https://atmos.meteo.uni-koeln.de/ag_crewell/ 2026-04-14T15:13:52+00:00 https://atmos.meteo.uni-koeln.de/ag_crewell/ https://atmos.meteo.uni-koeln.de/ag_crewell/lib/exe/fetch.php?media=wiki:logo.png text/html 2021-01-22T21:17:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://atmos.meteo.uni-koeln.de/ag_crewell/doku.php?id=instruments:tsi:asi&rev=1611350234&do=diff All Sky Imager (ASI) Mentor: J.H. Schween Principle We use an commercially available fish-eye surveillance camera to collect images of the sky and determine cloud amount. The camera is an AXIS M3027-PVE Fixed Dome Network Camera with a common Omnivision CMOS rgb-sensor. Images with a resolution of 800×600 pixels (BMP format) are taken every 20sec. Every pixel above the horizon is investigated for its blue-to-red-ratio and categorized as sky (blue), thin-cloud (light-blue) or cloud (white or … text/html 2023-05-12T09:37:05+00:00 Anonymous (anonymous@undisclosed.example.com) https://atmos.meteo.uni-koeln.de/ag_crewell/doku.php?id=instruments:tsi:current&rev=1683884225&do=diff The YES-TSI that is not here anymore. Goto <https://atmos.meteo.uni-koeln.de/~jschween/tsi/test_axis/> for current images. text/html 2024-07-02T14:38:34+00:00 Anonymous (anonymous@undisclosed.example.com) https://atmos.meteo.uni-koeln.de/ag_crewell/doku.php?id=instruments:tsi:tsi&rev=1719931114&do=diff Total Sky Imager (TSI) (Three channel hemiSpherical Imaging radiometer (TSI)) Mentor: J.H. Schween Principle We use a commercially available fish-eye surveillance camera (AXIS M3027-PVE) to collect images of the sky and determine cloud amount. Images with a resolution of $R$$R_0$$\theta$$ R = R_0 \cdot \sin(\theta/2) $ text/html 2026-01-31T09:45:20+00:00 Anonymous (anonymous@undisclosed.example.com) https://atmos.meteo.uni-koeln.de/ag_crewell/doku.php?id=instruments:tsi:yes-tsi&rev=1769852720&do=diff YES Total Sky Imager (TSI) Mentor: J.H. Schween Principle A Total Sky Imager (TSI) is used to identify cloud types and evaluate cloud coverage. Images from a common electronical webcam are evaluated for the 'blueness' of single pixels. Sky pixels are 'blue', thin clouds appear 'light blue' and thick clouds appear 'white'. The details of the classification are proprietary to the manufacturer.