Binocular System Research Articles

68‐1: Investigation on Defocusing‐Induced Accommodation Shift in Microlens Array‐Based Near‐Eye Light Field Displays

The accommodation response in a microlens array‐based near‐eye light field display is found to considerably shift towards the central depth plane but not at the reconstructed depth plane due to defocusing of the lens array. The shifts are characterized and can be fully addressed by compensating in a binocular system.

Application of binocular visual navigation technique in diaphyseal fracture reduction.

Computer-assisted surgical navigation techniques have shown promise; however, currently popular systems have limitations. This paper presents the characterization and application of a binocular visual navigation technique in diaphyseal fracture reduction. A binocular visual tracker (MicronTracker) was introduced to reduce diaphyseal fractures. A transformation matrix was used to acquire the reduction parameters. A transverse diaphyseal fracture was used as a control group. Precision tests were performed with the binocular system using a simulation femoral model with a transverse fracture 12 times. All residual deformations were compared and P < 0.01. The binocular visual navigation technique produces good results with advantages of flexibility and high positional accuracy and shows promise. The MicronTracker might lead to further application in the remote navigation field.

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

Revisiting the influence of accommodation and accommodation disorders on the process of development and progression of myopia (literature review)

Purpose. To analyze domestic and foreign scientific publications over the past 5 years, reflecting the issues of accommodation and accommodation disorders. To assess the presence or absence of changes in the classification of accommodation disorders. To evaluate the role of various accommodation disorders in the development and progression of myopia. Relevance. Given the significant increase in the number of people with myopia in recent decades, interest in the study of accommodation and accommodation disorders has increased again. This is due not only to the fact that accommodative insufficiency (AI, weak accommodation), is considered one of the leading factors in the development of myopia, but also because the use of one or another method of myopia control affects the process of accommodation, increasing or reducing accommodation reserves, affecting the functioning of the binocular system. New developments in the field of visualization of intraocular structures (anterior segment imaging by OCT, Sheimpflug imaging, UBM) allows carry out previously impossible studies of changes in the crystalline lens, ciliary body, at different levels of accommodation response, in different age groups in vivo, which itself affects the development and testing of new concepts related to the mechanism of the accommodation. Thus, the dynamics of the changes that are taking place motivates ophthalmologists to take a fresh look at the already established concepts of the accommodation mechanism, to assess the consistency of previously adopted approaches to the classification of accommodation disorders, which in turn can affect changes in the tactics of myopia control, which is especially crucial as myopization of the population, especially in children, is accelerating every day. Our task was to evaluate domestic and foreign scientific publications over the past 5 years, reflecting the results of studies of the accommodation mechanism, assessing the influence of accommodation disorders on the progression of myopia. The task was also to assess the prospect of creating a unified classification of accommodative disturbances, the ability to create a unified algorithm for controlling progression, based on accommodation parameters. Search strategy. A review of English and Russian sources related to the study of the mechanism of accommodation was conducted; the effect of accommodation disorders on the progression of myopia and their classification was studied using the following databases: PubMed, Cyberleninka, Google scholar, Elibrary. The search depth was 5 years (2014-2019), excluding the historical sources. The sources included: - original research; - historical issue, scanned publications; - studies / descriptions of accommodation disorders and their relationship with myopia; - abstracts and full-text publications; - literary reviews; - monographies. The exclusion criteria were: - themed issues with closed or restricted access. During the process of searching and processing information, the data obtained were not systematized according to the level of reliability due to the fact that the purpose of the review is to obtain a general idea of the views on this issue, assess the presence or absence of unity in the formation of diagnostic criteria, without the task of suggesting practical recommendations. The following search queries were made to search the databases: a) English-language sources - mechanism of accommodation, accommodation AND history issue, accommodation AND Helmholtz AND Tsherning, accommodation AND myopia, accommodation AND myopia control AND myopia progression, accommodation disorders OR accommodation anomalies, accommodative excess AND accommodative infacility AND accommodative insufficiency, epidemiology myopia AND etiology myopia, near work AND myopia AND children; b) Russian-language sources - the history of the study of accommodation, the mechanism of accommodation, classification of accommodation disorders, accommodation, accommodation disorders with myopia, accommodation and the progression of myopia, weakness of accommodation, habitual excess tension of accommodation; progressive myopia, myopia control.

Visual Locating of Reactor in an Industrial Environment Using the Composite Method.

To achieve an automatic unloading of a reactor during the sherardizing process, it is necessary to calculate the pose and position of the reactors in an industrial environment with various amounts of luminance and floating dust. In this study, the defects of classic image processing methods and deep learning methods used for locating the reactors are first analyzed. Next, an improved You Only Look Once(YOLO) model is employed to find the region of interest of the handling hole and a handling hole corner detection method based on the image morphology and a Hough transform is presented. Finally, the position and pose of the reactors will be obtained by establishing a 3D handling hole model according to the principle of a binocular stereo system. To test the performance of the proposed method, a set of experimental systems was set up and experiments were conducted. The results indicate that the proposed location method is effective and the precision of the position recognition can be controlled to within 4.64 mm and when the cameras are approximately 5 m away from the reactor, meeting the requirements.

A Real-Time Multilevel Fusion Recognition System for Coal and Gangue Based on Near-Infrared Sensing

Coal is an indispensable energy source for humans. As an important part of the mining industry, intelligent separation of coal and gangue will promote development. The traditional methods of recognition do not consider the interference created by a dynamic environment. There are many problems such as noise, complex backgrounds and occlusion, which lead to low accuracy and cannot satisfy real-time requirements in mining. Aiming at dynamic environments, a real-time multilevel fusion recognition system was built in this paper. First, we introduced a near-infrared camera into the field of separation, which was used to form a binocular system with a visible light camera. The SVM classifier was obtained by feature selection and fusion training of the binocular system, which overcomes the interference of environmental factors. Then, we proposed a new deep learning training method of two-sample fusion to improve the recognition network performance by expanding the number of samples and features. Finally, the SVM and deep learning algorithms were combined to establish a fast detection strategy. In addition, the length suppression algorithm was added to solve the occlusion problem. The accuracy of the fusion algorithm was 0.923 and the detection speed was increased to 26 fps. The experimental results indicated that the sorting system satisfied the requirements of real-time and robust of the coal industry.

Neuronal Specialization for Fine-Grained Distance Estimation Using a Real-Time Bio-Inspired Stereo Vision System

The human binocular system performs very complex operations in real-time tasks thanks to neuronal specialization and several specialized processing layers. For a classic computer vision system, being able to perform the same operation requires high computational costs that, in many cases, causes it to not work in real time: this is the case regarding distance estimation. This work details the functionality of the biological processing system, as well as the neuromorphic engineering research branch—the main purpose of which is to mimic neuronal processing. A distance estimation system based on the calculation of the binocular disparities with specialized neuron populations is developed. This system is characterized by several tests and executed in a real-time environment. The response of the system proves the similarity between it and human binocular processing. Further, the results show that the implemented system can work in a real-time environment, with a distance estimation error of 15% (8% for the characterization tests).

Effect of Catadioptric Component Postposition on Lens Focal Length and Imaging Surface in a Mirror Binocular System.

The binocular vision system is widely used in three-dimensional measurement, drone navigation, and many other fields. However, due to the high cost, large volume, and inconvenient operation of the two-camera system, it is difficult to meet the weight and load requirements of the UAV system. Therefore, the study of mirror binocular with single camera was carried out. Existing mirror binocular systems place the catadioptric components in front of the lens, which makes the volume of measurement system still large. In this paper, a catadioptric postposition system is designed, which places the prism behind the lens to achieve mirror binocular imaging. The influence of the post prism on the focal length and imaging surface of the optical system is analyzed. The feasibility of post-mirror binocular imaging are verified by experiments, and it is reasonable to compensate the focal length change by changing the back focal plane position. This research laid the foundation for the subsequent research on the 3D reconstruction of the novel mirror binocular system.

Automated visual positioning and precision placement of a workpiece using deep learning

An automated visual positioning system is proposed for precision placement of a workpiece on the fixture. The system includes a binocular eye-in-hand system on the end effector of the mobile manipulator and a ConvNet for detecting the relative position of the workpiece based on the holistic views observed by the CMOS cameras. We train the ConvNets with training images that are automatically generated from basis images taken at the target position and annotated with the 2D coordinates of the offset locations. The ConvNet’s superior place recognition capability renders a high success rate of coordinate detection subject to high illumination and viewpoint variations. Experimental evidence of workpiece placement confirms that the low-resolution (640 × 480 pixels) camera can obtain a translational precision of ±0.2 mm; the binocular system can control the rotational error within ± 0.1°. Within the 20 × 20-mm2 spatial tolerance of the mobile platform, the proposed system achieves a success rate of 100% in 200 workpiece placement tasks. The entire workpiece placement task can be completed in 60 s; the average elapsed time of precision positioning and placement is less than 20 s, with a total of 4 visual positioning steps.

Visual system disorders and musculoskeletal neck complaints: a systematic review and meta-analysis.

Accommodation disorders and nonstrabismic binocular dysfunctions affect patients' binocular system and visual performance. These visual disorders could be associated with musculoskeletal discomfort in the neck and shoulder area. The purpose of this systematic review and meta-analysis was to ascertain the relationship between visual system disorders and the musculoskeletal system of the neck. The review protocol is available in PROSPERO (CRD42018112771). All articles selected examined the relationship between neck conditions (chronic neck pain and whiplash) and the visual system in adult populations. Studies with optometric or physiotherapeutic measurements were included. Bias risk was evaluated with the modified Cochrane Collaboration Tool and Study Quality Assessment Tool. To provide complete quality assessment evidence, the authors applied the GRADEpro Guideline Development Tool. The literature search was conducted in November 2018 and yielded 745 studies among all the databases. Out of these studies, 21 were finally included. Most of the studies presented a moderate methodological quality. Only one high-quality trial was found. Based on a qualitative assessment, our systematic review and meta-analysis revealed that all included studies established a relationship between the visual system and musculoskeletal system of the neck. However, the methods for the measurement of the visual system lacked uniformity.

Depth recovery for unstructured farmland road image using an improved SIFT algorithm

Road visual navigation relies on accurate road models. This study was aimed at proposing an improved scale-invariant feature transform (SIFT) algorithm for recovering depth information from farmland road images, which would provide a reliable path for visual navigation. The mean image of pixel value in five channels (R, G, B, S and V) were treated as the inspected image and the feature points of the inspected image were extracted by the Canny algorithm, for achieving precise location of the feature points and ensuring the uniformity and density of the feature points. The mean value of the pixels in 5×5 neighborhood around the feature point at an interval of 45o in eight directions was then treated as the feature vector, and the differences of the feature vectors were calculated for preliminary matching of the left and right image feature points. In order to achieve the depth information of farmland road images, the energy method of feature points was used for eliminating the mismatched points. Experiments with a binocular stereo vision system were conducted and the results showed that the matching accuracy and time consuming for depth recovery when using the improved SIFT algorithm were 96.48% and 5.6 s, respectively, with the accuracy for depth recovery of –7.17%-2.97% in a certain sight distance. The mean uniformity, time consuming and matching accuracy for all the 60 images under various climates and road conditions were 50%-70%, 5.0-6.5 s, and higher than 88%, respectively, indicating that performance for achieving the feature points (e.g., uniformity, matching accuracy, and algorithm real-time) of the improved SIFT algorithm were superior to that of conventional SIFT algorithm. This study provides an important reference for navigation technology of agricultural equipment based on machine vision. Keywords: scale-invariant feature transform (sift), feature matching, canny operator, energy method of feature point, farmland road, depth recovery, visual navigation DOI: 10.25165/j.ijabe.20191204.4821 Citation: Yao L J, Hu D, Yang Z D, Li H B, Qian M B. Depth recovery for unstructured farmland road image using an improved SIFT algorithm. Int J Agric & Biol Eng, 2019; 12(4): 141–147.

Vision Performance and Accommodative/Binocular Function in Children Wearing Prototype Extended Depth-of-Focus Contact Lenses.

To assess two prototype contact lenses (CLs) that extend depth of focus through deliberate manipulation of multiple spherical aberration terms (extended depth-of-focus [EDOF]) for visual performance, accommodative and binocular function, and objective static near refraction against a single-vision (SV) CL. This was a prospective, randomized, cross-over, single-masked (participant) clinical trial in which 16 myopic children wore 2 prototype CLs (EDOFL/EDOFH) designed for presbyopes and a SV CL, each for one week. Measurements comprised monocular and binocular high-contrast visual acuity (HCVA: 6 m, 40 cm), binocular low-contrast visual acuity (LCVA: 6 m), contrast sensitivity (CS: 6 m), phorias (3 m, 33 cm), monocular-accommodative facility (33 cm), and objective static refraction (spherical equivalent M) at zero, -3, and -5 D vergences. Measurements were taken 10 min after lens insertion. Subjective response was assessed using take-home questionnaires comprising vision clarity (distance/intermediate/near), vision quality (haloes at night/ghosting), vision stability when moving (playing sport/using stairs), and comfort. Single vision was significantly better than both EDOF CLs for monocular HCVA, LCVA, and CS (6 m); vision clarity (distance), ghosting (P≤0.040), and EDOFL for binocular HCVA (6 m, P=0.047). M was significantly closer to the ideal objective static refraction at -3 and -5 D vergences (P≤0.004) with both EDOF compared with SV CLs. There were no differences between CLs for any other variable (P≥0.169). Extended depth-of-focus CLs caused minimal disruption to the accommodative and binocular system compared with SV CLs when worn by myopic children. Future EDOF designs for children should reduce the difference between SV for distance vision and vision quality while maintaining the same performance for intermediate and near.

Binocular system with asymmetric eyes: erratum.

Corrections are given for misprints in J. Opt. Soc. Am. A35, 1180 (2018)JOAOD60740-323210.1364/JOSAA.35.001180.

Holographic Three-Dimensional Virtual Reality and Augmented Reality Display Based on 4K-Spatial Light Modulators

In this paper, we propose a holographic three-dimensional (3D) head-mounted display based on 4K-spatial light modulators (SLMs). This work is to overcome the limitation of stereoscopic 3D virtual reality and augmented reality head-mounted display. We build and compare two systems using 2K and 4K SLMs with pixel pitches 8.1 μm and 3.74 μm, respectively. One is a monocular system for each eye, and the other is a binocular system using two tiled SLMs for two eyes. The viewing angle of the holographic head-mounted 3D display is enlarged from 3.8 ∘ to 16.4 ∘ by SLM tiling, which demonstrates potential applications of true 3D displays in virtual reality and augmented reality.

A Remote Free-Head Pupillometry Based on Deep Learning and Binocular System

Objective: Pupillometer plays a key role in a variety of research areas, including disease diagnosis, human-machine interaction, and education. Here, we set out to leverage the deep learning theory to develop a remote binocular vision system for pupil diameter estimation. Approach: the system consists of three parts: eye detection, eye tracking, and pupil diameter estimation. We first train a convolutional neural network based on YOLO V2 to perform eye detection, leading to high accuracy and robustness under ambient light interference. By exploring the similarity of binocular camera images, we then propose a master–slave structure for eye tracking, surpassing the traditional parallel structure in tracking speed while keeping considerable accuracy. Furthermore, we develop a pupil diameter estimation algorithm based on binocular vision, avoiding the personal calibration procedure and reducing the measurement distortion error. Main results: Experimental results on real datasets reveal that our system exhibits the state-of-the-art performance with high eye detection accuracy (90.6%), fast eye tracking speed (<11 ms per frame), low pupil diameter estimation error [(0.022±0.017) mm mean absolute error, and (0.6 ± 0.7)% percentage of the mean absolute error] and excellent flexibility. Significance: in contrast with previous pupillometers, which lead to pupil diameter measurement distortion error through a 2-D projection image on a single camera, our system measures pupil diameter in 3-D space without distortion influence, thus improving its robustness to head angle variation and making it more practical for real applications.

Astigmatism correction for distance and near vision

The clarity of the retinal image decreases as a result of non-corrected astigmatism. It contributes to the deterioration of the quality of vision and to a blurred vision. Thus, a clear vision can be achieved neither at distance nor when looking at nearby objects. Such blurry vision leads to asthenopia, headache, migraine, decreased reading speed and finally can become a cause of learning difficulties for a child or a student. In order to avoid such difficulties, there is a need to correct even a low degree of astigmatism and thus create the conditions under which the binocular system could work properly. First of all, we are talking about the correlation between accommodation, convergence and heterophoria, which should all work in cooperation. Only in conditions of emmetropia, i.e. single focus on the retina, the binocular system can work correctly, reducing symptoms and visual overload.

An industrial light field camera applied for 3D velocity measurements in flow past confined cylinder

Light field cameras have some advantages over classic cameras in a narrow field of application, such photography, cinematography surveillance and quality control in industry. Light field cameras have larger depth of field, compare to regular camera, but lower spatial resolution along optical axis then binocular system. However, 3D velocity measurements using light field are reasonable alternative to modern 3D PIV measurements. The nature of light field image requires extra reconstruction step which affects overall accuracy. In this article, light field PTV was compared to Tomo-PIV. Both techniques were used to measure 3D velocity fields in a turbulent wake past confined cylinder.

改进的尺度不变特征变换算法并行加速双目测距系统及其实现

改进的尺度不变特征变换算法并行加速双目测距系统及其实现

Foreign object recognition technology for port transportation channel based on automatic image recognition

In the port transportation, the transportation vehicle is extremely easy to cause a bad condition in the transportation process due to the influence of foreign matter, and the current foreign matter detection is still carried out by manual methods. Based on this, this study is based on the automatic image recognition technology, using the binocular imaging system for video collection and analyzing the video images for foreign object recognition. We use extreme median filtering to perform image noise processing and improve the traditional Canny edge detection algorithm to obtain an improved edge detection method for Canny operator. The algorithm is used to perform image edge detection, and the image gray histogram is used to enhance the foreign object image processing. Combined with the experimental analysis, the detection method of this study has certain effects, which can be used for foreign object identification in port transportation channels and can provide theoretical reference for subsequent related research.

Correction: Simple reaction times to cyclopean stimuli reveal that the binocular system is tuned to react faster to near than to far objects.

[This corrects the article DOI: 10.1371/journal.pone.0188895.].