Previous work has investigated light loss and illuminance distribution in obstructed interiors and put forward the use of 'standard obstructions' as a tool for classification of obstruction.Obstructions may be described for light loss purposes by the ratio of their vertical surface area to the floor area of the interior (VFR), which in practice must be either calculated or estimated. These can be dificult processes to apply to obstruction configurations other than simple rectilinear objects such as standard obstructions. This paper introduces photogrammetry as a tool for modelling obstructions and indicates potential uses of the method in lighting. Two case studies demonstrate the applicability of photogrammetry to modelling obstructions and hence lighting loss. The results confirm that this technology will accelerate the incorporation the effect of obstructions in lighting analysis and design.
Illuminance conditions in real interiors are influenced by obstructions such as furniture or machinery located between luminaires and the working plane. Investigations based on electrically lit offices have shown relationships between the various geometric and photometric parameters of general lighting installations and magnitude of working state light loss caused by furniture. This paper investigates the influence of obstruction height, vertical and horizontal surface area, and luminaire type on working plane illuminance characteristics and light losses. The results are applicable to a much wider range of interiors than studied hitherto including industrial type interiors that differ markedly from offices in building scale, type of obstruction and lighting equipment.
Photogrammetry methods have been shown to be useful as a tool for investigation of illuminance distribution and light losses in interiors containing obstruction con gurations that approximate to simple rectilinear objects. This work examines the use of photogrammetry to model obstructions having a greater degree of complexity and a case study demonstrates the applicability of the technique to lighting design for a factory. The results con rm that this technology would accelerate the process of incorporating the effect of obstructions in routine lighting analysis and design.
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