In response to environmental concerns, demands for improved energy efficiency and a desire to create a more pleasant working environment; building designers are looking for ways to make better use of natural light. However, whilst natural light is both free and non-polluting, it can also produce high levels of visual contrast and glare, and unwanted heat. Most current design techniques estimate the natural internal illumination that results from an overcast sky; they do not include the contribution by direct sunlight entering the space, which is often the source of unwanted characteristics. Whilst a sophisticated computer ray-tracing program (RADIANCE) exists that can predict the full range of natural illumination, each prediction can take several minutes (or longer) to calculate. The time required to examine how a natural lighting design behaves over a typical year can therefore be prohibitive. Techniques for estimating the illumination provided by artificial lights also predict illumination under static conditions. Current techniques are therefore unsuitable for examining the dynamic behaviour of a lighting design, which links the automatic control of artificial lights to the changing levels of natural light. The aim of this research was to develop a computer based lighting design tool that overcomes these limitations. Based on the calculation of lighting coefficients, the numeric relationship between the luminance of light sources and the illuminance they produce, the Dynamic Lighting System (DLS) is able to calculate time-varying illuminance from a combination of natural light and artificial lights controlled by a lighting control system. The DLS has been written using the platform independent programming language Java. It is therefore able to run unaltered on most computer platforms, although in practice is limited to platforms on which the ray-tracing program RADIANCE will run, as RADIANCE is used to calculate coefficients. The DLS has been tested by comparing predicted levels of illuminance with levels measured in a test room under real sky conditions. These comparisons showed a high degree of correlation, but with a few large discrepancies. Possible causes of these discrepancies are offered and suggestions made about how they might be eliminated.

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This project examines the role of daylight and illumination in the design of urban public space. It explores the 'civic urban public space' in its form as well as its social, health, economic and economic value. It also explores past and present studies in light psychology. Lastly this project examines the history of light - from sun celebration and ritual to the rise of public illumination. The site design proposes one way in which light can enhance the identity, use and health of a plaza in the City of Langley. It emphasizes that plaza design must combine an innovative use of daylight and shadow, as well as illumination. The proposed design uses cycles of the sun and shadow, multifunctional use of illumination, and a variety of light levels and elements. The design aspires to reduce light pollution, demonstrate sustainable technologies and enhance 'sense of community'.

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This paper investigates two distinct, but related, topics in machine vision. The first is the effect of lighting on the performance of a 2D vision-based inspection system. The lighting component of machine vision has often been overlooked; an attempt was made to quantify the impact on existing machine vision algorithms. The second topic explores the applications of a data-rich 3D vision sensor that is capable of providing depth data in a wide range of ambient lightning conditions for industrial applications. A focus is placed on inspection systems with the depth data provided by the sensor. Three basic lighting geometries were compared quantitatively based on discriminant analysis in an inspection task that checked for the presence of J-clips on an aluminum carrier. Two different LabVIEW® machine vision algorithms were used to evaluate backlight, bright field and dark field illumination on their ability to minimize the span of the pass (clip present) and fail (clip absent) sample sets, as well as maximize the separation between these sample sets. Results showed that there were clear differences in performance with the different lighting geometries, with over a 30% change in performance. Although it has long been accepted that the choice of lighting for machine vision systems is not a trivial exercise, this paper provides a quantitative measure of the impact lighting has on the performance of feature-based machine vision. The Microsoft Kinect® is a commercial vision sensor that can simultaneously provide a colour video stream, comparable to current webcam technologies, in addition to a depth stream that provides three-dimensional information of the camera’s field of view and is invariant to environmental lighting. An experiment was carried out to characterize the sensor’s accuracy and precision, and to evaluate its performance as an inspection system to determine the orientation of a wheel. Tests were also conducted to determine the effect that changes in the physical environment had on performance. These changes included camera height, lighting and surface material. Results of the experiment have shown that the sensor has an average precision of ±0.12 cm and average accuracy of 0.5 cm, both with less than a 30% change when varying physical features. A discriminant analysis was performed to measure inspection performance, which showed less than 30% change with set separation, but not for set span. No trends were apparent with the change in set span relating to the change in physical features. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-02-29 18:33:20.505

The objective of this project is to design a facility that will characterize the electrical and optical properties of both tubular and the more recent compact fluorescent tubes. The first stage of this project, which is the subject of this dissertation, was to design, build, test, and model a cylindrical light integrating chamber. An integrating chamber capable of measuring 2-metre long fluorescent tubes was built at the University of KwaZulu-Natal, South Africa. To approximate an infinitely long tube, precisely mounted planar mirrors were placed at opposite ends of the cylinder. The reflectance of diffusive reflective paint and mirrors enter into calculations and were investigated experimentally using a Jarrel-Ash optical spectrometer. The light flux was finally measured for various chamber lengths and compared with a mathematical model. Total light power output from the lamp was calculated and compared with the electrical power input, and the lamp efficiency deduced. Accurate calculations required that the light field surrounding a cylindrical diffuse source be modeled mathematically. The reflection coefficients of the mirrors were not unity and the equations had to be modified to include this effect. The mathematical model was solved using a combination of analytical and numerical techniques. The model results were compared with measurements. The final result includes a mathematical description of the integrating chamber, and a flux-density plot of the space surrounding the fluorescent tube. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

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