A new methodology for calculating roadway lighting design based on a multi-objective evolutionary algorithm

This paper presents a new method for calculating the design of roadway lighting. Apart from its accuracy, this method, which is based on a multi-objective evolutionary algorithm, has the added advantage of enhancing the energy efficiency of lighting installations. This is positive because the economic use of energy resources is evidently a priority in the world today. In our study, an exhaustive calibration process was used to fine-tune the accuracy and precision of the new method presented. The results obtained were then compared with those of DIALUX, a well-known free software program that is frequently used for the design of lighting installations. In the second phase of this research, the lighting installation was made more complex in order to verify the applicability of this new method to a wide range of different contexts.     

Inverse lighting design for interior buildings integrating natural and artificial sources

In this paper we propose a new method for solving inverse lighting design problems that can include diverse sources such as diffuse roof skylights or artificial light sources. Given a user specification of illumination requirements, our approach provides optimal light source positions as well as optimal shapes for skylight installations in interior architectural models. The well known huge computational effort that involves searching for an optimal solution is tackled by combining two concepts: exploiting the scene coherence to compute global illumination and using a metaheuristic technique for optimization.Results and analysis show that our method provides both fast and accurate results, making it suitable for lighting design in indoor environments while supporting interactive visualization of global illumination.     

User interaction with everyday lighting systems

New lighting technologies create new opportunities that may contribute to people’s experience of light. These opportunities are a result of the increased variety and freedom in terms of colour, form factor and connectivity of the lights. To allow people to fully benefit from the potential of such novel lighting systems, there is a need for a new user interaction paradigm. To develop this paradigm, we have to better understand the aspects that play a part in the interaction with lighting, paying special attention to people’s motivation for interaction. This paper reports on a context-mapping study that was performed to gain insight in these aspects. As result, we present a set of seven themes that regard the interaction with lighting in the current situation and in the future. These themes provide an overview of the relevant aspects in this domain and contain considerations and opportunities for the design of new interfaces for novel lighting systems. We conclude that people have different levels of lighting needs that are highly dependent on context and that also require control at different levels. The context and lighting needs have a large influence on the extent to which people are motivated to adjust their lighting. Moreover, the lighting interface itself has a large effect on this motivation, mainly influenced by the degrees of freedom, the control location and availability, the degree of automation and general interaction qualities.     

Composite lighting simulations with lighting networks

Lighting networks combine different global illumination algorithms in a composite lighting simulation and allow for restricting costly lighting effects to important parts of the scene. In the lighting networks approach, each lighting algorithm is considered a lighting operator or LightOp. Each LightOp takes illumination information as input and generates new illumination information as output after having simulated part of the global lighting effects in the scene. We motivate the use of LightOps from the formal solution of the radiance equation. We then demonstrate how these LightOps can easily combine into a lighting network, representing a composite lighting simulation     

Advances in automotive interior lighting concerning new LED approach and optical performance

Automotive interior lighting has to follow general trends in lighting and will therefore evolve toward hundreds and even thousands of RGB LEDs per car. Creating mood at day and night, pixelated sign‐like information, and theater‐like effects like welcome and goodbye messages are examples for outstanding user experience. Furthermore, safety features such as warnings and driving state are a must for autonomous cars. It requires new concepts for the whole interior lighting system to reach premium quality such as data rate (beyond today's bus standard for lighting), support for safety rules, compensation of temperature effects, daylight performance (including huge dimming range for night drive), uniformity in terms of luminance and color along the light guide, and mixing of red, green, and blue (RGB) with white. We report a new automotive RGB light‐emitting diode (LED) system that fulfills the above requirements and saves effort as well as cost by calibration before integration. Extensive studies were performed for daylight threshold evaluation with subjects and methods for judging on uniformity for direct‐lit RGB light guides based on the contrast sensitivity function and Gaussian fit of the LED luminance profile.     

基于RF4CE的LED照明调控系统

为了克服现有DALI、C-Bus等照明控制系统在开放性、可靠性、安全性、设备及运行成本等方面存在的不足,依据RF4CE射频遥控标准,设计了一套LED智能照明系统。该系统可通过人机界面设置期望的光强、色温及特殊照明效果,当遥控器将控制需求发送到各LED调光器后,可由调光器自动完成LED工作状态的调控,以组成用户所需的照明环境,并达到节能降耗的效果。     

Effect of task and eccentricity of the target on detection thresholds in mesopic vision: implications for road lighting

OBJECTIVE: The aim of this work is to assess how adding a driving-related task affects the detection of objects in peripheral vision, under mesopic conditions. BACKGROUND: The main index used to assess the quality of road lighting installations refers to simple detection tasks in foveal vision, which raises methodological and practical questions. METHOD: The experimental design consisted of a three-phase experiment. In the first phase, two groups (control and experimental) performed a peripheral detection task (simple task). Based on these results an individual detection threshold was computed for each participant and eccentricity. A tracking task was performed in Phase 2 for both groups (steering a tracking target along a circuit, on a screen). In the third phase, the control group performed the same task as in Phase 2. The experimental group performed a double task, with a tracking (primary) task and a peripheral detection (secondary) task. RESULTS: The data show an effect of the tracking task and eccentricity on peripheral event detection. The tracking task caused detection performance to decrease from 84.2% to 67.5%, p < .001. CONCLUSION: The small target visibility model used in road lighting may be improved, taking into account the effects of task and eccentricity on target detection. APPLICATION: This study supports improved roadway lighting design by guiding consideration of sign eccentricity and task load.     

Effects of virtual lighting on visual performance and eye fatigue

This study is designed to determine whether differences in eye fatigue and visual performance can be shown under varying virtual industrial lighting conditions. It is based on the results of studies of more traditional video display terminal (VDT) tasks reported in the literature. One experiment was designed to determine if the effects of virtual lighting on eye fatigue and visual performance in a simulated virtual industrial environment are similar to some other VDT tasks with varying luminance contrast. Results of a test of 20 participants in a vigilance task show that there is a significant difference in performance and eye fatigue in the virtual environment with varying virtual light conditions. These results may help designers see that performance in some virtual “lighting” conditions, for some tasks, is consistent with that in the real. However, due to the difficulties of determining the appropriate virtual objects to be considered for the luminance measures, additional research is needed to be able to generalize the results to other industrial training scenarios. A second experiment was intended to test for the luminance decrement in a VDT that was shown in recent literature. The results would have potential implications for the experiment that included a vigilance task. However, the results showed that the luminance decrement demonstrated in recent literature did not occur. These results suggest that the equipment used in the present experiments should not cause difficulty in interpreting the results of the vigilance task. © 2002 Wiley Periodicals, Inc.     

Ergonomics and lighting

The two main principles of ergonomics can be said to 'fit the job to the man', or 'fit the man to the job'. To a high extent this is really valid for lighting ergonomics. If an employee complains that he (or she) cannot see properly what he is doing in his work it could be adjusted either by improving the job itself or by improving the visual capacity of the person in question (eg, prescribing correct work glasses). If improving measures are not taken local eye discomfort may develop with symptoms as fatigue, ache, pain, burning, pulling, tearing, etc. These symptoms make up a syndrome called asthenopia, otherwise succinctly known as eye strain. The causes of the syndrome can be myriad - but all fall in under the headings 'bad' lighting, 'bad' eyes and 'bad' work.     

基于无线传感器网络的隧道照明控制系统

针对当前隧道照明控制系统在节能性和安全稳定性上的一些不足,设计了一种新的基于无线传感器网络的隧道照明控制系统,建立了系统的总体架构。系统以Zig Bee模块CC2530为无线传感器节点核心,将各节点采集的车流量和洞内亮度等信息处理后传输到远程监控计算机。对系统的电源电路、调试器电路、RS—232接口电路进行了设计,完成了相应的软件控制系统。软件仿真和数学分析表明:该系统能有效地控制光线的连续性,节能效果良好。     

Inverse compositional estimation of 3D pose and lighting in dynamic scenes

In this paper, we show how to estimate, accurately and efficiently, the 3D motion of a rigid object and time-varying lighting in a dynamic scene. This is achieved in an inverse compositional tracking framework with a novel warping function that involves a 2D --> 3D --> 2D transformation. This also allows us to extend traditional two frame inverse compositional tracking to a sequence of frames, leading to even higher computational savings. We prove the theoretical convergence of this method and show that it leads to significant reduction in computational burden. Experimental analysis on multiple video sequences shows impressive speed-up over existing methods while retaining a high level of accuracy.     

Acquiring linear subspaces for face recognition under variable lighting

Previous work has demonstrated that the image variation of many objects (human faces in particular) under variable lighting can be effectively modeled by low-dimensional linear spaces, even when there are multiple light sources and shadowing. Basis images spanning this space are usually obtained in one of three ways: a large set of images of the object under different lighting conditions is acquired, and principal component analysis (PCA) is used to estimate a subspace. Alternatively, synthetic images are rendered from a 3D model (perhaps reconstructed from images) under point sources and, again, PCA is used to estimate a subspace. Finally, images rendered from a 3D model under diffuse lighting based on spherical harmonics are directly used as basis images. In this paper, we show how to arrange physical lighting so that the acquired images of each object can be directly used as the basis vectors of a low-dimensional linear space and that this subspace is close to those acquired by the other methods. More specifically, there exist configurations of k point light source directions, with k typically ranging from 5 to 9, such that, by taking k images of an object under these single sources, the resulting subspace is an effective representation for recognition under a wide range of lighting conditions. Since the subspace is generated directly from real images, potentially complex and/or brittle intermediate steps such as 3D reconstruction can be completely avoided; nor is it necessary to acquire large numbers of training images or to physically construct complex diffuse (harmonic) light fields. We validate the use of subspaces constructed in this fashion within the context of face recognition.     

Daylight,artificial light and people in an office environment,overview of visual and biological responses

Long-term behaviour /response of people has been studied in standard window zone offices during daytime working hours. Regular cell-offices were equipped with experimental lighting systems delivering lighting conditions that are known to influence human physiology. The results show that most people prefer to follow a daylight cycle instead of a constant level. Preferred lighting levels are significantly higher than today's indoor lighting standards and correspond to levels where biological stimulation can occur. The results strongly suggest that meeting biological lighting needs is very different from meeting visual needs. Results of two permanent occupants show striking differences in lighting settings, which correspond to individual circadian cycles and performance. This strengthens that present indoor lighting levels (and standards) are too low for biological stimulation. Medical research has shown that a prolonged lack of ‘light vitamin’ can cause health problems ranging from minor sleep and performance difficulties to major depressions. This inevitably suggests that ‘poor’ indoor lighting is the underlying cause of many of the health and performance problems. By naming this the ‘ill-lighting syndrome’ we may well have identified the fundamental mechanism that can result in many different negative health/performance effects. Creating healthy indoor lighting can be a simple form of preventive medicine and providing a new challenge for the lighting community.     

Spatially varying image based lighting by light probe sequences

We present a novel technique for capturing spatially or temporally resolved light probe sequences, and using them for image based lighting. For this purpose we have designed and built a real-time light probe, a catadioptric imaging system that can capture the full dynamic range of the lighting incident at each point in space at video frame rates, while being moved through a scene. The real-time light probe uses a digital imaging system which we have programmed to capture high quality, photometrically accurate color images of 512×512 pixels with a dynamic range of 10000000:1 at 25 frames per second. By tracking the position and orientation of the light probe, it is possible to transform each light probe into a common frame of reference in world coordinates, and map each point and direction in space along the path of motion to a particular frame and pixel in the light probe sequence. We demonstrate our technique by rendering synthetic objects illuminated by complex real world lighting, first by using traditional image based lighting methods and temporally varying light probe illumination, and second an extension to handle spatially varying lighting conditions across large objects and object motion along an extended path.     

A theory of frequency domain invariants: spherical harmonic identities for BRDF/lighting transfer and image consistency

This paper develops a theory of frequency domain invariants in computer vision. We derive novel identities using spherical harmonics, which are the angular frequency domain analog to common spatial domain invariants such as reflectance ratios. These invariants are derived from the spherical harmonic convolution framework for reflection from a curved surface. Our identities apply in a number of canonical cases, including single and multiple images of objects under the same and different lighting conditions. One important case we consider is two different glossy objects in two different lighting environments. For this case, we derive a novel identity, independent of the specific lighting configurations or BRDFs, that allows us to directly estimate the fourth image if the other three are available. The identity can also be used as an invariant to detecttampering in the images.While this paper is primarily theoretical, it has the potential to lay the mathematical foundations for two important practical applications. First, we can develop more general algorithms for inverse rendering problems, which can directly relight and change material properties by transferring the BRDF or lighting from another object or illumination. Second, we can check the consistency of an image, to detect tampering or image splicing.     

VISIBILITY IN LIGHTED STREETS AND THE EFFECT OF THE ARRANGEMENT AND LIGHT DISTRIBUTION OF THE LANTERNS∗

Abstract

This paper discusses the problem of assessing visibility in lighted streets find some inadequacies of existing lighting installations.

Two investigations are reported : the first on the effect on brightness and ‘ patchiness ’ of the spacing of lighting installations on roads of different widths. The second compares two cut-off and non-cutoff lighting installations in terms of visibility and glare.     

矿用电机车一体化LED照明系统设计

针对矿用电机车白炽灯照明系统存在照度低、射程近、易发生追尾事故、耗电量大的问题,提出了矿用电机车一体化LED照明系统的实现方案,详细介绍了LED照明灯、恒流源线路、模块化逆变电源、场效应管并联均流的设计要点。实际应用表明,该系统消除了矿用电机车运输中的安全隐患,解决了白色照明灯和红色尾灯一体化、逆变电源高压与低压分离的难题,耗电量低,节电效果好。     

Geometry-dependent lighting

In this paper, we introduce geometry-dependent lighting that allows lighting parameters to be defined independently and possibly discrepantly over an object or scene based on the local geometry. We present and discuss light collages, a lighting design system with geometry-dependent lights for effective feature-enhanced visualization. Our algorithm segments the objects into local surface patches and places lights that are locally consistent but globally discrepant to enhance the perception of shape. We use spherical harmonics for efficiently storing and computing light placement and assignment. We also outline a method to find the minimal number of light sources sufficient to illuminate an object well with our globally discrepant lighting approach.     

Total variation models for variable lighting face recognition

In this paper, we present the logarithmic total variation (LTV) model for face recognition under varying illumination, including natural lighting conditions, where we rarely know the strength, direction, or number of light sources. The proposed LTV model has the ability to factorize a single face image and obtain the illumination invariant facial structure, which is then used for face recognition. Our model is inspired by the SQI model but has better edge-preserving ability and simpler parameter selection. The merit of this model is that neither does it require any lighting assumption nor does it need any training. The LTV model reaches very high recognition rates in the tests using both Yale and CMU PIE face databases as well as a face database containing 765 subjects under outdoor lighting conditions.     

Adjustable beam lighting with LED matrix and lens array

An adjustable beam lighting solution is coming widely on demand for different applications with improved energy efficiency, reduced light pollution, or enriched decorative effects. A Matrix Lighting configuration, which mainly consists of a light‐emitting diode matrix and a lens array, is proposed as a promising adjustable beam lighting solution. It easily builds up the source‐target mapping based on the integral imaging principle, and it could adjust the light beam and shape freely and timely. The basic configuration, the general design rules with imaging optics, and the optimization approaches based on ray tracing were presented. An example lighting system consists of a 32 × 32 × RGB light‐emitting diode matrix, and the 8 × 8 Fresnel lens array is demonstrated, which accomplishes a localized lighting with addressable regions for power saving. It can also project colorful patterns on the ground or a wall for atmosphere heightening.