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Proceedings Paper

Measurements of the effect of falling snow on imaging with infrared cameras
Author(s): Arthur D. van Rheenen; Lars T. Heen; Eirik B. Madsen; Erik Brendhagen; Kjell Wikan
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Paper Abstract

We present results from imaging experiments performed in Norway during the 2005/06 winter season. Pairs of infrared sources with different temperatures are placed at different distances, ranging from 50 to 1200 m, from two focal plane array infrared cameras. One of the cameras is sensitive in the 3-5 μm wavelength range and the other in the 8-10 μm wavelength range. During the winter months digital sequences of the IR-sources were recorded, under different meteorological conditions. These conditions ranged from perfectly clear, cloudless weather to heavy snowfall. Analysis consists of comparing the perceived contrast, as measured with the cameras, with the "real" contrast as defined by the temperatures of the IR-sources. It is assumed that the transmission coefficient is the product of the atmospheric transmission (without snow) and a transmission factor associated with the falling snow. FASCODE simulations, using the pertinent temperature and humidity data that were measured during the recordings, are performed to characterize the atmospheric transmission coefficient (without snow). A comparison of the experimental results and the simulation results allows one then to estimate the effect of the falling snow on the extinction coefficient or visibility range. We observed a strong negative correlation between visibility and precipitation rate and better visibility in the MWIR range than in the LWIR range.

Paper Details

Date Published: 5 October 2006
PDF: 9 pages
Proc. SPIE 6395, Electro-Optical and Infrared Systems: Technology and Applications III, 639507 (5 October 2006); doi: 10.1117/12.689699
Show Author Affiliations
Arthur D. van Rheenen, Norwegian Defense Research Establishment (Norway)
Lars T. Heen, Norwegian Defense Research Establishment (Norway)
Eirik B. Madsen, Norwegian Defense Research Establishment (Norway)
Erik Brendhagen, Norwegian Defense Research Establishment (Norway)
Kjell Wikan, Norwegian Defense Research Establishment (Norway)

Published in SPIE Proceedings Vol. 6395:
Electro-Optical and Infrared Systems: Technology and Applications III
Ronald G. Driggers; David A. Huckridge, Editor(s)

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