Monocular Mode Research Articles

Visual SLAM system based on dynamic semantic features

Aiming at the problem that dynamic objects (such as pedestrians, vehicles, and animals) in real scenes affect the positioning and mapping accuracy of visual SLAM (Simultaneous Localization and Mapping), a YOLOv3-ORB-SLAM3 algorithm is proposed based on ORB-SLAM3 (Oriented FAST and Rotated BRIEF-Simultaneous Localization and Mapping 3). The algorithm adds a semantic thread on the basis of ORB-SLAM3, and adopts a dual-thread mechanism for dynamic and static scene feature extraction: the semantic thread uses YOLOv3 to perform semantic recognition target detection on dynamic objects in the scene, and removes outliers from the extracted dynamic area feature points; the tracking thread extracts scene area features through ORB features, and obtains static scene features combined with semantic information and sends them to the backend, thereby eliminating the interference of dynamic scenes on the system and improving the positioning accuracy of the visual SLAM algorithm. Verified using the TUM (Technical University of Munich) dataset, the results show that the ATE (Average Treatment Effect) index of the YOLOv3-ORB-SLAM3 algorithm in the monocular mode is about 30% lower than that of the ORB-SLAM3 algorithm, and the ATE index of the dynamic sequence in the RGB-D (Red, Green and Blue-Depth) mode is reduced 10%, while the static sequence has no significant decrease.

Frame Loss Effects on Visual Fatigue in Super Multi-View 3D Display Technology

Super multi-view (SMV) display is a promising 3D display technology; however, potential frame loss due to bandwidth-limited video transmission could cause discomfort to viewers. Thus, an evaluation of the acceptable viewing experience will be valuable. This study investigates the effects of frame loss on visual fatigue in SMV display, focusing on quantified frame loss rates and varying frame loss modes. Experiments were conducted with 20 subjects, utilizing the Stroop test through an SMV display system to evaluate the visual fatigue under different frame loss conditions. The results show a rise in visual fatigue as the frame loss rate increases, with two critical thresholds identified. A 4% frame loss rate marks the threshold for significant loss-induced differences, beyond which visual fatigue begins to become significant in loss-induced modes compared to the normal loss-free mode. Subsequently, a 10% frame loss rate marks the threshold for significant mode-dependent differences, beyond which variations appear between different loss-induced modes, with monocular mode inducing more visual fatigue than binocular and dual-view more than single-view. Consequently, the findings advocate for refining the 3D video processing to maintain a frame loss rate below 4% for negligible effect and considering the interactions between different views for less visual fatigue. This research aims to provide insights and guidance for addressing potential challenges in developing and applying SMV display technology.

The energy spectrum of cosmic rays measured by the Telescope Array using 10 years of fluorescence detector data

The Telescope Array (TA) Cosmic Ray Observatory is the largest cosmic ray detector in the northern hemisphere. TA was built to study ultra-high-energy cosmic rays (UHECRs), cosmic rays with energies above 1018eV. TA is a hybrid detector, employing two distinct detection methods: a surface detector array and a set of fluorescence telescopes. We will present a measurement of the cosmic ray energy spectrum for energies above 1017.5eV using only the fluorescence telescopes. A novel weather classification scheme using machine learning was used to select data parts with good weather to ensure the quality of the fluorescence data. The data from the Black Rock Mesa (BRM) and Long Ridge (LR) fluorescence telescope sites were analyzed separately in monocular mode, with the calculated fluxes combined into a single spectrum. The 10-year monocular combined cosmic ray energy spectrum is observed to be in excellent agreement with previous measurements from the northern hemisphere. We present fits of the combined spectrum to a series of broken power law models. The thrice-broken power law was observed to be the best fit considering the Poisson deviance per degrees of freedom. The three breaks suggest an additional feature of the spectrum between the previously observed Ankle feature at 1018.7eV and the GZK suppression at 1019.8eV.

The Cosmic-Ray Composition between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode

Abstract We report on a measurement of the cosmic-ray composition by the Telescope Array Low-energy Extension (TALE) air fluorescence detector (FD). By making use of the Cherenkov light signal in addition to air fluorescence light from cosmic-ray (CR)-induced extensive air showers, the TALE FD can measure the properties of the cosmic rays with energies as low as ∼2 PeV and exceeding 1 EeV. In this paper, we present results on the measurement of distributions of showers observed over this energy range. Data collected over a period of ∼4 yr were analyzed for this study. The resulting distributions are compared to the Monte Carlo (MC) simulated data distributions for primary cosmic rays with varying composition and a four-component fit is performed. The comparison and fit are performed for energy bins, of width 0.1 or 0.2 in , spanning the full range of the measured energies. We also examine the mean value as a function of energy for cosmic rays with energies greater than 1015.8 eV. Below 1017.3 eV, the slope of the mean as a function of energy (the elongation rate) for the data is significantly smaller than that of all elements in the models, indicating that the composition is becoming heavier with energy in this energy range. This is consistent with a rigidity-dependent cutoff of events from Galactic sources. Finally, an increase in the elongation rate is observed at energies just above 1017 eV, indicating another change in the cosmic-ray composition.

Application of the Virtual Reality-Pattern Visual Evoked Potential in Forensic Visual Acuity Evaluation

Objective To explore a kind of visual evoked potential test equipment and method that is more suitable for the application of forensic clinical visual acuity evaluation. Methods Thirty-four volunteers （68 eyes） were selected, including 15 males and 19 females, aged between 20 and 40 years. Test lenses were placed before the tested eyes of volunteers to induce refractive myopia with insert method, and the diopter lenses were adjusted so that the visual acuity level of one eye of volunteers was above 0.8, and the visual acuity of the other eye was at moderate damage level （<0.3 and ≥0.1）. The tests were carried out under the binocular simultaneous asynchronous stimulation mode （hereinafter referred to as "binocular mode"） and monocular separate stimulation mode （hereinafter referred to as "monocular mode"） of virtual reality-pattern visual evoked potential （VR-PVEP）, and the amplitude of PVEP of volunteers under the two modes was compared at four spatial frequencies of 8×8, 16×16, 24×24 and 32×32. Results The differences in the amplitude of P100 wave between monocular and binocular modes at 8×8 spatial frequency had no statistical significance and the differences in amplitude of P100 wave between monocular and binocular modes at 16×16, 24×24, and 32×32 spatial frequencies had statistical significance （P<0.05）. The amplitude of the same eye in monocular mode was higher than that in binocular mode. Through correlation analysis, it was found that the amplitude of P100 wave in monocular mode was moderately correlated with amplitude of P100 wave in binocular mode. Conclusion In forensic identification practice, VR-PVEP is helpful for overcoming the disturbance of poor fixation, and to increase the reliability of PVEP evaluation results. It can greatly shorten the detection time of PVEP and improve work efficiency.

One Year Outcome and Satisfaction of Presbyopia Correction Using the PresbyMAX® Monocular Ablation Profile

Purpose: To explore the safety, efficacy, and satisfaction of the PresbyMAX monocular mode for the correction of presbyopia.Methods: Prospective study. Twenty-two patients (mean age 50.6 ± 6.2 years, 11 myopia patients and 11 hyperopia patients) were enrolled. The dominant eye was fully corrected for distance vision; the non-dominant eye was corrected using central PresbyMAX monocular mode. Binocular uncorrected distance visual acuity (BUDVA), near visual acuity (BUNVA), intermediate visual acuity (BUIVA), corrected distance visual acuity (CDVA), and mean spherical equivalent (SE) were tested at 1 day, 1 week, 1 month, 3 months, and 1 year postoperatively. Questionnaire was performed preoperatively, 1 month, 3 months, and 1 year after surgery.Results: At the final visit, the mean safety index was 1.03 ± 0.14. There were 85.7% eyes with the same or better CDVA than the preoperative value, and 17.1% and 2.9% eyes gained 1 line and 2 lines of CDVA, respectively. All treated eyes achieved 20/25 or better BUDVA, and 95.5% achieved 20/32 or better BUNVA, which improved significantly compared with preoperative values (P < 0.001). BUDVA maintained stability from 1 month postoperatively, BUNVA and BUIVA kept stable since 1 week after surgery. Overall satisfaction was 95.5% (21/22) at 3 months visit, and 100% at the last visit. No differences in terms of visual acuity and satisfaction were found between the myopia and hyperopia groups.Conclusion: The PresbyMAX monocular ablation profile was safe and effective in treating presbyopia, with great satisfaction achieved at postoperative 1 year.

Objective optical quality and visual outcomes after the PresbyMAX monocular ablation profile.

To assess objective visual quality after presbyopia correction using the PresbyMAX monocular mode. This prospective, nonrandomized study included 28 eyes from 18 patients (mean age 50.4±5.6y) who underwent presbyopia correction with the PresbyMAX monocular mode. Monocular and binocular visual acuities were evaluated preoperatively, 1d, 1wk, 1, 3mo, and 1y after surgery. Optical quality was analyzed by Hartmann-Shack wavefront aberration supported cornea ablation. Modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scattering index (OSI) were analyzed using an optical quality analysis system. One year after surgery, 100% and 94.4% of patients achieved binocular uncorrected distance and near visual acuity of 20/25, respectively. At the last visit Spherical aberration and total higher aberration were higher than the corresponding preoperative levels (P<0.001); however, no significant difference was found in MTF, OSI, or Strehl ratio. Transient decreases in OSI and MTF mainly occurred in the nondominant eyes. There was no significant difference in optical quality between the dominant and nondominant eyes, except for spherical aberration and horizontal coma (P<0.05). The PresbyMAX monocular mode is safe and effective for presbyopia correction. It has little effect on optical quality, though short-term degraded optical quality occurred mainly in the bi-aspheric ablated eyes.

Loop Closure Detection Via Maximization of Mutual Information

An image can be described in terms of appearance frequency of visual words. This representation is implemented in bag-of-visual-words (BoVW)-based loop closure detection for its efficiency and effectiveness. However, traditional BoVW-based approaches are strongly affected by false positive loops due to scene ambiguity caused by redundant words in the vocabulary and fail to detect bidirectional loops in monocular mode. Aiming at overcoming these problems, we propose a novel vocabulary construction algorithm named hierarchical sequential information bottleneck (HsIB) by leveraging the maximization of mutual information (MMI) mechanism. First, feature descriptors are extracted from training images for visual vocabulary construction. Second, HsIB extracts discriminative yet informative visual words through the MMI mechanism in vocabulary construction, which treats feature descriptors clustering as a process of data compression. Finally, the clustering process reaches a tradeoff between compactness and discrimination and improves the performance of traditional BoVW-based loop closure detection. The proposed method is compared with state-of-the-art methods on publicly available datasets. We also create a challenging dataset to further evaluate the performance of HsIB on bidirectional loops. To the best of our knowledge, we are the first to implement information bottleneck (IB) method in visual-SLAM (vSLAM) loop closure detection, and we obtain impressive results.

The Cosmic Ray Energy Spectrum between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode

Abstract We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). The TALE air FD is also sensitive to the Cherenkov light produced by shower particles. Low-energy cosmic rays, in the PeV energy range, are detectable by TALE as Cherenkov events. Using these events, we measure the energy spectrum from a low energy of ∼2 PeV to an energy greater than 100 PeV. Above 100 PeV, TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we describe the detector, explain the technique, and present results from a measurement of the spectrum using ∼1000 hr of observation. The observed spectrum shows a clear steepening near 1017.1 eV, along with an ankle-like structure at 1016.2 eV. These features present important constraints on the origin of galactic cosmic rays and on propagation models. The feature at 1017.1 eV may also mark the end of the galactic cosmic ray flux and the start of the transition to extragalactic sources.

The Effectiveness of Using Stereoscopic 3D for Proportion Estimation in Product Design Education

In product design education, identifying proportion and manipulating proportional relationships are important practices in form-giving training. However, using conventional 2D displays with monocular depth cues to train students with different spatial abilities remains a great challenge. Although, some literature has indicated that stereoscopic 3D (S3D) displays were helpful for depth-related tasks, whether S3D is helpful for proportion estimation is an open question. Therefore, the objective of this research was to study whether using S3D for design department students could assist them in improving their ability to interpret the proportions of products. The independent variables of the experiment included spatial ability, task complexity, and display mode. Spatial ability was a between-subject variable. Students aged 20–25 years were recruited as participants and were categorized into high-, moderate-, and low-performance groups depending on their score on a spatial ability scale. Task complexity and display mode were within-subject variables. In the experiment, three chair styles were used as samples. Digital models of three chairs with distinct proportions were displayed in two conditions: 2D mode with monocular depth cues and S3D mode. Participants were asked to compare the proportions of a physical chair and three digital chairs and then select the digital chair with the correct proportions in the 2D and S3D modes. The dependent variable were the score of selecting the 3D digital models with correct proportions compared to the physical objects. The result indicated that students could perceive proportions more accurately in the S3D mode than in the 2D mode. In particular, when using S3D, participants with low spatial ability demonstrated overall performance that was equal to that of participants with high spatial ability.

A High Spatial Resolution Depth Sensing Method Based on Binocular Structured Light.

Depth information has been used in many fields because of its low cost and easy availability, since the Microsoft Kinect was released. However, the Kinect and Kinect-like RGB-D sensors show limited performance in certain applications and place high demands on accuracy and robustness of depth information. In this paper, we propose a depth sensing system that contains a laser projector similar to that used in the Kinect, and two infrared cameras located on both sides of the laser projector, to obtain higher spatial resolution depth information. We apply the block-matching algorithm to estimate the disparity. To improve the spatial resolution, we reduce the size of matching blocks, but smaller matching blocks generate lower matching precision. To address this problem, we combine two matching modes (binocular mode and monocular mode) in the disparity estimation process. Experimental results show that our method can obtain higher spatial resolution depth without loss of the quality of the range image, compared with the Kinect. Furthermore, our algorithm is implemented on a low-cost hardware platform, and the system can support the resolution of 1280 × 960, and up to a speed of 60 frames per second, for depth image sequences.

The hybrid energy spectrum of Telescope Array’s Middle Drum Detector and surface array

The Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated when a primary cosmic ray particle interacts with the atmosphere. Meanwhile, scintillator detectors measure the lateral distribution of secondary shower particles that hit the ground. The Middle Drum (MD) fluorescence telescope station consists of 14 telescopes from the High Resolution Fly’s Eye (HiRes) experiment, providing a direct link back to the HiRes measurements. Using the scintillator detector data in conjunction with the telescope data improves the geometrical reconstruction of the showers significantly, and hence, provides a more accurate reconstruction of the energy of the primary particle. The Middle Drum hybrid spectrum is presented and compared to that measured by the Middle Drum station in monocular mode. Further, the hybrid data establishes a link between the Middle Drum data and the surface array. A comparison between the Middle Drum hybrid energy spectrum and scintillator Surface Detector (SD) spectrum is also shown.

The Mass Composition of Ultra-high Energy Cosmic Rays Measured by New Fluorescence Detectors in the Telescope Array Experiment

The longitudinal development of an extensive air shower reaches its maximum at a depth, Xmax, that depends on the species of the primary cosmic ray. Using a technique based on Xmax, we measure the cosmic-ray mass composition from analyses of 3.7 years of monocular mode operations with the newly constructed fluorescence detectors of the Telescope Array experiment. The Xmax analysis shows our data to be consistent with a proton dominant composition at energies above 1018.0eV.

The energy spectrum of ultra-high-energy cosmic rays measured by the Telescope Array FADC fluorescence detectors in monocular mode

We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array’s third fluorescence detector [T. Abu-Zayyad et al., The energy spectrum of Telescope Array’s middle drum detector and the direct comparison to the high resolution fly’s eye experiment, Astroparticle Physics 39 (2012) 109-119, http://dx.doi.org/10.1016/j.astropartphys.2012.05.012, Available from: <arXiv:1202.5141>]. This combined spectrum corroborates the recently published Telescope Array surface detector spectrum [T. Abu-Zayyad, et al., The cosmic-ray energy spectrum observed with the surface detector of the Telescope Array experiment, ApJ 768 (2013) L1, http://dx.doi.org/10.1088/2041-8205/768/1/L1, Available from: <arXiv:1205.5067>] with independent systematic uncertainties.

Energy spectrum of UHECRs measured by newly constructed fluorescence detectors in Telescope Array experiment

Telescope Array (TA) experiment is the largest hybrid detector to observe ultra-high energy cosmic rays (UHECRs) in the northern hemisphere. In the TA experiment, we newly designed and constructed 24 fluorescence detectors (FDs) located at two stations. We report the energy spectrum of UHECRs with energies above 10 17.5 eV from analyzing data collected by the new FDs during the first 3.7 years in monocular mode.

The energy spectrum of Telescope Array’s Middle Drum detector and the direct comparison to the High Resolution Fly’s Eye experiment

The Telescope Array’s Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly’s Eye’s HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a three-year exposure collected between December 16, 2007 and December 16, 2010. The calculated difference between the spectrum of the Middle Drum observations and the published spectrum obtained by the data collected by the HiRes-1 site allows the HiRes-1 energy scale to be transferred to Middle Drum. The HiRes energy scale is applied to the entire Telescope Array by making a comparison between Middle Drum monocular events and hybrid events that triggered both Middle Drum and the Telescope Array’s scintillator ground array.

Measurement of the flux of ultra high energy cosmic rays by the stereo technique

The High Resolution Fly’s Eye (HiRes) experiment has measured the flux of ultrahigh energy cosmic rays using the stereoscopic air fluorescence technique. The HiRes experiment consists of two detectors that observe cosmic ray showers via the fluorescence light they emit. HiRes data can be analyzed in monocular mode, where each detector is treated separately, or in stereoscopic mode where they are considered together. Using the monocular mode the HiRes collaboration measured the cosmic ray spectrum and made the first observation of the Greisen–Zatsepin–Kuzmin cutoff. In this paper we present the cosmic ray spectrum measured by the stereoscopic technique. Good agreement is found with the monocular spectrum in all details.

Studies of systematic uncertainties in the estimation of the monocular aperture of the HiRes experiment

We have studied several sources of systematic uncertainty in calculating the aperture of the High Resolution Fly’s Eye experiment (HiRes) in monocular mode, primarily as they affect the HiRes-II site. The energy dependent aperture is determined with detailed Monte Carlo simulations of the air showers and the detector response. We have studied the effects of changes to the input energy spectrum and composition used in the simulation. A realistic shape of the input spectrum is used in our analysis in order to avoid biases in the aperture estimate due to the limited detector resolution. We have examined the effect of exchanging our input spectrum with a simple E −3 power law in the “ankle” region. Uncertainties in the input composition are shown to be significant for energies below ∼10 18 eV for data from the HiRes-II detector. Another source of uncertainties is the choice of the hadronic interaction model in the air shower generator. We compare the aperture estimate for two different models: QGSJet01 and SIBYLL 2.1. We also describe the implications of employing an atmospheric database with hourly measurements of the aerosol component, instead of using an average as has been used in our previously published measurements of the monocular spectra.

Results from the HiRes Experiment

The High Resolution Fly's Eye (HiRes) Experiment has been in operation in monocular mode since 1997 and in stereo mode since late 1999. The published HiRes monocular spectrum is consistent with the GZK Suppression at 1019.8 eV and observes an ankle structure at 1018.5 eV. The preliminary stereo spectrum is consistent with the monocular spectrum. Various anisotropy studies with both monocular and stereo data have yielded null results. However, a possible correlation between HiRes stereo events taken before Jan., 2004 and BL-Lac objects has been reported, but remains to be verified or refuted by the analysis of the Hires data taken after Feb., 2004. Composition studies of Hires stereo data shows a predominantly light composition in the energy range 1018.0–1019.3 eV. We also report on the result of the proton-air cross section measurement from the tails of the XMAXdistribution.

Observation of the ankle and evidence for a high-energy break in the cosmic ray spectrum

We have measured the cosmic ray spectrum at energies above 1017eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the “ankle” near 3×1018eV, and strong evidence for a suppression near 6×1019eV.