Attempt to Predict Utilization Factors on Working Plane within Shadow under Task Ambient Lighting

color images are usually viewed on CRT monitor screen under ambient light sources. The feeling for reproduced color on CRT monitor depends on white point of ambient light source and the CRT monitor screen. Therefore, if the effect of ambient light source is not considered, then the reproduced color does not match the intrinsic color. This paper proposes a method to investigate the effect of ambient light source on color appearance of a CRT monitor which is posited in a room illuminated by an experimental light source. The investigation for the effect of ambient light consists of two elements. One is the flare effect that the reflection on the CRT monitor screen which produced by the ambient light source. Another is the change of adaption in white point. When the images are viewed on a CRT monitor screen under ambient light, the sate of adaption is affected by both the white point of the monitor and ambient light source. Therefore, these two effects were analyzed in the experiments.

Shadows cast over a work area can be a significant obstacle to work. Shadows are thus an important factor in designing comfortable work environments.The problems caused by shadows produced by a globe shadow caster combined with task ambient lighting in a room were modeled. The variations of the illuminance and the as a shadow factor were obtained and examined for various positions and sizes of an ambient light with a Lambertian surface with the position of the shadow caster taken as a parameter.The most suitable position for the ambient light was found to be the center of the ceiling, and the most suitable size for it was found to be 0.6 × 0.6-1.0 × 1.0 [m2].

タスク・アンビエント照明における影の中の照度計算についての検討

In this paper, we establish an air-to-water (A2W) visible light communication (VLC) link adopting one green light emitting diode (LED) as the transmitter and one white LED as the ambient light source. The effect of the ambient light on the A2W-VLC link gain is investigated under calm and wavy water surface conditions. By transmitting a high-frequency sinusoid signal, we extract the variation of overall A2W-VLC link gain from the received signal in the presence of ambient light. The experimental results show that the strong ambient light can cause the saturation of photodiode (PD) and yield no communication possibility under calm water surface condition. Under wavy water surface condition, the effect of strong ambient light can be alleviated to some extent, yielding some communication possibilities.

Non-contact video based heart rate estimation has great various potential in areas such as medical, health care, and affective computing. Recently, the methods using a digital camera for remote heart rate (HR) measurement are widely spread. However, the accuracy of these methods are not sufficient enough to calculate heart rate variability (HRV) accurately. If HRV are measured with high accuracy, we can visualize the sympathetic nerve system by calculating heart rate variability spectrogram (HRVS). In this paper, we propose a method of HR and HRV spectrogram estimation by analyzing extracted hemoglobin concentration from facial color images. Our method does not require any special camera. Furthermore, it is possible to have a stable presumption even under the ambient light sources. As a result, we could obtain 99% accuracy of HR and HRV spectrogram with the same accuracy electrocardiogram. Therefore we succeeded to identify whether participants were relaxed or stressed using conventional DSLR camera.

The article demonstrates the condensation of water vapour under pressure and at room temperature, using a disposable syringe and an ambient light source. The small amount of trapped water vapour inside a syringe along with the air is compressed manually to one-sixth of its original volume. The compressed water vapour inside the syringe can be easily seen in the form of a white condensate on the inner side of the transparent, circular wall of the syringe. The condensate cloud can be observed in the atmosphere by releasing it in the open air while holding the syringe in front of a light source over a dark background. This model can be used as an analogous experiment while explaining the concept of condensation of gases under pressure–from school to postgraduate students.

A real-time crop sensor for site specific input application is the new innovation in the field of precision agriculture. At least three different type of crop sensors,viz.. Soil Doctor, N-Senior and Green Seeker have been used in different field crops. The key advantage of all these systems is that they do not need recommendation maps. However, no published data is available on Soil Doctor adoption by farmers due to company’s aggressiveness for protective patent rights. The N-Sensor is being used mainly for wheat and other small grain crops. However, one of the key limitations of N-Sensor is ambient light source. Handheld Green Seeker sensor is the latest addition to the list of crops sensors. The active light source is a major advantage of the Green Seeker sensor. Our preliminary observations on NDVI in relation to canopy development and crop growth in sugarcane are very encouraging and we envisage a potential scope of Green Seeker optical sensor for monitoring crop growth in order to adjust timing and dose of N application for maximizing cane and sugar productivity.

Approximately 80% of the visually impaired are composed of individuals with low vision. As people with low vision have residual visual acuity, light guidance has been deemed effective. Thus, the authors have developed a light-emitting block that is placed at the entrance to a pedestrian crosswalk to support the visually impaired at night. Generally, blinking light is accepted as a method to selectively distinguish a target light source from an ambient light source. However, on/off blinking lights, such as those used at a road construction site at night, are unsuitable for normal road environments. Therefore, the authors focused on fade-in/fade-out blinking, which gradually brightened and darkened, suppressing inappropriate visual stimulation. Therefore, this study aimed to search for blinking cycles and patterns that ensured visibility while suppressing light stimulation and reducing discomfort.KeywordsPerson with visually impairmentLow visionLED blockVisibilitySensory test

With the booming development of green lighting technologies, ubiquitous lighting infrastructures make visible light positioning (VLP) become a promising technology for indoor localization and navigation. However, most existing VLP systems use modulated LEDs as anchors for target localization. LEDs with its customized hardware and modulated information greatly prevent VLP systems from large-scale deployment and limit their widespread applications. Moreover, some VLP systems have the disadvantage of imposing strong restrictions on smartphone such as fixed phone orientation, which is not practical for real-life use. In this paper, we propose a ubiquitous visible light localization (LiLoc) algorithm using ambient lights based on augmented particle filter algorithm. LiLoc directly uses the light intensity fingerprint of ambient light sources (e.g., fluorescent, incandescent, and LEDs) to estimate target location without obtaining modulation information of light sources in buildings. To improve localization accuracy, we introduce a light-intensity trajectory fingerprint matching scheme to calibrate target position. We also develop a beacon identification algorithm based on the inherent visual features of light sources, which are determined by specific manufacturing variations. We combine beacon identification algorithm with PDR to estimate target position in terrible illumination environment (e.g., sunlight interference, beacons sparse deployment, individual beacon damaged/closed, or training fingerprint missing).To reduce power consumption, we design adaptive scheduling mechanism to invoke corresponding algorithms based on the detection result of sunlight interference. The experimental results demonstrate that LiLoc can achieve medium localization errors of 2.2 m in a complex lighting environment with various light sources and sunlight interference.

Introduction Current guidance on office lighting tends to be oriented towards illumination engineering, i.e. achieving a certain lighting environment. The selection of lamps and luminaires from a vast array of current lighting options, as well as their layout, often reflects architectural style and energy efficiency, rather than ‘healthy’ lighting – which aims to eliminate or minimise adverse health effects, including visual discomfort, arising from visual tasks and ambient light sources. Methods Firstly, this paper explores the criteria for healthy lighting based on visual anatomy and pathophysiology and characteristics of workers and tasks in office environments. Secondly, survey methods addressing characteristics of light entering the eye are reviewed in the context of outcomes ranging from discomfort to retinal degradation. Results A primary consideration is characterisation of light sources in the occupational visual field, (OVF) which is mainly determined by the visual tasks. Another consideration is how, and for how long, the source(s) are imaged on the retina (especially the macula). Again this depends on the visual requirements of the task. Indeed, directionality is much more important for lighting than other hazards such as noise. Such assessments are not possible with an integrating light measuring instrument such as a lux metre. Finally, in the cases of blue-rich sources, the assessment should be more about radiometry than photometry. Discussion A variety of visual, circadian rhythm and psychological disturbances may arise from inappropriate lighting. The concept of ‘healthy’ lighting serves to integrate the issues, and surveys of lighting should begin with the OVF and systematic consideration of light sources therein. Assessment should involve luminance and where necessary radiance.

タスク・アンビエント照明における影の中の照度変化について

光源配光を変化させたタスク・アンビエント照明における影の中の照度変化について

We examined the characteristics of shadows created by task ambient lighting mounted on a ceiling on a work surface (a desk) for various combinations of lighting arrangements and luminous fluxes. Shadowing in work areas has become of greater concern with the decrease in illuminance on work surfaces due to the obstructions created by modern office designs (e. g., room partitions).We found that when the arrangement and flux produce an illuminance uniformity ratio of greater than 0.7, the maximum shadow factor is less than 0.6, and the areas in shadow are less than 15% of the total area. Application of this principle will enable the design of more comfortable and efficient offices.

This paper proposes a method for estimating the omnidirectional distribution of the scene illuminant spectrum from images taken by a camera aimed at a mirrored ball. First, we introduce measuring systems using a RGB color camera and a mirrored ball placed at an arbitrary location in a natural scene for acquiring ambient light from any direction. Second, in order to estimate the direction from which light comes to the ball, we calibrate the measuring systems and determine a mapping between the image coordinates of the spherical ball and the directions of light rays in the world. An omnidirectional image representing the spatial distribution of ambient light sources is created in a polar coordinate system. Third, we present an algorithm for recovering the illuminant spectral power distribution from the image data at each pixel and the reflectance data of the mirrored ball. Finally, we execute an experiment in a natural environment with multiple light sources for examining the feasibility of the proposed method.

When it is difficult to apply the methodology established in the GUM to calculate uncertainty in a measurement, the Monte Carlo method can be used to find an estimate of uncertainty. In this work, the Monte Carlo methodology was applied to find the uncertainty in luminous flux, when it is measured by means of a far-field goniophotometer. The methodology was applied on three light intensity matrices from three LED sources. The maximum uncertainty found is 1.2 % with a confidence level of approximately 95.5 %. By means of mathematical calculation and simulation it was determined that the distance between the light source and the sensor is the parameter that most influences the uncertainty in luminous flux.