Abstract

For elimination of the shortcomings of imaging polarimeters that take the necessary three pictures sequentially through linear-polarization filters, a three-lens, three-camera, full-sky imaging polarimeter was designed that takes the required pictures simultaneously. With this polarimeter, celestial polarization patterns can be measured even if rapid temporal changes occur in the sky: under cloudy sky conditions, or immediately after sunrise or prior to sunset. One of the possible applications of our polarimeter is the ground-based detection of clouds. With use of the additional information of the degree and the angle of polarization patterns of cloudy skies measured in the red (650 nm), green (550 nm), and blue (450 nm) spectral ranges, improved algorithms of radiometric cloud detection can be offered. We present a combined radiometric and polarimetric algorithm that performs the detection of clouds more efficiently and reliably as compared with an exclusively radiometric cloud-detection algorithm. The advantages and the limits of three-lens, three-camera, full-sky imaging polarimeters as well as the possibilities of improving our polarimetric cloud detection method are discussed briefly.

© 2002 Optical Society of America

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References

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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  8. I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
    [PubMed]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  13. HNP’B, Polaroid Europe Ltd., London, England, http://www.polaroid.com .
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  15. K. L. Coulson, Polarization and Intensity of Light in the Atmosphere (A. Deepak, Hampton, Va., 1988).
  16. N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).
  17. F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).
  18. P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
    [CrossRef]

2001 (6)

J. Gál, G. Horváth, V. B. Meyer-Rochow, “Measurement of the reflection-polarization pattern of the flat water surface under a clear sky at sunset,” Remote Sens. Environ. 76, 103–111 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
[PubMed]

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

1997 (3)

1994 (1)

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

1993 (1)

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

1988 (1)

R. W. Saunders, K. T. Kriebel, “An improved method for detecting clear sky and cloudy radiances from AVHRR data,” Int. J. Remote Sens. 9, 123–150 (1988).
[CrossRef]

1986 (1)

R. W. Saunders, “An automated scheme for the removal of cloud contamination from AVHRR radiances over western Europe,” Int. J. Remote Sens. 7, 867–886 (1986).
[CrossRef]

Barta, A.

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

Bernáth, B.

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

Coulson, K. L.

K. L. Coulson, Polarization and Intensity of Light in the Atmosphere (A. Deepak, Hampton, Va., 1988).

Cronin, T. W.

N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).

Derrien, M.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Deuzé, J. L.

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

Duggin, M. J.

Farki, B.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Fouquart, Y.

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

Gál, J.

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, “Measurement of the reflection-polarization pattern of the flat water surface under a clear sky at sunset,” Remote Sens. Environ. 76, 103–111 (2001).
[CrossRef]

Goloub, P.

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

Harang, L.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Herman, M.

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

Horváth, G.

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, “Measurement of the reflection-polarization pattern of the flat water surface under a clear sky at sunset,” Remote Sens. Environ. 76, 103–111 (2001).
[CrossRef]

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
[PubMed]

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

Johnson, G.

N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).

Können, G. P.

G. P. Können, Polarized Light in Nature (Cambridge U. Press, Cambridge, 1985).

Kriebel, K. T.

R. W. Saunders, K. T. Kriebel, “An improved method for detecting clear sky and cloudy radiances from AVHRR data,” Int. J. Remote Sens. 9, 123–150 (1988).
[CrossRef]

Kriska, G.

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

LeGléau, H.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Liu, Y.

Meyer-Rochow, V. B.

J. Gál, G. Horváth, V. B. Meyer-Rochow, “Measurement of the reflection-polarization pattern of the flat water surface under a clear sky at sunset,” Remote Sens. Environ. 76, 103–111 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

Mizera, F.

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

North, J. A.

Noyalet, A.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Pochic, D.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Pomozi, I.

I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
[PubMed]

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

Sairouni, A.

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Saunders, R. W.

R. W. Saunders, K. T. Kriebel, “An improved method for detecting clear sky and cloudy radiances from AVHRR data,” Int. J. Remote Sens. 9, 123–150 (1988).
[CrossRef]

R. W. Saunders, “An automated scheme for the removal of cloud contamination from AVHRR radiances over western Europe,” Int. J. Remote Sens. 7, 867–886 (1986).
[CrossRef]

Shashar, N.

N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).

Voss, K. J.

Wehner, R.

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
[PubMed]

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

Wolff, L. B.

N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).

Appl. Opt. (3)

IEEE Trans. Geosci. Remote Sens. (1)

P. Goloub, J. L. Deuzé, M. Herman, Y. Fouquart, “Analysis of the POLDER polarization measurements performed over cloud covers,” IEEE Trans. Geosci. Remote Sens. 32, 78–88 (1994).
[CrossRef]

Int. J. Remote Sens. (2)

R. W. Saunders, “An automated scheme for the removal of cloud contamination from AVHRR radiances over western Europe,” Int. J. Remote Sens. 7, 867–886 (1986).
[CrossRef]

R. W. Saunders, K. T. Kriebel, “An improved method for detecting clear sky and cloudy radiances from AVHRR data,” Int. J. Remote Sens. 9, 123–150 (1988).
[CrossRef]

J. Exp. Biol. (1)

I. Pomozi, G. Horváth, R. Wehner, “How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation,” J. Exp. Biol. 204, 2933–2942 (2001).
[PubMed]

J. Geophys. Res. D (1)

J. Gál, G. Horváth, A. Barta, R. Wehner, “Polarization of the moonlit clear night sky measured by full-sky imaging polarimetry at full moon: comparison of the polarization of moonlit and sunlit skies,” J. Geophys. Res. D 106, 22647–22653 (2001).
[CrossRef]

J. Imaging Sci. Technol. (1)

F. Mizera, B. Bernáth, G. Kriska, G. Horváth, “Stereo videopolarimetry: measuring and visualizing polarization patterns in three dimensions,” J. Imaging Sci. Technol. 45, 393–399 (2001).

Proc. R. Soc. Lond. Ser. A (1)

J. Gál, G. Horváth, V. B. Meyer-Rochow, R. Wehner, “Polarization patterns of the summer sky and its neutral points measured by full-sky imaging polarimetry in Finnish Lapland north of the Arctic Circle,” Proc. R. Soc. Lond. Ser. A 457, 1385–1399 (2001).
[CrossRef]

Remote Sens. Environ. (3)

J. Gál, G. Horváth, V. B. Meyer-Rochow, “Measurement of the reflection-polarization pattern of the flat water surface under a clear sky at sunset,” Remote Sens. Environ. 76, 103–111 (2001).
[CrossRef]

I. Pomozi, J. Gál, G. Horváth, R. Wehner, “Fine structure of the celestial polarization pattern and its temporal change during the total solar eclipse of 11 August 1999,” Remote Sens. Environ. 76, 181–201 (2001).
[CrossRef]

M. Derrien, B. Farki, L. Harang, H. LeGléau, A. Noyalet, D. Pochic, A. Sairouni, “Automatic cloud detection applied to NOAA-11/AVHRR imagery,” Remote Sens. Environ. 46, 246–267 (1993).
[CrossRef]

Other (5)

HNP’B, Polaroid Europe Ltd., London, England, http://www.polaroid.com .

G. P. Können, Polarized Light in Nature (Cambridge U. Press, Cambridge, 1985).

K. L. Coulson, Polarization and Intensity of Light in the Atmosphere (A. Deepak, Hampton, Va., 1988).

N. Shashar, T. W. Cronin, G. Johnson, L. B. Wolff, “Designs for submersible imaging polarimeters,” Ultraviolet Radiation and Coral Reefs, D. Gulko, P. L. Jokiel, eds., HIMB Tech. Report41, 213–218 (1996).

Description of the TSI-880 Total Sky Imager, Yankee Environmental Systems, Inc., Airport Industrial Park, 101 Industrial Blvd., Turners Falls, Mass. 01376; http://www.yesinc.com ; e-mail, info@yesinc.com.

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Figures (12)

Fig. 1
Fig. 1

Setup of our three-lens, three-camera, full-sky (180° field-of-view) imaging polarimeter.

Fig. 2
Fig. 2

Sigma fish-eye lens in the mounted (a) and dismounted (b) state used in our polarimeter.

Fig. 3
Fig. 3

Direction of the preferred transmission axis of the built-in linear polarization filters in our polarimeter.

Fig. 4
Fig. 4

Blocking of the direct solar radiation by a sun occulter held by an assistant to eliminate multiple internal reflections at the refracting surfaces within the fish-eye lenses of our polarimeter.

Fig. 5
Fig. 5

(a) Three-dimensional celestial polar coordinate system. (b) Two-dimensional celestial system of polar coordinates used in the circular sky photographs. East is on the left (rather than on the right) of the compass rose because the view is up through the celestial dome rather than down onto a map.

Fig. 6
Fig. 6

(a) Relationship between the projection angle θ p (projected onto the photoemulsion by the fish-eye lens) and the off-axis angle θ o . The broken line represents the ideal case when θ p = θ o . (b, c) Change of the elements m 12 and m 13 of the reduced Mueller matrix of the fish-eye lens without polarizer as a function of θ o .

Fig. 7
Fig. 7

Photograph and the patterns of the degree of linear polarization p and angle of polarization α of a sky with fast-moving cumuli measured by our three-lens, three-camera, full-sky imaging polarimeter in simultaneous mode in the red (650 nm), green (550 nm), and blue (450 nm) spectral ranges at Kunfehértó (46° 23′ N, 19° 24′ E, Hungary) on 15 August 2000 at 17:00 (local summer time = UTC + 2). The overexposed regions of the sky around the sun and the underexposed regions of the sky at about 90° from the sun as well as the sun occulter are checkered in the p and α patterns.

Fig. 8
Fig. 8

Same as Fig. 7 for a clear, cloudless sky with the same solar position at Kunfehértó (46° 23′ N, 19° 24′ E, Hungary) on 17 August 2000 at 17:00 (local summer time = UTC + 2).

Fig. 9
Fig. 9

(a) Photograph (identical with that in the first row of Fig. 7) of the partially cloudy sky, the polarization characteristics of which are shown in Fig. 7. (b) Cloudy (white) and clear (black) sky regions detected visually by the naked eye in (a). (c) Clouds detected radiometrically, where the under- or overexposed celestial areas are checkered as the sun occulter. PCC, proportion of cloud cover determined by the different detectors IRGB, PR, PG, PB, αR, αG, and αB; PSDC, proportion of (clear) sky detected (erroneously) as cloud; PCDS, proportion of clouds detected (erroneously) as (clear) sky; PUO, proportion of under- and/or overexposure.

Fig. 10
Fig. 10

Clouds detected polarimetrically in the red (650 nm), green (550 nm), and blue (450 nm) spectral ranges with the degree or angle of polarization patterns in Figs. 7 and 8. Other conventions as in Fig. 9.

Fig. 11
Fig. 11

(a) Gray-coded map of the number n of cloud identification calculated for the partially cloudy sky in Fig. 9(a), the optical characteristics of which are shown in Fig. 7. (b) Gray-coded map of the number m of active (neither underexposed nor overexposed) detectors calculated for the partially cloudy sky in Fig. 9(a). m is proportional to the authenticity of the (cloud or clear sky) detection. The under- or overexposed sky regions (m = 0) as well as the sun occulter in the maps are checkered.

Fig. 12
Fig. 12

(a) Map combining maps a and b in Fig. 11. At a given value of m, the value of n/ n max(m) is the likelihood of cloud, while 1 - n/ n max(m) is the likelihood of clear sky. (b) Cloudy (white) and clear (black) sky regions detected by the combined (radiometric and polarimetric) algorithm such that pixels with larger or smaller n(m) values than n(m)* were considered to belong to clouds or clear sky regions, respectively. For n(2)* = 1, n(4)* = 3, and n(9)* = 5 (the positions of which are indicated by white vertical bars in the gray palette) the proportion of erroneous detection PED = PCDS + PSDC is minimal (PED* in Table 1). The under- or overexposed sky regions (m = 0) as well as the sun occulter in the maps are checkered.

Tables (3)

Tables Icon

Table 1 Optimal Values of the Control Parameters of the Different Cloud-Detection Algorithms (Detectors in Figs. 9 and 10) that Minimize the Proportion of Erroneous Detection (PED*)

Tables Icon

Table 2 Threshold Values n(m)* of the Number n(m) of Cloud Identification of the Polarimetric and Combined (Radiometric and Polarimetric) Cloud-Detection Algorithms as a Function of the Number m of Active Detectorsa

Tables Icon

Table 3 Numerical Values of the Proportion of Cloud Cover Detected by the Radiometric, Polarimetric, and Combined (Radiometric and Polarimetric) Cloud-Detection Algorithmsa

Metrics