how to find loops in the solar corona vinay kashyap smithsonian astrophysical observatory julia...
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![Page 1: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/1.jpg)
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How to find loops in the solar corona
Vinay KashyapSmithsonian Astrophysical Observatory
Julia Sandell (Columbia) & Thomas Lee (Colorado)
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
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![Page 4: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/4.jpg)
Outline
The Problem: crucial for constraining solar physics parameters
The Real Problem: loops are hard to detect objectively
The Solution: the perfect is the enemy of the good
The Problem with the Solution
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 5: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/5.jpg)
The Problem
The Solar corona is highly structured
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 6: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/6.jpg)
SOLARPHOTOSPHEREVISIBLE5800 K
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SOLARCORONAFe XV 284 A2 MKSOHO/EIT
![Page 8: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/8.jpg)
The Problem
The Solar corona is highly structured
It is dominated by loop like structures thatoverlap each other
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 9: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/9.jpg)
QuickTime™ and aPhoto decompressor
are needed to see this picture.
![Page 10: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/10.jpg)
The Problem
The Solar corona is highly structured
It is dominated by loop like structures thatoverlap each other
The contrast is low, and the structuresare dynamic
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 11: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/11.jpg)
The Practical Problem
A loop detection algorithm does not exist
Loop identification is done by “hunting and pecking”
Analyses are unstable and not reproducible
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 12: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/12.jpg)
The Solution
If you torture them enough, the data will confess.
Morphological processing to extract identifiable features
• enhance contrast• morphologically open loop-like structures
• apply threshold• group contiguous pixels into blobs
• make skeleton• prune skeleton
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
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TRACE image enhance contrast bybackground subtraction
(like unsharp masking)
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enhance contrast bybackground subtraction
open with rotating rectangles
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open with rotating rectangles background subtractedand thresholded
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background subtractedand thresholded
converted to bitmapand percolated into regions
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grouped into regionsand selected
skeleton pruned andoverlaid on data image
![Page 18: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/18.jpg)
pruned skeleton data image
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The Solution
Morphological processing to extract identifiable features
enhance contrastmorphologically open loop-like structures
apply thresholdgroup contiguous pixels into blobs
make skeletonprune skeleton
&estimate error
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
![Page 20: How to find loops in the solar corona Vinay Kashyap Smithsonian Astrophysical Observatory Julia Sandell ( Columbia ) & Thomas Lee ( Colorado ) VLK : JSM](https://reader035.vdocument.in/reader035/viewer/2022081513/56649d3b5503460f94a16358/html5/thumbnails/20.jpg)
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In conclusionBut there are Problems with the Solution
You can only find what you already know exists
Connecting broken loop segments still requiresmanual intervention
Estimating the statistical significance of the detectedfeatures is rudimentary
Not necessarily the optimal heuristic
VLK : JSM 2007 : 411: Image Analysis in Solar Astrophysics
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Comparing with magnetic potential field model
Loop Emergent footpoint
Descendent footpoint
Length
[10 Mm]
Temperature
[K]
A -0.23,0.49 -0.30,0.48 1.4 3.3B 0.32,0.13 0.16,0.13 2.4 4.3C 0.47,0.31 0.63,0.35 1.3 3.1D 0.15,0.15 0.17,0.39 3.8 5.4F 0.40,0.25 0.27,0.24 1.3 3.2G 0.30,0.28 -0.04,0.12 10.8 4.5