Measuring Light Pollution with a Calibrated High Dynamic Range All-Sky Image Acquisition System

Georg Zotti
Measuring Light Pollution with a Calibrated High Dynamic Range All-Sky Image Acquisition System
In DARKSKY2007 - 7th European Symposium for the Protection of the Night Sky. October 2007.
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Abstract

Combining series of exposures with different exposure times made with a digital SLR camera and a fish-eye lens allow to create high-resolution images that contain the full dynamic range of daylight, including the Sun, usable as scene background and for skylight illumination computation purposes. These High Dynamic Range (HDR) images can also be calibrated with a luminance meter, so the image data contain meaningful values, and the system becomes a measuring device. At night, long-time exposures can be combined, and the setup, once fine-calibrated with a Sky Quality Meter or another low-level light measuring device, becomes a valuable tool to provide absolute values of sky brightness. Using data from the astronomical literature, false-colour plots of sky luminance can be created that closely match visual estimation of visible stellar magnitudes.

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@inproceedings{zotti-2007-hdr,
  title =      "Measuring Light Pollution with a Calibrated High Dynamic
               Range All-Sky Image Acquisition System",
  author =     "Georg Zotti",
  year =       "2007",
  abstract =   "Combining series of exposures with different exposure times
               made with a digital SLR camera and a fish-eye lens allow
               to create high-resolution images that contain the full
               dynamic range of daylight, including the Sun, usable as
               scene background and for skylight illumination computation
               purposes. These High Dynamic Range (HDR) images can also be
               calibrated with a luminance meter, so the image data contain
               meaningful values, and the system becomes a measuring
               device. At night, long-time exposures can be combined, and
               the setup, once fine-calibrated with a Sky Quality Meter
               or another low-level light measuring device, becomes a
               valuable tool to provide absolute values of sky brightness.
               Using data from the astronomical literature, false-colour
               plots of sky luminance can be created that closely match
               visual estimation of visible stellar magnitudes.",
  pages =      "%pages_from%--%pages_to%",
  month =      oct,
  address =    "Bled",
  booktitle =  "DARKSKY2007 - 7th European Symposium for the Protection of
               the Night Sky",
  editor =     "Andrej Mohar",
  location =   "Bled",
  keywords =   "HDR imaging, Light Pollution, Skylight",
  URL =        "http://www.cg.tuwien.ac.at/research/publications/2007/zotti-2007-hdr/",
}