Field Luminance Mapping of the Sky

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IES Annual Conference 2010—When sky luminance distributions are measured far from a laboratory facility, portable and inexpensive instruments are useful. High dynamic range (HDR) photography has become a practical method for sky luminance mapping. However, long exposure photography directed at the sun can cause severe damage to digital camera sensors. To avoid this problem, a system was designed that integrates an adjustable shading disk with an HDR camera. Simultaneous global horizontal illuminance measurements indirectly provide luminance data for the area of the sky that is occluded by the shading disk. In tests, the system presented here has achieved relative errors for the zenith luminance of approximately 10%. An integrated shading disk for an illuminance meter also is presented that allows diffuse horizontal illuminance measurements to be easily performed.

Authors: Konstantinos Papamichael, Ph.D; Luís Lomelino Fernandes, Ph.D; Anothai Thanachareonkit, Ph.D

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