Target Circle Research Articles

The dynamic adjustment of saccades during Chinese reading: Evidence from eye movements and simulations.

This article reports an eye-movement experiment in which participants scanned continuous sequences of Landolt-Cs for target circles to examine the visual and oculomotor constraints that might jointly determine where the eyes move in a task that engages many of the perceptual and motor processes involved in Chinese reading but without lexical or linguistic processing. The lengths of the saccades entering the Landolt-C clusters were modulated by the processing difficulty (i.e., gap sizes) of those clusters. Simulations using implemented versions of default-targeting (Yan, Kliegl, Richter, Nuthmann, & Shu, 2010) versus dynamic-adjustment (Liu, Reichle, & Li, 2016) models of saccadic targeting indicated that the latter provided a better account of our participants' eye movements, further supporting the hypothesis that Chinese readers "decide" where to move their eyes by adjusting saccade length in response to processing difficulty rather than by selecting default saccade targets. We discuss this hypothesis in relation to both what is known about saccadic targeting during the reading of English versus Chinese and current models of eye-movement control in reading. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Amplified visual detection of microRNA-378 through a T4 DNA ligase-mediated circular template specific to target and target-triggering rolling circle amplification

MicroRNA-378 (miRNA-378) is widely regarded as a novel noninvasive serum biomarker for early detection of gastric cancer.

Adaptive Fuzzy Tree System for Target Tracking in Mission Critical Sensor Networks

The emergence of mobile sensors dramatically improves the availability of mission critical sensors and sensor networks (MC-SSN), enabling it to be utilized in more challenging tasks. However, current researches aimed to target tracking in mobile MC-SSN are very limited. This paper first proposes an adaptive fuzzy tree system (AFS) for target tracking in MC-SSN. To avoid oversimplifying the target mobile pattern, which is unrealistic in real tracking tasks, we introduce the target circle into the model considerations to add a bit of uncertainty about the target position. At each time step of the tracking process, strategy-selection layer will activate the pursuit strategy or the diffusion strategy for the specific situation, which makes the system more intelligent and can be applicable to various scenarios. The pursuit strategy is built by a two-layer fuzzy tree to select and mobilize sensors that have not detected target, while the diffusion strategy uses a fuzzy inference system to balance the density of detected sensors. And all the hyper-parameters are tuned by particle swarm optimization (PSO). We performed a large number of simulations with two target trajectories: line and irregular. The simulation results show that the AFS significantly outperforms the state-of-the-art algorithm. Moreover, it is highly robust to various target motion patterns, making it competent for a variety of real target tracking scenarios.

Changes in intentional binding effect during a novel perceptual-motor task.

Perceptual-motor learning describes the process of improving the smoothness and accuracy of movements. Intentional binding (IB) is a phenomenon whereby the length of time between performing a voluntary action and the production of a sensory outcome during perceptual-motor control is perceived as being shorter than the reality. How IB may change over the course of perceptual-motor learning, however, has not been explicitly investigated. Here, we developed a set of IB tasks during perceptual-motor learning. Participants were instructed to stop a circular moving object by key press when it reached the center of a target circle on the display screen. The distance between the center of the target circle and the center of the moving object was measured, and the error was used to approximate the perceptual-motor performance index. This task also included an additional exercise that was unrelated to the perceptual-motor task: after pressing the key, a sound was presented after a randomly chosen delay of 200, 500, or 700 ms and the participant had to estimate the delay interval. The difference between the estimated and actual delay was used as the IB value. A cluster analysis was then performed using the error values from the first and last task to group the participants based on their perceptual-motor performance. Participants showing a very small change in error value, and thus demonstrating a small effect of perceptual-motor learning, were classified into cluster 1. Those who exhibited a large decrease in error value from the first to the last set, and thus demonstrated a strong improvement in perceptual-motor performance, were classified into cluster 2. Those who exhibited perceptual-motor learning also showed improvements in the IB value. Our data suggest that IB is elevated when perceptual-motor learning occurs.

Novel Boundary Edge Detection for Accurate 3D Surface Profilometry Using Digital Image Correlation

Digital image correlation (DIC) has emerged as a popular full-field surface profiling technique for analyzing both in-plane and out-of-plane dynamic structures. However, conventional DIC-based surface 3D profilometry often yields erroneous contours along surface edges. Boundary edge detection remains one of the key issues in DIC because a discontinuous surface edge cannot be detected due to optical diffraction and height ambiguity. To resolve the ambiguity of edge measurement in optical surface profilometry, this study develops a novel edge detection approach that incorporates a new algorithm using both the boundary subset and corner subset for accurate edge reconstruction. A pre-calibrated gauge block and a circle target were reconstructed to prove the feasibility of the proposed approach. Experiments on industrial objects with various surface reflective characteristics were also conducted. The results showed that the developed method achieved a 15-fold improvement in detection accuracy, with measurement error controlled within 1%.

Discreet motor skill acquisition: effect of number of visual demonstrations

This experiment investigated the effect of number of visual demonstrations on the acquisition of discreet motor skill. Seventy-four college students of both sex participated in this study. The participants observed a visual model twice or ten times. In the acquisition phase, the participants were asked to throw a dart with postero-anterior movement into a circle target until reach a learning criterion. In transfer tests no difference between groups was found in the analysis of score. However, ten demonstrations were more effective than twice as regards performance of the correct pattern of movement and the number of subjects who reached the performance criterion. The results show that the number of demonstrations has a specially marked effect on movement pattern.

Алгоритм полиномиальной сложности для поиска соответствующих точек на основе эпиполярной геометрии

Point correspondence problem is one of the key problems in computer vision. There are several approaches for solving this problem, such as descriptor-based approach, an approach that is based on epipolar geometry, as well as hybrid methods. This article reviews point matching by the means of epipolar geometry. These methods are intended to be used with a photogrammetric system that is currently under development. The system uses artificial circular retroreflective targets. We propose to use multipartite weighted undirected graph as a mathematical model of the point correspondence problem. Its vertices represent images of the circle targets in the photos, while its edges define the set of images that satisfy mutual epipolar constraint. We show the exact solution of the point correspondence problem via superclique, and show that the exact solution has exponential time complexity. We also review various heuristic approaches to point matching. Heuristic algorithms do not always provide an exact solution of the problem, but they have much lower time complexity. The architecture of our photogrammetric systems makes it possible to use such fast heuristic point matching algorithms: all the discrepancies will be automatically determined and filtered out in the further stages of photogrammetric reconstruction. This allows to iteratively find an exact reconstruction of the scene in reasonable time. We propose a new polynomial point matching algorithm, and estimate its time complexity as O(n^4). We also estimate its efficiency and performance in comparison to other in-house algorithms, as well as in comparison to H.-G. Maas’s algorithms. Our new algorithm outperforms all competitors.

Fast vision‐based autonomous detection of moving cooperative target for unmanned aerial vehicle landing

AbstractWe propose a fast and effective method, fast target detection (FTD), to detect the moving cooperative target for the unmanned aerial vehicle landing, and the target is composed of double circles and a cross. The purpose of our strategy is to land on the target. The FTD method needs to detect the target at the high and low heights. At the high height, the target appears completely and stably in the camera field. The FTD method can detect the circle and cross to rapidly reach the target center, named cross and circle–FTD (). To detect the cross, we propose a slope distance equation to obtain the distance between two slopes. The proposed slopes cluster method, based on the distance equation and K‐means, is used to determine the cross center. At the low height, the target appears incompletely and unstably. Therefore, FTD methods detect only the cross, named cross–FTD (). We extract the cross features ( CFs) based on line segments. Then, four CFs are combined based on graph theory. Experiments on our four datasets show that FTD has rapid speed and good performance. (Our method is implemented in C++ and is available at https://github.com/Li-Zhaoxi/UAV-Vision-Servo.) On the Mohamed Bin Zayed International Robotics Challenge datasets made we constructed, detects the target from a image approximately per pipeline with F‐measure and tracks target approximately per pipeline with F‐measure. detects centers from a image at approximately per image with F‐measure.

A calibration method for stereovision system based on solid circle target

All kinds of calibration methods have many optimal variables and complicated computation. How to calibrate stereovision system rapidly and precisely is always a pressing problem in the field of visual measurement. Therefore, a calibration method for stereovision system based on solid circle target is proposed in the present paper. A solid circle calibration pattern is adopted to calibrate the stereovision system. The centers of solid circles on calibration pattern are extracted by Canny-Zernike combination algorithm and sorted based on a triangle mark on calibration pattern. According to the pinhole camera model, the intrinsic and extrinsic parameters of left and right cameras are firstly obtained. Then, the distortion model including four parameters is adopted, Levenberg-Marquardt algorithm is used to separately optimize the image coordinates of projection of 3D point on the imaging plane of left and right cameras, the intrinsic parameters including distortion coefficients and extrinsic parameters of stereovision system are acquired in this step. In the last step, the distance between two centers on diagonal direction of calibration pattern is regarded as the constraint to further optimize the extrinsic parameters of stereovision system. Furthermore, a calibration software for stereovision system based on solid circle target is compiled with MATLAB, and the comparison test of two calibration methods and two calibration patterns are performed in lab. Results show that the proposed method has a higher precision, can automatically proceed calibration and can be widely used in engineering.

Motor Planning Error: Toward Measuring Cognitive Frailty in Older Adults Using Wearables.

Practical tools which can be quickly administered are needed for measuring subtle changes in cognitive–motor performance over time. Frailty together with cognitive impairment, or ‘cognitive frailty’, are shown to be strong and independent predictors of cognitive decline over time. We have developed an interactive instrumented trail-making task (iTMT) platform, which allows quantification of motor planning error (MPE) through a series of ankle reaching tasks. In this study, we examined the accuracy of MPE in identifying cognitive frailty in older adults. Thirty-two older adults (age = 77.3 ± 9.1 years, body-mass-index = 25.3 ± 4.7 kg/m2, female = 38%) were recruited. Using either the Mini-Mental State Examination or Montreal Cognitive Assessment (MoCA), 16 subjects were classified as cognitive-intact and 16 were classified as cognitive-impaired. In addition, 12 young-healthy subjects (age = 26.0 ± 5.2 years, body-mass-index = 25.3 ± 3.9 kg/m2, female = 33%) were recruited to establish a healthy benchmark. Subjects completed the iTMT, using an ankle-worn sensor, which transforms ankle motion into navigation of a computer cursor. The iTMT task included reaching five indexed target circles (including numbers 1-to-3 and letters A&B placed in random order) on the computer-screen by moving the ankle-joint while standing. The ankle-sensor quantifies MPE through analysis of the pattern of ankle velocity. MPE was defined as percentage of time deviation between subject’s maximum ankle velocity and the optimal maximum ankle velocity, which is halfway through the reaching pathway. Data from gait tests, including single task and dual task walking, were also collected to determine cognitive–motor performance. The average MPE in young-healthy, elderly cognitive-intact, and elderly cognitive-impaired groups was 11.1 ± 5.7%, 20.3 ± 9.6%, and 34.1 ± 4.2% (p < 0.001), respectively. Large effect sizes (Cohen’s d = 1.17–4.56) were observed for discriminating between groups using MPE. Significant correlations were observed between the MPE and MoCA score (r = −0.670, p < 0.001) as well as between the MPE and dual task stride velocity (r = −0.584, p < 0.001). This study demonstrated feasibility and efficacy of estimating MPE from a practical wearable platform with promising results in identifying cognitive–motor impairment and potential application in assessing cognitive frailty. The proposed platform could be also used as an alternative to dual task walking test, where gait assessment may not be practical. Future studies need to confirm these observations in larger samples.

Development of EOG-Based Human Computer Interface (HCI) System Using Piecewise Linear Approximation (PLA) and Support Vector Regression (SVR)

Electrooculogram (EOG)-based human-computer interfaces (HCIs) are widely researched and considered to be a good HCI option for disabled people. However, conventional systems can only detect eye direction or blinking action. In this paper, we developed a bio-signal-based HCI that can quantitatively estimate the horizontal position of eyeball. A designed bio-signal acquisition system can measure EOG and temporalis electromyogram (EMG) signals simultaneously without additional electrodes. For real-time processing for practical application, modified sliding window algorithms are designed and applied for piecewise linear approximation (PLA). To find the eyeball position, support vector regression (SVR) is applied as a curve-fitting model. The average tracking error for target circle with a diameter of 3 cm showed only 1.4 cm difference on the screen with a width of 51 cm. A developed HCI system can perform operations similar to dragging and dropping used in a mouse interface in less than 5 s with only eyeball movement and bite action. Compare to conventional EOG-based HCI that detects the position of the eyeball only in 0 and 1 levels, a developed system can continuously track the eyeball position in less than 0.2 s. In addition, compared to conventional EOG-based HCI, the reduced number of electrodes can enhance the interface usability.

A Mathematical Proof Concerning the Geometrical Aspect of Very Low Index of Difficulty in Multidirectional Tapping Task of the ISO 9241 - Part 411

Through mathematics, this paper works to analyse the Index of Difficulty in ISO9241-Part 411: Evaluation methods for the design of physical input devices. It was proven that all the target circles always intersect for very low Index of Difficulty; which conjectured to disturb the experiment or affect the focus of the subject. Some examples are provided, in addition, to support the proof. We hope this proof will contribute to the improvement of ISO9241, where the result might become a special attention to the designer of the experiment in human-computer interaction field; especially in checking the influence of overlap area in the human factor.

Monocular vision for pose estimation in space based on cone projection

This paper presents a three-dimensional (3-D) pose estimation algorithm based on monocular vision. The algorithm relies on the circle target whose radius is known, with the scale condition given, the depth information of the circle can be recovered incompletely, and finally the pose of the target can be estimated by single projection only. First, the circle target was mapped to be an upright elliptic cone in the pinhole imaging model. Second, radius constraint was applied to recover partial depth of the circle target based on the upright elliptic cone. Experimental work concerning the validity and accuracy of this method is presented; furthermore, an application case for robot-aided positioning is introduced.

Accurate 3-D Surface Profilometry Using Novel Boundary Edge Detection on Digital Image Correlation

A novel 3-D edge detection methodology is developed to resolve the edge ambiguity problem encountered in 3-D optical surface profilometry employing digital image correlation (DIC). DIC has been surged as a full-field measurement technique for in-plane and out-of-plane dynamic mechanical structure analyses. However, up to date, one of the key issues in DIC is still remained in boundary edge detection since a surface edge is not detectable between two discrete neighboring height jumps due to optical diffraction. Generally, it is common to observe undesirable noisy measured data along surface edges in traditional DIC-based surface 3-D profilometry. To resolve this, a novel random speckle images processing method is established by proposing a new algorithm by employing the multiple symmetric partial template model to determine best edge location with accurate height reconstruction. A theoretical simulation on a pre-calibrated circle target was performed to verify the feasibility of the methodology. Some experiments on real industrial objects having various surface reflective characteristics were implemented to verify its capability on accurate detection of industrial objects having discrete surface edges. From its preliminary evaluation on measurement accuracy, it is found that the maximum measured error on critical dimension can be controlled within less than 6.0% of the overall measuring range while one standard deviation can be kept within less than 1.2%.

Attentional Dwelling and Capture by Color Singletons

Can salient stimuli—such as color singletons and abrupt onsets—involuntarily capture spatial attention? We previously reported evidence that abrupt onsets can capture attention, but the effects of this capture can become latent under easy visual search. The present experiments examined whether a similar pattern of latent capture occurs for task-irrelevant color singletons. Participants searched for a perfect circle among oval distractors. We manipulated search difficulty by varying the width of the oval distractors, making them more or less target-like (i.e., more or less circular). With search displays of homogeneous distractors, cue validity effects increased linearly with search difficulty, indicating capture by color singletons (Experiments 1 and 2). With heterogeneous distractors, however, discouraging the use of singleton-detection mode to find the target circle, cue validity effects from color singletons were negligible at all difficulty levels (Experiment 3). Using these exact same heterogeneous search displays, meanwhile, abrupt onsets produced very large cue validity effects (Experiment 4). We conclude that whereas abrupt onsets can capture attention based purely on salience, static color singletons capture attention only when made task-relevant by promoting singleton-detection mode (i.e., contingent capture). The data further support an attentional dwelling account of capture costs and reinforce the recommendation that, to ensure sensitivity to detect the presence (or absence) of attention capture, capture experiments should employ a difficult visual search.

Rapid Processing of a Global Feature in the ON Visual Pathways of Behaving Monkeys

Visual objects are recognized by their features. Whereas, some features are based on simple components (i.e., local features, such as orientation of line segments), some features are based on the whole object (i.e., global features, such as an object having a hole in it). Over the past five decades, behavioral, physiological, anatomical, and computational studies have established a general model of vision, which starts from extracting local features in the lower visual pathways followed by a feature integration process that extracts global features in the higher visual pathways. This local-to-global model is successful in providing a unified account for a vast sets of perception experiments, but it fails to account for a set of experiments showing human visual systems' superior sensitivity to global features. Understanding the neural mechanisms underlying the “global-first” process will offer critical insights into new models of vision. The goal of the present study was to establish a non-human primate model of rapid processing of global features for elucidating the neural mechanisms underlying differential processing of global and local features. Monkeys were trained to make a saccade to a target in the black background, which was different from the distractors (white circle) in color (e.g., red circle target), local features (e.g., white square target), a global feature (e.g., white ring with a hole target) or their combinations (e.g., red square target). Contrary to the predictions of the prevailing local-to-global model, we found that (1) detecting a distinction or a change in the global feature was faster than detecting a distinction or a change in color or local features; (2) detecting a distinction in color was facilitated by a distinction in the global feature, but not in the local features; and (3) detecting the hole was interfered by the local features of the hole (e.g., white ring with a squared hole). These results suggest that monkey ON visual systems have a subsystem that is more sensitive to distinctions in the global feature than local features. They also provide the behavioral constraints for identifying the underlying neural substrates.

Ebbinghaus figures that deceive the eye do not necessarily deceive the hand

In support of the visual stream dissociation hypothesis, which states that distinct visual streams serve vision-for-perception and vision-for-action, visual size illusions were reported over 20 years ago to ‘deceive the eye but not the hand’. Ever since, inconclusive results and contradictory interpretations have accumulated. Therefore, we investigated the effects of the Ebbinghaus figure on repetitive aiming movements with distinct dynamics. Participants performed a Fitts’ task in which Ebbinghaus figures served as targets. We systematically varied the three parameters which have been shown to influence the perceived size of the Ebbinghaus figure’s target circle, namely the size of the target, its distance to the context circles and the size of the context circles. This paper shows that movement is significantly affected by the context size, but, in contrast to perception, not by the other two parameters. This is especially prominent in the approach phase of the movement towards the target, regardless of the dynamics. To reconcile the findings, we argue that different informational variables are used for size perception and the visual control of movements irrespective of whether certain variables induce (perceptual) illusions.

心因性めまいと考えられた症例の重心動揺検査と視覚フィードバック検査の比較

The psychogenic vertigo has been diagnosed based on subjective dizzy symptom without abnormal findings of oculomotor tests and vestibular tests. We investigated the characteristics of the postural control system in patients with psychogenic vertigo using stabilometry and Body Tracking Tests with a visual feedback test to assess the dynamic body balance. This study consisted of 14 patients with psychogenic vertigo and 92 aged-match healthy subjects. They were instructed to keep the center of pressure constantly in the target circle displayed on the screen in front of the subjects. The dynamic body balance was evaluated by the proportion of the center of pressure (COP) including in the target circle during the test. The psychogenic vertigo group showed a larger area and a smaller locus length per unit area in comparison with the healthy subject group (p<0.01). In spectral analysis with the maximum entropy method (MEM), the power of the medio-lateral and antero-posterior positional power spectrum under eyes open condition were significantly largest at around 0.125 Hz in the psychogenic vertigo group. No significant difference in the result of Body Tracking Tests with a visual feedback test was found between both groups. Our results suggest that the patients with psychogenic vertigo maintain body balance with extremely slowly and large movements for quiet stance during eyes open condition. The results of Body Tracking Tests with a visual feedback test may indicate that the spontaneous postural control itself in patients with psychogenic vertigo does not differ from that in healthy individuals. We believe that this test could be useful as one of the significant diagnostic tests for psychogenic vertigo.

圆环标识的离心偏差校正方法与评价

圆环标识的离心偏差校正方法与评价

An improved method for location of concentric circles in vision measurement

Abstract Target with concentric circles has been widely used in camera calibration and vision measurement systems. An improved method to accurately locate the real projection of the concentric circles center has been proposed in this paper. Compared with similar methods, this method is computational efficiency and has no requirement of the concentric circles’ radii. Several simulations have been carried out to explore the influence of image noises, rotation angle, inner radius, outer radius and circle number to the center location accuracy, and several quantitative or semi-quantitative conclusions have been obtained, which can guide the optimum design of concentric circle target. Verification experiment was designed and result shows it is about 0.0891 pixel in accuracy and has promoted the computational efficiency scores of times. Moreover, a planar calibration target was designed and used to calibrate a binocular stereovision system, and test result shows the RMS error of the system has been improved to 0.0284 mm.