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Measuring Light Pollution with a Calibrated High Dynamic Range - - PowerPoint PPT Presentation
Measuring Light Pollution with a Calibrated High Dynamic Range - - PowerPoint PPT Presentation
Measuring Light Pollution with a Calibrated High Dynamic Range All-Sky Image Acquisition System Georg Zotti Institute of Computer Graphics and Algorithms Vienna University of Technology Outline Sky Luminance and Stellar Visibility High
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Sky Luminance and Stellar Visibility Instrument Vision Human Vision
[after Weaver 1947, Garstang 1986, Cinzano 1997]
Full Moon Sunset
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High Dynamic Range Photography
Combination of several exposures Calibration with Luminance Meter Luminance Map Photographic Measurement System
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Our System
Camera: Digital SLR
All-Sky Fisheye only with Full-Size Chip DSLRs RAW image format!
Free Software:
Dcraw for RAW image processing http://cybercom.net/~dcoffin/dcraw/ PFS Tools for HDR processing http://www.mpi-inf.mpg.de/resources/pfstools/
Extensible Calibration:
PFS Tools, from EXIF data (approximative) Minolta LS-110 for daylight range Sky Quality Meter for night measurements
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Evaluation of Zenith Luminance Series of HDR photos Averaged zenith area
Tonemapped HDR images
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Evaluation of Zenith Luminance
cd/m²
Sun alt.
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Evaluation of Zenith Luminance Illumination Reduction
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Results: Surburb Sky
Full illumination Reduced illumination
Difference on photographs hard to detect
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Results: Surburb Sky
Full illumination Reduced illumination
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Results: City Border (average)
Full illumination Reduced illumination
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Results: City Border (good night)
Full illumination Reduced illumination
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Results: City Border / 20km from Vienna
mag5 Good site near Vienna, mag6
Vienna
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Results: 20km from Vienna / Desert
Good site near Vienna, mag6 Desert Sky (Libya) mag6.5
Camp Vienna
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