New strategies and technologies for the safety of navigation in the Mediterranean
sea
Vassilia Karathanassi, Pol Kolokoussis
[email protected], [email protected]
Laboratory of Remote Sensing National Technical University of Athens
Remote Sensing Surveillance Technologies
SST-234096
21 November 2012 Centro Culturale De Laugier, Portoferraio, Isola d’Elba (ITALY)
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Optical Remote Sensing • Spectroscopy
– Laboratory measurements – In situ measurements
• Hyperspectral remote sensing • Multispectral remote sensing
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Spectroscopy Laboratory measurements
Is it possible to detect the oil type? Yes. Reflectance is rising from light to heavy oils. RWATER < RKEROSENE < RHEATING OIL < RCRUDE OIL < RHEAVY FUEL < RMARINE
FUEL OIL. Ratios between R of each oil type and R of sea water (344.51 nm) OIL TYPE RATIOS DAYS KEROSENE 1.53-1.54 1,2 HEATING OIL 1.64-1.76 1,2 CRUDE OIL 1.86-1.89 1,2,3 SRFO 2.08-2.09 1,2,3 BUNKER 3 2.30-2.51 1,2
Laboratory experiments included 13 oil types
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Is it possible to detect the thickness of the oil?
Yes. The thicker the oil spill, the higher its reflectance.
8 different thicknesses ranging from 1μm to
2mm
Best-fit functions for each oil type
Spectroscopy Laboratory measurements
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Spectroscopy From laboratory to in situ measurements
Does the oil spill present the same spectral signature in the marine environment?
No. Thin oil-spills and sea water present sea bottom contributions.
Denser oils like the Arabian
present minor sea bottom contributions even for thin layers of oil-spills (150μm).
WE NEED AN EXTENDED OIL SPECTRAL LIBRARY IN MARINE ENVIRONMENT
Example of spectral signatures of blend oil-spill in marine environment
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Hyperspectral Remote sensing
In hyperspectral imagery each pixel contains a unique, continuous spectrum which is used for the identification of materials by their reflectance.
Hyperspectral Sensor
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Airborne Hyperspectral images
CASI-550 airborne hyperspectral imagery has been acquired for the ARGOMARINE project
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Hyperspectral Remote sensingOil spill detection
Results of the hyperspectral oil-spill detection methodology for the Laganas bay, Zakynthos. The small and very thin oil spill was caused by a natural oil outflow.
Can we detect oil spills by processing a hyperspectral image? - Yes. Even very thin oil-spills can be detected. The only constraint is the presence of clouds. They should be excluded from the image. Do airborne and in situ spectral measurements coincide? - Almost Yes.
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Hyperspectral Remote sensingMethodology for oil spill detection
Can we detect the type of an oil spill by processing a hyperspectral imagery? Yes. If there is an extended Spectral Library for the marine environment under real biophysical conditions.
Pre-processing of the hyperspectral image (radiometric, atmospheric correction and georeference)
Signal subspace estimation (The Intra-StD method has been developed within ARGOMARINE)
Dimensionality reduction
Endmember extraction (The Improved-SEE method has been
developed within ARGOMARINE)
SAM classification or Abundance fraction algorithm for thickness estimation (The NBM method has been developed within
ARGOMARINE)
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Hyperspectral Remote sensingOil spill thickness estimation
Map of oil-spill relative thickness
Can we estimate the thickness of an oil spill by processing a hyperspectral imagery? Yes. Relative thickness for the oil-spill can be estimated. This could lead to absolute thickness estimation in case that in situ measurements in the area with the greatest oil concentration is performed. Can we avoid in situ measurements? Yes. If there is an extended Spectral Library for the marine environment under real biophysical conditions.
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Hyperspectral Remote SensingHow to build an extended Spectral
Library for the marine environment
Is it tested? Only on MODIS and ASTER imagery with Satisfactory results. A next research program is needed.
The Integrated ARGOMARINE methodology
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Multispectral Remote sensingfor oil spill detection
Can we detect an oil spill by processing a very high spatial resolution multispectral imagery?
Yes.
Can we detect the oil spill type?
No.
Can we detect the oil spill thickness?
No.
Is the methodology also applicable on high resolution multispectral images (i.e. Landsat TM)?
Yes (providing average to good detection results).
Object based oil-spill detection on an IKONOS image of Beirut, Lebanon (August
5th 2006)
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Multispectral Remote sensingMethodology for oil spill detection
Multispectral image geocoding.
Application of ATCOR3 atmospheric corrections and conversion of the
raw image digital numbers to surface reflectance values.
Masking of the non-sea areas, i.e. land and clouds.
Image multiresolution segmentation in two
levels (fine and broad).
Oil-spill detection using object based classification
rules
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Remote Sensing potentials for Natural oil outflow detection
Multitemporal color composite of three RapidEye images of Zakynthos: July 13th 2009 (Blue), July 15th 2009 (Green), and July 16th 2011 (Red). The unusual oil-spill occurrences near Zakynthos start from a specific point at the open sea, 6 km south of the area of Keri.
Can we detect an unknown oil natural outflow using remote sensing imagery? Yes. Within the ARGOMARINE project by processing very high resolution (RapidEye) as well as historical high resolution (Landsat TM) multispectral imagery, a large unknown systematic natural oil outflow near the island of Zakynthos has been discovered. The oil-spill occurrence seems to be systematic over a long period of time (it appears on many Landsat images from 1986 till 2012) and was verified by spot test from a NMPZ boat.
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Thank you for your attention
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