individuals is restricted to be small. For the model with a constant total population number, our results show that the susceptible population always converges to a positive constant which is indeed the minimum of the associated risk function, and the infected population either concentrates at the isolated highest-risk points or aggregates only on the highest-risk intervals once the highest-risk locations contain at least one interval. In sharp contrast, for the model with a varying total population number which is caused by the recruitment of the susceptible individuals and death of the infected individuals, our results reveal that the susceptible population converges to a positive function which is non-constant unless the associated risk function is constant, and the infected population may concentrate only at some isolated highest-risk points, or aggregate at least in a neighborhood of the highest-risk locations or occupy the whole habitat, depending on the behavior of the associated risk function and even its smoothness at the highest-risk locations. Numerical simulations are performed to support and complement our theoretical findings.
Control of the movement and positioning are the most intensive tasks of automatic control and regulation. However, these problems must be solved in the automation objects such as assembly and ...production lines, manufacturing machines, conveyors, hoisting machines, packaging machines, filling lines for liquids, metal-working machines. One problem lies in the fact that all the real drives are connected to the actuators with not perfectly tough shafting, but has some elasticity. This leads to the difficulty of motion of the executive body of the drive automatic control systems which consists of signal source generating signal due optimum speed diagrams for small movements of electric drive’s actuating device and automatic regulation system, which allows to work out optimum speed diagrams for small movements of electric drive’s actuating device with ultra-precision. In this article were developed optimum speed diagram for small movements of ultra-precise electric drive with elastic shafting. Were have identified all parameters of diagrams and its range of existence and also developed a device for generating the optimum speed diagram for small movements of ultra-precise electric drive with elastic shafting. The implementation of the proposed hardware software complex will significantly improve the accuracy of motion actuators of various ultra- precise DC drives
By the time the nurse arrived on Sunday at eighth hour, Danny was awake again. Simeon and Danny’s parents had each shared part of the night at Danny’s beside, talking to each other or to her. They ...knew she could hear even if she couldn’t respond.
