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Proceedings of BSO Conference 2016: Third Conference of IBPSA-England

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Measuring Light Through Trees For Daylight Simulations: A Photographic And Photometric Method

Priji Balakrishnan, J. Alstan Jakubiec

Abstract: Trees play a significant role in influencing daylight availability inside and outside buildings. They temper, scatter and transmit light subsequently reducing the availability or acting as a passive source of daylight. Current daylighting simulation practices either avoid modelling trees or model them as cones, spheres or cylinders with an assumed reflectance value. Trees are complex in their shape and—depending on crown density and clumping nature—their optical properties change considerably. In order to predict the effect of trees on daylight, researchers need to first measure and quantify this effect. Hence, in this paper the authors propose a low-cost method employing high dynamic range photography and automated image processing to measure two variables of the tree crown: gap percentage and transmittance percentage. These measured variables can be used in daylight simulation platforms such as Radiance to geometrically model the crown of a tree and specify its optical properties
Pages: 114 - 121
Paper:
bso2016_1152