Visual Disparity Research Articles

Improvement of horizontal streak on disparity map thru parameter optimization for stereo vision algorithm

In this paper, an improved local based stereo vision disparity map (SVDM) algorithm is proposed. The proposed local based SVDM algorithm include four stages and they are matching cost computation, cost aggregation disparity optimization and disparity refinement. The matching cost computation started by combining pixel to pixel matching techniques, which are absolute difference (AD) and gradient matching (GM) in producing the initial disparity map. Next, the cost aggregation uses minimum spanning tree (MST) segmentation, which equipped with edge preserving properties and noise filtering. Then, disparity optimization uses local approach with winner-take-all (WTA) technique. At the final stage, disparity refinement uses bilateral filter (BF) with weighted median (WM), which can improve the disparity map through noise removing and edges preserving. Then, the research continues to optimize the proposed local based SVDM algorithm through parameters optimization in obtaining the final disparity map. Here, multiple parameters from the proposed SVDM algorithm are manipulated and they are constant values for GM and several constant parameters in BF. By selecting the optimum parameter values, the performance of the proposed SVDM algorithm increased, especially robustness towards the horizontal streaks.

Dynamics of Multimodal Components in English Educational Discourse: the Case of “English Grammar in Use” by Raymond Murphy

This article aims to identify the linguistic features of English-language educational discourse in terms of structural, descriptive, semantic, and cognitive-pragmatic analyses. The relevance of the study stems from the need to identify trends in the representation of language components in modern grammar textbooks within the communicative-pragmatic paradigm of educational discourse. The authors focus on the linguosynergetic potential of the English grammar textbook “English Grammar in Use” by Raymond Murphy, manifested in changes of certain discourse markers in all five editions. Employing a multimodal discourse analysis methodology, this research scrutinizes the verbal and visual disparities—encompassing graphic elements, letter capitalization, italics, font, and color—that hold pragmatic value and fulfill various roles, from engagement to information conveyance. The authors also investigate the interference of advertising and educational discourses and the small-format nature of texts in this self-study textbook, whose hypertext structure and internal navigational system serve as a surrogate for teacher guidance, thereby performing a directive function. A diachronic analysis of communicative scenarios within the textbook’s exercises reveals the dynamic utilization of interjections, underscoring their importance in creating an emotive-expressive backdrop that facilitates the acquisition of grammatical phenomena, reflective of their real-world application. Thus, in an attempt to represent the features of natural communication and to avoid the use of linguistic terms, the author of the textbook presents complex grammatical material in the most accessible form for a wide audience. Consequently, the study highlights the textbook’s increasing emphasis on the personality-bound component, complementing the traditionally dominant status-oriented approach in educational discourse.

Shell stand: Stable thin shell models for 3D fabrication

A thin shell model refers to a surface or structure, where the object’s thickness is considered negligible. In the context of 3D printing, thin shell models are characterized by having lightweight, hollow structures, and reduced material usage. Their versatility and visual appeal make them popular in various fields, such as cloth simulation, character skinning, and for thin-walled structures like leaves, paper, or metal sheets. Nevertheless, optimization of thin shell models without external support remains a challenge due to their minimal interior operational space. For the same reasons, hollowing methods are also unsuitable for this task. In fact, thin shell modulation methods are required to preserve the visual appearance of a two-sided surface which further constrain the problem space. In this paper, we introduce a new visual disparity metric tailored for shell models, integrating local details and global shape attributes in terms of visual perception. Our method modulates thin shell models using global deformations and local thickening while accounting for visual saliency, stability, and structural integrity. Thereby, thin shell models such as bas-reliefs, hollow shapes, and cloth can be stabilized to stand in arbitrary orientations, making them ideal for 3D printing.

Semantic image sorting method for RSVP presentation

Objective. The rapid serial visual presentation (RSVP) paradigm, which is based on the electroencephalogram (EEG) technology, is an effective approach for object detection. It aims to detect the event-related potentials (ERP) components evoked by target images for rapid identification. However, the object detection performance within this paradigm is affected by the visual disparity between adjacent images in a sequence. Currently, there is no objective metric to quantify this visual difference. Consequently, a reliable image sorting method is required to ensure the generation of a smooth sequence for effective presentation. Approach. In this paper, we propose a novel semantic image sorting method for sorting RSVP sequences, which aims at generating sequences that are perceptually smoother in terms of the human visual experience. Main results. We conducted a comparative analysis between our method and two existing methods for generating RSVP sequences using both qualitative and quantitative assessments. A qualitative evaluation revealed that the sequences generated by our method were smoother in subjective vision and were more effective in evoking stronger ERP components than those generated by the other two methods. Quantitatively, our method generated semantically smoother sequences than the other two methods. Furthermore, we employed four advanced approaches to classify single-trial EEG signals evoked by each of the three methods. The classification results of the EEG signals evoked by our method were superior to those of the other two methods. Significance. In summary, the results indicate that the proposed method can significantly enhance the object detection performance in RSVP-based sequences.

Rastall gravity: accretion disk image in the context of radiation fields and visual transformations compared to Reissner-Nordström black hole* *Supported by the National Natural Science Foundation of China (42230207), the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (G1323523064), and the Sichuan Youth Science and Technology Innovation Research Team (21CXTD0038)

In this study, we investigated the astronomical implications of Rastall gravity, particularly its behavior amidst a radiation field compared to Reissner-Nordström (RN) black holes. We found a crucial correlation between the dynamics of the accretion disk and the parameters Q and , which properly reflect the influence of spacetime metrics on the disk’s appearance. Elevated electric charge Q causes contraction in the disk’s orbit due to enhanced gravitational effects, while higher values lead to outward expansion, influenced by the attributes of the radiation field. Interestingly, the charged black holes surrounded by radiation fields exhibit distinct visual disparities from RN black holes. Brightness decreases and expansion occurs within the innermost stable circular orbit of the accretion disk with rising values. Our study also reveals the process by which the accretion disk transitions from a conventional disk-like structure to a hat-like form at different observation angles, with the redshift effect gradually intensifying. Moreover, the results of the considered Rastall gravity radiation field are consistent with the constraints of the gravitational lensing of the host galaxy on Rastall gravity parameters, thereby enhancing the consistency between theoretical predictions and actual observations.

Functional changes in fusional vergence-related brain areas and correlation with clinical features in intermittent exotropia using functional magnetic resonance imaging.

To explore the functional changes of the frontal eye field (FEF) and relevant brain regions and its role in the pathogenesis of intermittent exotropia (IXT) children via functional magnetic resonance imaging (fMRI). Twenty-four IXT children (mean age, 11.83 ± 1.93 years) and 28 normal control (NC) subjects (mean age, 11.11 ± 1.50 years) were recruited. During fMRI scans, the IXT children and NCs were provided with static visual stimuli (to evoke sensory fusion) and dynamic visual stimuli (to evoke motor fusion and vergence eye movements) with binocular disparity. Brain activation in the relevant brain regions and clinical characteristics were evaluated. Group differences of brain activation and brain-behavior correlations were investigated. For dynamic and static visual disparity relative to no visual disparity, reduced brain activation in the right FEF and right inferior occipital gyrus (IOG), and increased brain activation in the left middle temporal gyrus complex (MT+) were found in the IXT children compared with NCs. Significant positive correlations between the fusional vergence amplitude and the brain activation values were found in the right FEF, right IPL, and left cerebellum in the NC group. Positive correlations between brain activation values and Newcastle Control Scores (NCS) were found in the left MT+ in the IXT group. For dynamic visual disparity relative to static visual disparity, reduced brain activation in the right middle occipital gyrus, left cerebellum, and bilateral IPL was found in the IXT children compared with NCs. Significant positive correlations between brain activation values and the fusional vergence amplitude were found in the right FEF and right cerebellum in the NC group. Negative correlations between brain activation values and NCS were found in the right middle occipital gyrus, right cerebellum, left IPL, and right FEF in the IXT group. These results suggest that the reduced brain activation in the right FEF, left IPL, and cerebellum may play an important role in the pathogenesis of IXT by influencing fusional vergence function. While the increased brain activation in the left MT+ may compensate for this dysfunction in IXT children.

Multi-functional imaging inspired by insect stereopsis

Insects exhibit intriguing vision capability using fragmented information from arrays of lenses. Visual disparity between lenses or eyelets (also known as stereopsis) helps insects to locate their prey or find landing spots. Here we report a multi-functional imaging system inspired by insect stereopsis using a single ultrathin microlens array camera. Individual channels through tens of microlenses capture distinct images with visual disparities. We demonstrate that reconstruction of these images can provide diverse capabilities, such as simultaneous near-distance microscopic imaging, high speed imaging at far distances and 3D depth imaging at intermediate distances. Our findings offer clues to further understand the vision capability of insects as well as insights for advanced compact functional imaging tools.

Face-to-face learning enhances the social transmission of information.

Learning from others provides the foundation for culture and the advancement of knowledge. Learning a new visuospatial skill from others represents a specific challenge—overcoming differences in perspective so that we understand what someone is doing and why they are doing it. The “what” of visuospatial learning is thought to be easiest from a shared 0° first-person perspective and most difficult from a 180° third-person perspective. However, the visual disparity at 180° promotes face-to-face interaction, which may enhance learning by scaffolding social perspective taking, the “why” of visuospatial learning. We tested these potentially conflicting hypotheses in child and young adult learners. Thirty-six children (4–6 years) and 57 young adults (18–27 years) observed a live model open a puzzle box from a first-person (0°) or third-person (90° or 180°) perspective. The puzzle box had multiple solutions, only one of which was modelled, which allowed for the assessment of imitation and goal emulation. Participants had three attempts to open the puzzle box from the model’s perspective. While first-person (0°) observation increased imitation relative to a 180° third-person perspective, the 180° observers opened the puzzle box most readily (i.e., fastest). Although both age groups were excellent imitators and able to take the model’s perspective, adults were more faithful imitators, and children were more likely to innovate a new solution. A shared visual perspective increased imitation, but a shared mental perspective promoted goal achievement and the social transmission of innovation. "Perfection of means and confusion of goals—in my opinion—seem to characterize our age" Einstein (1973) pg 337, Ideas and Opinions

Proprioception-based movement goals support imitation and are disrupted in apraxia

The ability to imitate observed actions serves as an efficient method for learning novel movements and is specifically impaired (without concomitant gross motor impairments) in the neurological disorder of limb apraxia, a disorder common after left hemisphere stroke. Research with apraxic patients has advanced our understanding of how people imitate. However, the role of proprioception in imitation has been rarely assessed directly. Prior work has proposed that proprioceptively sensed body position is transformed into a visual format, supporting the attainment of a desired imitation goal represented visually (i.e., how the movement should look when performed). In contrast, we hypothesized a more direct role for proprioception: we suggest that movement goals are also represented proprioceptively (i.e., how a desired movement should feel when performed), and the ability to represent or access such proprioceptive goals is deficient in apraxia. Using a novel imitation task in which a robot cued meaningless trajectories proprioceptively or visually, we probed the role of each sensory modality. We found that patients with left hemisphere stroke were disproportionately worse than controls at imitating when cued proprioceptively versus visually. This proprioceptive versus visual disparity was associated with apraxia severity as assessed by a traditional imitation task, but could not be explained by general proprioceptive impairment or speed-accuracy trade-offs. These data suggest that successful imitation depends in part on the ability to represent movement goals in terms of how those movements should feel, and that deficits in this ability contribute to imitation impairments in patients with apraxia.

The Women Before Me: My Journey Painting Honor Wall Portraits of Women Physicians.

In this article, the authors briefly review the history and status of institutional honor wall portraits at medical schools, and they highlight the implications of a lack of diversity in these portraits for current medical students and the academic medicine pipeline. The authors then describe how contemporary portrait artists have used art as a tool for advocacy. They detail the first author's empowering and intimate journey as a medical student as she identified, connected with, and painted a portrait gallery of some of her medical school's prominent alumnae of color. This unique effort highlighted the unsung accomplishments of these women physicians and served to combat the visual disparity in honor wall portraits on campus. The authors also outline the common barriers faced by the portrait subjects and the key validation they offered the first author, a fellow woman of color. The authors describe the historical and psychological significance of several artistic decisions made for these portraits in weighing the intersections of race, gender, and profession. They then emphasize the reciprocal nature of oil portraiture and how, through painting these women, the first author was able to better envision her community of mentors, deepen her commitment to diversity and inclusion, and strengthen her own career aspirations. These portraits will hang in the student center of Harvard Medical School and will serve as a lasting reminder to future trainees, especially women and people of color, that they belong in the halls of medicine.

Sleep does not aid the generalisation of binocular disparity-based learning to the other visual hemifield.

Visual perceptual learning refers to long-lasting performance improvements on a visual skill - an ability supported by plastic changes in early visual brain areas. Visual perceptual learning has been shown to be induced by training and to benefit from consolidation during sleep, presumably via the reactivation of learning-associated neuronal firing patterns. However, previous studies have almost exclusively relied on a single paradigm, the texture discrimination task, on which performance improvements may rely on higher-order rather than lower-level perceptual skills. In the present study, we tested whether sleep has beneficial effects on a visual disparity discrimination task. We confirm previous findings in showing that the ability to discriminate different disparities is unaffected by sleep during a 12-hr retention period after training. Importantly, we extend these results by providing evidence against an effect of sleep on the generalisation of improved disparity discrimination across the vertical meridian. By relying on a between-subject design, we further exclude carry-over effects as a possible confound present in previous findings. These data argue against sleep as an important factor in the consolidation of a low-level perceptual skill. This sets important constraints on models of the role of sleep and sleep-associated neural reactivation in the consolidation of non-declarative memories.

When Visual Disparity Generation Meets Semantic Segmentation: A Mutual Encouragement Approach

Semantic segmentation and depth estimation play important roles in the field of autonomous driving. In recent years, the advantages of Convolutional Neural Networks (CNNs) have allowed these two topics to flourish. However, people always solve these two tasks separately and rarely solve them in a united model. In this paper, we propose a Mutual Encouragement Network (MENet), which includes a semantic segmentation branch and a disparity regression branch, and simultaneously generates semantic map and visual disparity. In the cost volume construction phase, the depth information is embedded in the semantic segmentation branch to increase contextual understanding. Similarly, the semantic information is also included in the disparity regression branch to generate more accurate disparity. Two branches mutually promote each other during training phase and inference phase. We conducted our method on the popular dataset KITTI, and the experimental results show that our method can outperform the state-of-the-art methods on both visual disparity generation and semantic segmentation. In addition, extensive ablation studies also demonstrate that the two tasks in our method can facilitate each other significantly with the proposed approach.

Optokinetic stimulation induces vertical vergence, possibly through a non-visual pathway

Vertical vergence is generally associated with one of three mechanisms: vestibular activation during a head tilt, induced by vertical visual disparity, or as a by-product of ocular torsion. However, vertical vergence can also be induced by seemingly unrelated visual conditions, such as optokinetic rotations. This study aims to investigate the effect of vision on this latter form of vertical vergence. Eight subjects (4m/4f) viewed a visual scene in head erect position in two different viewing conditions (monocular and binocular). The scene, containing white lines angled at 45° against a black background, was projected at an eye-screen distance of 2 m, and rotated 28° at an acceleration of 56°/s2. Eye movements were recorded using a Chronos Eye-Tracker, and eye occlusions were carried out by placing an infrared-translucent cover in front of the left eye during monocular viewing. Results revealed vergence amplitudes during binocular viewing to be significantly lower than those seen for monocular conditions (p = 0.003), while torsion remained unaffected. This indicates that vertical vergence to optokinetic stimulation, though visually induced, is visually suppressed during binocular viewing. Considering that vertical vergence is generally viewed as a vestibular signal, the findings may reflect a visually induced activation of a vestibular pathway.

A Ship Ranging and Positioning System Based on Binocular Vision Technology

Relative ranging and positioning is the basis to ensure the navigation safety of ships, and it has a broad application prospect in various maritime activities, especially in the aspects of docking and undocking, sailing in crowded areas, towing, convoy sailing, and warship replenishment, etc. In order to improve the autonomy and automation of ship ranging and positioning and reduce the cost, a novel type of ship ranging and positioning system based on binocular vision technology is proposed. The proposed system includes seven modules, i.e. video information acquisition module, ship attitude acquisition module, camera parameter calibration module, target recognition and segmentation module, image matching module, ranging and positioning module, and information display module. After acquiring the target image sequences by using two cameras, the proposed system identifies and segments maritime targets quickly by using Canny algorithm in the artificial interactive mode, realizes reduced-space search by using epipolar constraint method, achieve fast target features matching to obtain the vision disparity of the feature points by using the SURF algorithm, and calculates the distance of the target according to the binocular vision ranging principle, so as to realize interactive visual ranging and positioning. The proposed system has the advantages of low cost, simple structure and convenient operation. It can realize relative ranging and positioning with only one computer and two cameras. Experiments demonstrate that the proposed system, with fast running speed and high accuracy, can satisfy the relative ranging and positioning needs of ships.

Fabricable Unobtrusive 3D‐QR‐Codes with Directional Light

AbstractQR code is a 2D matrix barcode widely used for product tracking, identification, document management and general marketing. Recently, there have been various attempts to utilize QR codes in 3D manufacturing by carving QR codes on the surface of the printed 3D shape. Nevertheless, significant shape editing and modulation may be required to allow readability of the embedded 3D‐QR‐codes with good decoding accuracy. In this paper, we introduce a novel QR code 3D fabrication framework aimed at unobtrusive embedding of 3D‐QR‐codes in the shape hence introducing minimal shape modulation. Essentially, our method computes bi‐directional carvings in the 3D shape surface to obtain the black‐and‐white QR pattern. By using a directional light source, the black‐and‐white QR pattern emerges as lighted and shadow casted blocks on the shape respectively. To account for minimal modulation and elusiveness, we optimize the QR code carving w.r.t. shape geometry, visual disparity and light source position. Our technique employs a simulation of lighting phenomena through carved modules on the shape to ensure adequate contrast of the printed 3D‐QR‐code.

Robust registration for ultra-field infrared and visible binocular images.

The ultra-field infrared and visible image registration is a challenging task due to its nonlinear imaging and multi-modal image features. In this paper, a robust registration method is proposed for the ultra-field infrared and visible images. First, control points are extracted utilizing phase congruency and optimized based on the guidance map, which is proposed according to significant structures information. Second, ROI pair matching is accomplished based on epipolar curve. Its effect is equivalent to a search window that is popular in methods with the standard field of view, and it can overcome the content differences in the search window caused by nonlinear imaging and vision disparity. Third, a descriptor, named multiple phase congruency directional pattern (MPCDP), is established and composed of distribution information and main direction. The phase congruency amplitudes are encoded as binary patterns, and then they are represented as weighted histogram for distribution information. Six pairs of ultra-field infrared and visible images are employed for registration experiments, and the results demonstrate that the performance of the proposed is robust and accurate in five types of ultra-field scenes and two different camera relationships.

Reflections of Science and Medicine in Two Frankenstein Adaptations: Frankenstein (Whale 1931) and Mary Shelley’s Frankenstein (Branagh 1994)

That the history of science and the genre of science fiction are complexly interwoven is illustrated by Mary Shelley’s Frankenstein, a novel that primarily reflected contemporaneous scientific interest in the reanimation of corpses by galvanism. The science/science fiction relationship is further extended by analyzing the visual differences in two film adaptations of Shelley’s novel. The first, directed by James Whale, presents Shelley’s Creature as a robotic figure, suggesting automation as an influencing theme and electricity as a source of life. Contrastingly, the Creature of Kenneth Branagh’s 1994 adaptation is corporeal and abject. While neither version takes account of obvious medical implausibilities, each reveals how discourses of science and medical history have shifted since Shelley wrote her novel. This essay argues that the visual disparity between the two film adaptations in comparison to the source text not only discloses a visual chronicle of science but also a history of technological progress.

QUALITAS: Image Quality Assessment for Stereoscopic Images

In this article, the authors present a method for assessing image quality in stereoscopic images: QUALITAS. The proposed method is inspired by some features of the human visual system, such as contrast sensitivity, response to visual disparity and perception of distance. Individual qualities of the stereo-pair are not simply averaged. QUALITAS introduces Contrast Band-Pass Filtering on a wavelet domain in both views; in this way it weights left and right images perceptually depending on viewing conditions. The authors have tested the method on the LIVE 3D stereoscopic image database and compared the results with a wide set of image quality metrics from current research.

Stereo Vision System Implemented on FPGA

Stereo vision systems are computer vision implementations that use stereoscopic ranging techniques to estimate a 3D model of a scene. Stereo vision employs triangulation, a popular ranging technique, to compute the depth from 2D images. The theoretical background and geometry that associates visual disparity to scene structure is obvious; however, the procedure to automatically compute disparity by inter-image correspondence in real-time is challenging. This paper proposes a stereo vision system that provides dense depth maps in real-time from monochrome cameras. The entire process is realized in a single field programmable gate array (FPGA). FPGAs, being inherently parallel in nature, are quite suitable for the problem and are found to be much faster for such computer vision applications from previous studies.

Literature Survey on Stereo Vision Disparity Map Algorithms

This paper presents a literature survey on existing disparity map algorithms. It focuses on four main stages of processing as proposed by Scharstein and Szeliski in a taxonomy and evaluation of dense two-frame stereo correspondence algorithms performed in 2002. To assist future researchers in developing their own stereo matching algorithms, a summary of the existing algorithms developed for every stage of processing is also provided. The survey also notes the implementation of previous software-based and hardware-based algorithms. Generally, the main processing module for a software-based implementation uses only a central processing unit. By contrast, a hardware-based implementation requires one or more additional processors for its processing module, such as graphical processing unit or a field programmable gate array. This literature survey also presents a method of qualitative measurement that is widely used by researchers in the area of stereo vision disparity mappings.