KEEPING THE BENEFIT OF ILMD’s HIGH RESOLUTION IN MEASURING LIGHTING QUALITY PARAMETERS

The dimensioning of lighting installations is performed according to the specifications of CIE documents and relevant standards. Differences are often observed between simulations and experimental measurements regarding the quality criteria and luminance distributions. This paper deals with road lighting quality parameters evaluation between experimental ILMD images and calculations. Influence of image rectification is first examined. Impacts of image resolution, grid resolution and grid positioning on average luminance, overall uniformity and longitudinal uniformity are evaluated. An elliptical method based on human eye resolution and perspective projection is presented for road lighting calculations. It conducts to a good robustness regarding misalignment and give access to a pixel-to-pixel comparison with experimental ILMD images.

QUANTIFICATION OF THE EFFECT OF LIGHTING ENVIRONMENT ON SPACIOUSNESS OF INTERIOR SPACE

Spaciousness is an important quality of space which is affected by both the volume of space and the lighting environment. This study’s aim is to create the calculation model to quantify the effect of lighting environment on spaciousness. 3D luminance mapping, which is the combined data of luminance of surface and its distance to the observer, is used for the analysis of lighting environment, because we hypothesized that the three-dimensional localization of light affects the spaciousness. From the result of a subjective experiment to evaluate spaciousness with different lighting environment, it is revealed that spaciousness can be quantified from average luminance and “Dark-part-reduced visible volume” which is the reduced visible volume according to the distribution of dark pixels in the 3D luminance mapping. We also compared average illuminance of whole image and of ceiling, walls, floor, and concluded that the whole average illuminance best describes the effect.

Assessment the Visual Clarity of the Projector in Classroom and Innovative Asymmetric Distribution LED Tube Applications

The paper aims to explore the relationship between the vertical plane luminance on projection screens and human visual clarity in the classroom or meeting room. While controlling the lighting environment conditions of the classroom to create different luminous distributions and luminance on the projection screen, a survey is conducted to understand students’ visual experience about screen clarity during the field experiment. The luminance of each picture on the projection screen is measured under the specified lighting conditions of luminaires in the classroom, and the relationship is formulated between the average luminance on the projection screen and the visual satisfaction based on clarity of experience. This will be useful for further studying the acceptable threshold of luminance distribution in the classroom to provide a better visual clarity and lighting quality of projection screens while teaching. In this study, the measurement and performance evaluation on a projection screen were carried out at a classroom in the National Taiwan University of Science and Technology (NTUST). By using an image luminance meter and analyzing the research results, we propose an improvement strategy for asymmetric luminous distribution design of LED light tube and light switch control mechanism of luminaires to resolve the inadequate luminance of the vertical projection screen area to improve the lighting quality and visual clarity of the projection screen while teaching with the least cost.

Influence of Pavement Heterogeneity and Observation Angle on Lighting Design: Study with New Metrics

Optimization of lighting installations should be a priority in order to reduce energy consumption and obtrusive light while providing optimal visibility conditions for road users. For the design of lighting installations, it is assumed that the road has homogeneous photometric characteristics and only one viewing angle is used. There are often significant differences between the design of lighting installations and their actual performance. In order to examine whether these differences are due to the photometry of the road, this study proposes metrics to assess the influence of road heterogeneity and observation angle. These metrics have been used on many measurements conducted on site and in the laboratory for different pavements. A calculation engine has been developed to realize road lighting design with several r-tables in the same calculation or for different observation angles. Thus, this study shows that a root mean squared deviation (RMSD) calculation, including average luminance and uniformities associated with different r-tables, is directly correlated to a normalized root mean squared deviation (NRMSD) calculation between these r-tables. With these proposed metrics it is possible to optimize lighting installation while taking into account different types of urban surfaces and the diversity of users.

Real-Time Monocular Vision System for UAV Autonomous Landing in Outdoor Low-Illumination Environments

Landing an unmanned aerial vehicle (UAV) autonomously and safely is a challenging task. Although the existing approaches have resolved the problem of precise landing by identifying a specific landing marker using the UAV’s onboard vision system, the vast majority of these works are conducted in either daytime or well-illuminated laboratory environments. In contrast, very few researchers have investigated the possibility of landing in low-illumination conditions by employing various active light sources to lighten the markers. In this paper, a novel vision system design is proposed to tackle UAV landing in outdoor extreme low-illumination environments without the need to apply an active light source to the marker. We use a model-based enhancement scheme to improve the quality and brightness of the onboard captured images, then present a hierarchical-based method consisting of a decision tree with an associated light-weight convolutional neural network (CNN) for coarse-to-fine landing marker localization, where the key information of the marker is extracted and reserved for post-processing, such as pose estimation and landing control. Extensive evaluations have been conducted to demonstrate the robustness, accuracy, and real-time performance of the proposed vision system. Field experiments across a variety of outdoor nighttime scenarios with an average luminance of 5 lx at the marker locations have proven the feasibility and practicability of the system.

Average Luminance Calculation in Street Lighting Design, Comparison between BS-EN 13201 and RP-08 Standards

This paper presents a study on the influence of the observer’s position in relation to the calculation surface. This is the initial observation of the research, respectively that the two standards consider the position of the observer differently. For these situations, two types of calculations were performed. For the first set of calculations, the software used was DIALux 4.13 as this software can perform calculations in line with the RP-08 standard. The second set of calculations was performed with a script that offers the possibility to change the observer’s position. The conclusion was that EN-13201 has a better approach, but both standards could be improved. The second case study refers to the influence of the longitudinal observer position in an average luminance calculation. If one considers RP-08 as a guideline for performing the calculations, the conclusions are that changing the distance from the observer to the calculation surface has absolutely no effect on the average luminance value. On the other hand, if European standards are used as a guideline, changing the distance (from the standardized 60 m, either closer to the calculation surface or further away) can influence the overall results in average luminance and uniformity. Taking into account the results of these two case studies, the conclusion is that both RP-08 and BS-EN 13201 should be updated so that the observer’s distance in relation to the calculation surface would be a variable dependent on the stopping distance calculated based on the speed limit of the road.

Helmholtz Versus Haute Couture: How Horizontal Stripes and Dark Clothes Make You Look Thinner

In Helmholtz’s illusion, a square with horizontal stripes appears taller than an identical square with vertical stripes. This effect has also been observed in experiments with human stimuli, where a human figure wearing a dress with horizontal stripes appears thinner than a drawing clad in vertical stripes. These findings do not agree with the common belief that clothes with horizontal stripes make someone appear wider, neither do they disentangle whether the horizontal or vertical stripes account for the thinning effect. In the present study, we focused on the effect of horizontal stripes in clothes comparing horizontal stripes against no-stripes (not against vertical; Experiments 1 and 2), using photos of a real-life female model, and controlling for the average luminance of the stripes (Experiment 2). Results showed that horizontal stripes and lower luminance have—independently—a small-to-moderate thinning effect on the perceived size of the body, and the effect is larger when the two variables are combined. In Experiment 3, we further show that the thinning effect due to the luminance of the dress is enhanced when the general background gets darker.

Measuring Average Luminance for Road Lighting from Outside the Carriageway with Imaging Sensor

The main quality condition in street lighting is luminance distribution. During the carrying out of the literature, average luminance is the most important parameter to check. The standard BS EN 13201-3 imposes that average luminance must be calculated for the observer placed in the center of each circulating lane. As a consequence, according to these standards, the measurements can be done only on streets without traffic. Stopping the traffic on all lanes is very difficult. This paper proposes a solution for measuring the average luminance from outside the carriageway. The research was performed by simulations/calculations and was validated by field measurements. Imaging sensors were used to measure average luminance, while DIALux EVO 9.1 was used for the simulations. For symmetrical, opposite, and staggered lighting arrangements, average luminance measurements were performed with a digital camera positioned outside of the traffic area, with the equipment placed at the edge of the carriageway, giving similar results with standard measurements, with almost no difference. For single sided lighting arrangements, the differences became unacceptable. In this case, the paper proposes a correction function to calculate the average luminance for the observer placed on the carriageway, based on measurements with a digital camera placed outside the traffic area.

Optimizing Optical Film Lamination to Enhance the Luminance of TFT-LCD Displays Using the Taguchi-NNGA Method

Luminance is an essential quality of a TFT-LCD display. Manufacturers have attempted to improve the soft-to-hard lamination stage to enhance the luminance of their TFT-LCD displays. In addition, many customers have complained about the insufficient luminance of the TFT-LCD displays of the case company. While product engineers have kept tuning the control factors in the soft-to-hard lamination stage through the trial and error method, the improvement of the luminance was not good enough. This study aims to assist the product engineers to fine-tune the settings of the control factors using a new method composed of the Taguchi method, a neural network, and a genetic algorithm. The confirmation experiments showed that the proposed method had increased the average luminance of the TFT-LCD displays from 17.03 to 25.15, which was higher than the required luminance value of 25. As a result, the number of complaints on the TFT-LCD displays had been significantly reduced.

The Evaluation of the Lighting at the Entrance of Very Long Tunnels

Background: One of the major topics related to the very long tunnels is dark hole effect. This is a common phenomenon caused by the sunlight reflected from the surroundings of the tunnel to the eyes of drivers and the lack of sufficient light at the tunnels' entrance, which decreases the contrast of barriers inside the tunnel and also makes it difficult to see potential obstacles at the entrance. The result is an increased risk of traffic accidents in these tunnels. Therefore, the aim of this research is to subjectively assessment the safe rate of lighting in one of the very long tunnels located in the province of Ilam. Methods: To subject evaluation the safe rate of lighting at the tunnel entrances, two parameters of the average luminance of tunnel entrance and equivalent luminance are required. In this study, Luminancemeter device model S3 was used to measure the average luminance of tunnel entrance. Then, to calculate the equivalent luminance, a YASHICA108 camera with a 35 mm lens was photographed at a distance between the tunnel entrance and a safe stopping point, and then the Holliday polar diagram was used to calculate equivalent luminance (accordance with the standard CIE88-2004). Results: In this study, the average luminance at tunnel's entrance was equal to 17 , the luminance was equal to 127.5 Using the ADRENAL equation, the quality of lightening at the tunnel entrance was less than 1. Conclusion: Comparison of the results obtained from the healthy and safety rate of lighting levels at the tunnel's entrance with the De Boer mental scale indicated that a dark hole effect occurs at the entrance of the tunnel under investigation and the light sources installed at the entrance of this tunnel did not have the sufficient ability to inhibit the dark hole effect.