Visibility Conditions Research Articles

Application of photogrammetry and laser scanner on the Bronze Age structures of the Castillejos de Luna cist tomb necropolis (Pizarra, Spain)

The cist tombs necropolis at Castillejos de Luna, in Sierra de Gibralmora-Sierra del Hacho (Pizarra, Málaga, Spain) was known from the graphic documentation and the grave goods of two tombs. New studies have documented nine burials. The aim of this article is to present the new virtualisation work that has been carried out in the necropolis, to generate a new three-dimensional (3D) documentation of the currently known records, which are in acceptable visibility conditions. Using tools to document tombs in 3D offers us great advances in data acquisition and editing, with great precision and realism, thanks to the 3D models generated through techniques such as photogrammetry or laser scanning. Thanks to these tools, it is possible to carry out studies on digital twins and use them as informative material for society. The study this paper describes has generated high quality products for dissemination and future analysis. The results shown here are of metric character, with orientation and geographical location of the structures. In addition, in one of the tombs the authors show the combination of photogrammetric techniques with laser scanners to obtain a single high-resolution 3D model; subsequently a retopology process is carried out to achieve a "light" model with a photorealistic appearance that is both easily manipulated on mobile devices for its dissemination and a guarantee that the general public can enjoy this necropolis in a different way. The preliminary results are published in the web repository of 3D models Sketchfab, where the users can see a preview of one of the tombs before and after being optimised with retopology through Blender. The authors provide a socio-historical analysis of Bronze Age necropolises in central Andalusia, within the framework of a debate on the western expansion of the El Argar Culture.

Effect of MIMO scheme on MWIR FSO link & comparison with SWIR wavelength in the presence of different visibility and strong turbulence circumstances

Abstract In this article, the authors analyse the performance of the “multiple input multiple output (MIMO)” technique on a free space optical (FSO) communication link using the mid wavelength infrared (MWIR) and commonly used short wavelength infrared (SWIR) in the presence of various visibility conditions like clear weather, light haze, dense haze, fog, etc., and strong turbulence regime. A 5 km link range has been considered with different diversity MIMO schemes. The performance analysis has been made for both wavelengths in terms of bit error rate (BER) and link outage probability. As the MIMO diversity is increased, the performance has been improved compared to the single input single output (SISO) scheme. In the presence of foggy conditions and higher turbulence strength, the MWIR wavelength works properly, whereas the SWIR wavelength has not worked for the same signal to noise (SNR) ratio and the same link distance.

Analysis of human errors in maritime accidents: A Bayesian spatial multinomial logistic model

Considering the unobserved spatial heterogeneity, this study aims to build a Bayesian spatial multinomial logistic (BSMNL) model by utilizing the geographic information from historical maritime accidents. The proposed BSMNL model can be applied to investigate the determinants of human errors involved in maritime accidents. Compared to the traditional multinomial logistic (MNL) model, the proposed BSMNL model produces a more accurate estimate of the effects of environmental and accident factors on the occurrence likelihood of human errors in maritime accidents. Results show that accidents involving cargo and container ships; tankers carrying liquefied natural gas (LNG), liquefied petroleum gas (LPG), or oil; and fishing vessels are more likely to be associated with human errors. Further, one important finding is that the involvement of fishing vessels significantly increases the occurrence probability of both negligence errors and judgment or operational errors. In addition, the occurrence likelihood of human errors is generally higher in springtime, conditions of poor visibility, the absence of strong winds or waves, and the moored or docked status.

Traffic planning for the protection of vulnerable groups of persons exemplified by the City of Munich

Pedestrian and bicycle traffic make asignificant contribution to the traffic turnaround. Measures to improve the road safety of pedestrians and cyclists are insofar an important building block to asuccessful sustainable city and traffic planning. The mobility strategy 2035 of the City of Munich includes partial strategies for walking and cycling as well as for road safety, which was confirmed through former city council resolutions on Vision Zero. The most important measures for the comfort and safety of pedestrians are aspeed limit of 30 km/h, wide and free sidewalks (without obstacles) and crossing assistance with good visibility conditions. Depending on the local situation, sidewalk extensions, road islands, pedestrian crossings (zebra crossings) and traffic lights with attractive circuit conditions for pedestrians make crossing easier. The comfort and safety of cyclists can be improved with broad cycling paths along the main streets. They should allow the overtaking of cyclists in both directions. At least on side streets, acomprehensive speed limit of 30 km/h is an important issue. One-way streets should be open for oncoming cyclists against the one-way direction. At road crossings and road junctions the visibility of cyclists should be improved with road markings and widened bike lanes and there should be aconflict-free circuit of traffic lights, especially where there is ahigh percentage of commercial vehicles.

FSO communication system for high-speed trains under varying visibility conditions

High-speed train systems are rapidly growing in complexity and coverage, demanding efficient high-speed internet services. Existing radio frequency technology struggles to meet these demands due to handover mechanisms and limited connectivity times. Furthermore, current free-space optics (FSO) techniques require a large number of base stations (BSs), resulting in high costs. This study presents a novel high-speed train communication technique, using FSO, that significantly reduces the number of required BSs while maintaining sufficient coverage and data speeds. The proposed technique can be adapted for fixed or variable representations of transmitted and received power, providing a fixed or variable data rate. The research also investigates the impact of divergence angle on transmitted and received power. By employing the proposed communication technique, a system with a fixed data rate, such as 1.25 Gbps, can be achieved. The results demonstrate the potential of this approach in high-speed train applications, reducing the number of BSs from 113, as reported in the best existing literature, to less than 10. Weather conditions, including clear, haze, thin fog, light fog, and heavy fog, are considered when calculating the required BS locations to achieve a target data rate. Additionally, this work introduces a new handover mechanism and mathematical formulation, providing a more comprehensive solution for high-speed train communication systems. The simulations and evaluations conducted in this study are based on parameters and equations from previous works to ensure a fair comparison.

Updating Visibility Chart Bandar Udara Internasional Sultan Hasanuddin Makassar

This research aims to update the Aerodrome Visibility Chart at Sultan Hasanuddin International Airport in Makassar. The research method used is qualitative, conducting observations on the research object, namely the Aerodrome Visibility Chart. The results of the study indicate the presence of 5 points that can serve as references in updating the Aerodrome Visibility Chart at Sultan Hasanuddin International Airport. These points include the Radio Antenna, Holten Dalton Building (as an update from Grand Quality Hotel), Taman Sari Development Project, New Terminal Building, and Grand Mall Maros. The conclusion of this research emphasizes the need to update the Aerodrome Visibility Chart at Sultan Hasanuddin International Airport, taking into account the identified points, in order to provide more accurate and relevant information regarding visibility conditions around the airport.

4DEgo: ego-velocity estimation from high-resolution radar data

Automotive radars allow for perception of the environment in adverse visibility and weather conditions. New high-resolution sensors have demonstrated potential for tasks beyond obstacle detection and velocity adjustment, such as mapping or target tracking. This paper proposes an end-to-end method for ego-velocity estimation based on radar scan registration. Our architecture includes a 3D convolution over all three channels of the heatmap, capturing features associated with motion, and an attention mechanism for selecting significant features for regression. To the best of our knowledge, this is the first work utilizing the full 3D radar heatmap for ego-velocity estimation. We verify the efficacy of our approach using the publicly available ColoRadar dataset and study the effect of architectural choices and distributional shifts on performance.

LVRNet: Lightweight Image Restoration for Aerial Images under Low Visibility (Student Abstract)

Learning to recover clear images from images having a combination of degrading factors is a challenging task. That being said, autonomous surveillance in low visibility conditions caused by high pollution/smoke, poor air quality index, low light, atmospheric scattering, and haze during a blizzard, etc, becomes even more important to prevent accidents. It is thus crucial to form a solution that can not only result in a high-quality image but also which is efficient enough to be deployed for everyday use. However, the lack of proper datasets available to tackle this task limits the performance of the previous methods proposed. To this end, we generate the LowVis-AFO dataset, containing 3647 paired dark-hazy and clear images. We also introduce a new lightweight deep learning model called Low-Visibility Restoration Network (LVRNet). It outperforms previous image restoration methods with low latency, achieving a PSNR value of 25.744 and an SSIM of 0.905, hence making our approach scalable and ready for practical use.

THE PROGRAM FOR ASSESSING THE CONNECTIVITY OF NODES OF WIRELESS EPISODIC NETWORKS UNDER THE CONDITION OF USING UAVS

Background. Based on analytical mathematical models, the duration of connectivity of mobile subscribers (nodes) (MS) of a wireless episodic network (WEN, consisting of MS and UAV) was investigated in conditions of direct radio visibility and considering the relaying.
 Objective. The purpose of the work is to find methodological approaches to ensure the connectivity of WSN nodes, which is a necessary condition for obtaining information from WSN in the absence of communication infrastructure.Methods. Simulation modelling based on MAPLE 14 software package and analytical calculation methods are used.
 Results. It is shown that the duration of connectivity is directly proportional to the size of the coverage area and inversely proportional to the movement speed of nodes. The mobility nature (scenario) of nodes also affects the duration of connectivity. The simulation of the nodes' movement was carried out under 4 scenarios: "march", "incoherent", "random wandering in the field" and "random wandering in the city". The largest values of the connectivity duration correspond to the third scenario, and the smallest - to the second (with a fixed radius of the coverage area and the movement speed of nodes). Thus, the average connectivity duration of the UAV-pedestrian connection in the event of an "incoherent" will be about 36 minutes, and the UAV-car connection - about 5 minutes.
 Conclusions. The system and functional parameters of the networks, which were obtained as a result of the research, will form the basis of the initial data and limitations of the mathematical model, and will also make it possible to determine the initial placement of the UAV network at the planning stage.

Walking performance of pedestrians in corridors under different visibility conditions

Visibility is an important factor affecting pedestrian movement and safe evacuation. To investigate the walking characteristics of pedestrians under limited visibilities, a novel measurement method by changing the light transmittance in a suitable lighting environment is proposed to achieve different visibility levels. A series of individual movement experiments were performed under the quantitative control of visibility condition. Stoop-walking behavior was observed at low visibility levels. Besides, pedestrians would stretch out their arms or feet to explore the surrounding environment under invisible conditions. Based on the high-precise trajectories, it is found that the acceleration and relaxation time of individuals increase with the improvement of visual condition. The walking speed of males is significantly larger than that of females at the same visibility level. Moreover, individual speed increases with the improvement of visibility level, but no significant difference is found when the visual distance is larger than 6 m. In addition, individuals prefer to change movement direction rather than reduce the speed to avoid the frontal obstacle or pedestrians under limited visibilities. Furthermore, comparison between previous studies and our work is made, and their differences are also elaborated. The study can help to quantitatively predict pedestrian’s speed and develop movement models for limited visibility situations.

Evacuation performance on offshore platforms under different visibility conditions

Evacuation performance on offshore platforms under different visibility conditions

SBAS-based navigation system for precision approach in CAT II LVC

Due to lack of advanced navigation systems, secondary airports are normally unable to support instrument approaches in low visibility conditions (LVC) more adverse than Category (CAT) I, making them inaccessible during such conditions. Incoming flights are then delayed, diverted to adjacent airports, or cancelled before take-off. This paper presents an onboard navigation solution, under development in scope of SESAR 2020 Solution PJ02-W2- 17.2, which focuses on technology development to mitigate these traffic disruptions by enabling instrument approaches in CAT II LVC with minimum airport and air navigation service provider investments. The concept builds upon global navigation satellite systems (Global Positioning System L1 frequency – GPS L1, satellite-based augmentation system), which currently enables Localizer Performance with Vertical guidance (LPV) operation down to LPV 200 minima. The designed system includes radio altimeter-based aiding and innovative integrity algorithm to improve navigation performance in support of operations below 200ft down to CAT II / LPV 100 minima. As no such requirements have yet been officially published, authors also defined sets of candidates based on Instrument Landing System Collision Risk Model and other sources. The team developed and verified a Monte-Carlo fast-time simulation toolset to enable representative and statistically significant evaluation of the concept feasibility via its availability throughout Europe, as well as sensitivity to proposed sets of alert limits. Also, flight data collection and a developed software prototype allow for further validations. Simulations demonstrated over 95% average availability with the best results achieving level of 99% depending on used set of requirements. The solution enabling operations in LVC allows unlocking various benefits to business/airline operators (e.g., avoided extra costs, increased predictability), passengers (avoided opportunity loss) and airports (retained profit from flights, less traffic at diversion airports). Technology development also marks an important step towards gate-to-gate autonomous operations.

A Return to the Sextant—Maritime Navigation Using Celestial Bodies and the Horizon

Satellite navigation over recent decades has become the default and, in some cases, sole source of positioning for maritime vessels. The classic sextant has been all but forgotten by a significant number of ship navigators. However, recent risks to RF-derived positioning by jamming and spoofing have resurfaced the need to train sailors again in the art. Innovations in space optical navigation have long been perfecting the art of using celestial bodies and horizons to determine a space vessel’s attitude and position. This paper explores their application to the much older ship navigation problem. Models are introduced that utilize the stars and horizon to derive latitude and longitude. When assuming good star visibility conditions on the ocean, the accuracy delivered is at the 100 m level. This can meet requirements for ship navigation in coastal and oceanic voyages.

LOS and NLOS identification in real indoor environment using deep learning approach

Visibility conditions between antennas, i.e. Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) can be crucial in the context of indoor localization, for which detecting the NLOS condition and further correcting constant position estimation errors or allocating resources can reduce the negative influence of multipath propagation on wireless communication and positioning. In this paper a Deep Learning (DL) model to classify LOS/NLOS condition while analyzing two Channel Impulse Response (CIR) parameters: Total Power (TP) [dBm] and First Path Power (FP) [dBm] is proposed. The experiments were conducted using DWM1000 DecaWave radio module based on measurements collected in a real indoor environment and the proposed architecture provides LOS/NLOS identification with an accuracy of more than 100% and 95% in static and dynamic senarios, respectively. The proposed model improves the classification rate by 2-5% compared to other Machine Learning (ML) methods proposed in the literature.

Four decades of aviation visibility at Bhairahawa airport, gateway to Buddha's birthplace Lumbini, Nepal

Over four decades of visibility data at Bhairahawa airport (BWA), a recently upgraded international airport near Lumbini, a UNESCO heritage site in Nepal has been analyzed. In this study, we also investigated one of the important microclimatic behavior of fog i.e., onset and dispersal timings, and its implication on aviation. Temporal variations of poor visibility conditions at BWA are found to be primarily associated with variations in haze and fog. Haze at BWA accounts for the highest percentage (∼27%) of time and its annual occurrence is increasing (0.57% yr−1). There is a significant upward trend of hazy days in all seasons, the highest (1.46% day yr−1) being in post-monsoon. The overall seasonal poor visibility, too, has increased significantly in all seasons, with the highest trend in post-monsoon (1.57% yr−1). Similarly, fog frequency in the winter season has also increased noticeably for fog days (1.05% day yr−1), dense fog days (0.51% day yr−1), general fog hours (0.55% hour yr−1) and dense fog hours (0.20% hour yr−1). We found that fog at BWA is usually formed overnight and dissipates before noon. Daytime onset and late dispersion of fog are more common in the peak winter months of December and January. Further, we investigated the relationship between visibility and aerosol optical depth (AOD) and found a moderate negative correlation (r = − 0.66, p < 0.001) between them in the monsoon season. However, AOD is found to have a weaker correlation with visibility during winter (r = −0.36) and pre-monsoon (r = −0.23) seasons, when there is a more pronounced influence of meteorological conditions on the occurrence of visibility. We have observed a better correlation (r = −0.74) between fine particulate matter concentration (PM2.5) and visibility. Examining the effect of relative humidity (RH) on AOD (or, PM2.5) and visibility revealed that higher RH tends to lower visibility. Visibility at BWA airport is gradually worsening due to local and regional air pollution emissions and changing meteorological conditions. The degraded visibility at BWA airport will negatively impact flight safety and timeliness. Effective implementation of regionally coordinated air pollution mitigation measures can be a sustainable step towards the improvement of visibility in long run. However, the installation of ground equipment like CAT-II/III Instrument Landing System (ILS) for aircraft take-off and landings, and advanced surface movement guidance and control system (A-SMGCS) are highly advisable to lessen the damage potential to aviation.

Marine birds: Vision-based wind turbine collision mitigation

Throughout their evolution seabirds have not had to contend with the collision risk posed by discrete objects that extend into their flight space above the water surface. However, the recent introduction of offshore wind turbines has significantly increased the potential for collisions. Bird collision risk with Offshore Wind Farm (OWF) turbines is now a major consenting consideration for OWF projects due to potential local population impacts on birds, especially those associated with protected sites. Therefore, the possibility of reducing those risks through a simple mitigation is highly desirable. Key elements for the design of vision-based mitigation measures aimed at reducing the collision of marine birds with wind turbines should be based upon knowledge of the vision of birds, not the vision of humans. May et al. (2020) tested a vision-based wind turbine mitigation measure and reported a modelled 70% reduction in annual turbine-blade collision mortality rate at a terrestrial location in a suite of 19 bird species. The aim of the present proposals is to extend this vision-based mitigation approach and increase its applicability to a broad suite of bird species considered vulnerable to collisions with wind turbines at sea. Key aspects of the vision, behaviour and ecology of marine birds which contribute to their collision risk under a range of natural viewing conditions are reviewed. The same information is then employed to give insights into the requirements of vision-based mitigation measures. We argue that the internal visual contrast of wind turbines should be increased using achromatic patterns applied to blades and pylons. These patterns should reduce the collision vulnerability of marine birds in general and should be effective under a range of visibility conditions determined by natural light levels and weather conditions. The measures should allow birds with different flight speeds and visual acuities to detect turbines sufficiently early to allow alteration of flight direction and avoid collision. The proposed mitigation requires changes to the appearance of wind turbines that can be implemented at the time of manufacture. They do not interfere with statutory requirements already required for the marking of turbines for the benefit of shipping and aircraft.

Безпека пішоходів на дорозі у темну пору доби в умовах планових та аварійних відключень електроенергії в Україні

The issue of ensuring the safety of pedestrians during their movement in the dark, in particular in the absence of street lighting (in connection with rolling blackouts and emergency power outages caused by massive Russian missile attacks on the energy infrastructure of Ukraine) was considered, with the coverage of this aspect traffic safety, like the behavior of pedestrian. An analysis of the experience of European countries in the issue of pedestrian safety at night has been carried out. In particular, it was found out that in the legislation of certain European countries (in particular, such as Norway, Great Britain, Finland, Lithuania, Latvia, Estonia, the Czech Republic), norms are defined regarding the mandatory use of light-reflecting elements (flickers) by pedestrians in the dark. At the same time, the factors affecting the risk of traffic accidents in conditions of insufficient visibility were considered, in particular, such as insufficient lighting or the complete absence of road lighting, pedestrians not using light-reflecting elements (flickers) or bright clothing, especially at dusk and in night time. Recommendations were also made regarding possible actions to strengthen the safety of pedestrians at the national level during their movement in the dark, in particular in the part related to the introduction of changes to the tasks and measures for the implementation of the State program for improving the level of road safety in Ukraine for the period until 2023 of the year, approved by the Resolution of the Cabinet of Ministers of Ukraine dated 21.12.2020 No. 1287 (as amended by the Resolution of the Cabinet of Ministers of Ukraine dated 12.07.2021 No. 706), paying due attention to measures aimed at improving pedestrian safety. Keywords: car, traffic safety, pedestrian, light-reflecting element, flicker.

Entropy and a sub-group of geometric measures of paths predict the navigability of an environment

Despite extensive research on navigation, it remains unclear which features of an environment predict how difficult it will be to navigate. We analysed 478,170 trajectories from 10,626 participants who navigated 45 virtual environments in the research app-based game Sea Hero Quest. Virtual environments were designed to vary in a range of properties such as their layout, number of goals, visibility (varying fog) and map condition. We calculated 58 spatial measures grouped into four families: task-specific metrics, space syntax configurational metrics, space syntax geometric metrics, and general geometric metrics. We used Lasso, a variable selection method, to select the most predictive measures of navigation difficulty. Geometric features such as entropy, area of navigable space, number of rings and closeness centrality of path networks were among the most significant factors determining the navigational difficulty. By contrast a range of other measures did not predict difficulty, including measures of intelligibility. Unsurprisingly, other task-specific features (e.g. number of destinations) and fog also predicted navigation difficulty. These findings have implications for the study of spatial behaviour in ecological settings, as well as predicting human movements in different settings, such as complex buildings and transport networks and may aid the design of more navigable environments.

FROM “TEXT FOR LOCATION” TO “NO PHONE ON THE DANCE FLOOR”: NEGOTIATING VISIBILITY IN UNDERGROUND ELECTRONIC/DANCE MUSIC

The mediation of mobile and social media technologies has reshaped how people imagine, understand, and, in turn, calibrate the visibility of their self-expression, information sharing, and relationship-building. This paper presents a case study of how promoters and attendees in underground electronic/dance music culture (EDMC) maintained the boundaries of the “underground” by co-constructing norms of mobile and social media use. Drawing upon 20 nights of field observations at live music events and 27 semi-structured interviews with promoters and attendees, I highlighted two scenarios in which promoters and attendees leveraged the spatial and temporal affordances of mobile and social media to calibrate their visibility. First, the last-minute and indirect sharing of event location afforded the community to bar outsiders from entering while allowing insiders to authenticate themselves by navigating to their gatherings. Second, the dialectical shaping between promoters’ venue policies and attendees’ folk theories of phone etiquette maintained a reduced level of mobile media use at such gatherings. These practices brought to light how mobile and social media afford new spatial-temporal conditions of visibility and bring forth new possibilities for people to not only manage – but play with visibility.

Methods of fog control for a vehicle windscreen before vehicle moving off

INTRODUCTION: In any type of vehicle, the accessory equipment system of air heating and conditioning should ensure safety by means of glazing protection from fogging with high operational speed and minimal energy consuming, as drivers reaction slows down in low visibility conditions and the risk of road accidents increases.&#x0D; AIMS: Analytical review of state-of-the-art methods of efficiency improvement of condensate cleaning from the inner surface of a vehicle windscreen in order to discover promising methods of fog control before vehicle moving off which are energy efficient and driver- and passenger-friendly.&#x0D; LINE OF RESEARCH: Review of publications, dedicated to issues of condensate cleaning and vehicle glazing prevention from fogging.&#x0D; METHODS: Study and analysis of papers in the mentioned area, published in open sources.&#x0D; RESULTS: Conditions of fogging on inner surfaces of vehicle glazing are discussed. Russian and foreign regulatory documents, featuring demands to the procedure of fog cleaning from the windscreen inner surface, are given. Special aspects of air drying in cabin of electric vehicles and ICE-driven vehicles and various methods of the windscreen inner surface heating are considered.&#x0D; CONCLUSIONS: Efficiency of windscreen condensate cleaning may be increased significantly by means of conjuction of such methods as: a) making inner surfaces of vehicle glazing hydrophobic; b) defroster design optimization in order to ensure air supply having minimal pressure losses, maximal output mass, high speed and uniform distribution of airflow along the surface of critically important fields of view; c) using of tempered windscreens with transparent electrically-conducting layer; d) drying of vehicle cabin air. At present, the search for efficient methods of windscreen warming and cabin air drying in recirculation mode for both electric vehicles and ICE-driven vehicles, operating in low air temperature conditions, continues.