Multiscale segmentation of satellite data into image objects and knowledge based detection and class

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Multi-scale segmentation of satellite data into
image objects and knowledge based detection and
classification of clouds

• Or
• Teach the computer to analyse what we can see on
  satellite images

Frank-M. Göttsche and Folke-S. Olesen
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What can we see?
AVHRR Ch-2
Where is the compact cloud area of the low
pressure system?
Marked by visual inspection ----
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What can we see?
AVHRR Ch-1
Where is the area of small convective clouds?
Marked by visual inspection ----
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Why can we see more than the computer?
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AVHRR data (5.6.96)
VIS (ch1) 0.63 µm Training-objects marked
NIR (ch2) 0.91 µm
IR (ch 5) 12.0 µm
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Image segmentation
merging of small objects into bigger ones
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Image segmentation
Scale 900
merging of small objects into bigger ones
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Image classification
Training areas forwater, cloud, land
Nearest neighbouron object valuesmean, standard
dev.ch1, ch2, ch5
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Image classification
Scale 30small objects
Classification on small objects average size 23
pixel
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Image classification
Scale 30small objects
Classification of small objects average size 23
pixel
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Object hierachy
Objects of different sizeorganized in layers
Objects and sub-objects
Neighbour objects
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Image segmentation
VIS, scale 4500
VIS, scale 900
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Image object properties
VIS scale 900
VIS mean scale 900
TIR mean scale 900
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Find comma structure
Density Ratio area/radius of object
VIS
Density 4500
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Visual / computer analysis
Find comma structure
Where is the compact cloud area of the low
pressure system?
Found by objective image analysis
Marked by visual inspection ----
VIS
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Small convective clouds
VIS
Number of low clouds
Relative area of low cl.
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Visusal / computer analysis
Where is the area of small convective clouds?
Found by objective image analysis
Marked by visual inspection ----
VIS
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Conclusion applications for clouds
Objective analysis of cloudscurrently only
interactive (manual)

• Frontal zones
• location
• frequency
• movement

Year to year change of circulation patterns
Enhanced WV cycle due to global warming