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the "A byte that is 1 if the contour is above its surroundings, and is 0 if the contour is below." explanation does not make sense to me at all. :-(

the context of what i am trying to program is that i am plotting kelvin-helmholtz vortices and i want to highlight only closed contours that break way from the initial vortex. so, contours closed along the outside of my plot are no good. the code i am revising considers all high_low = 1 values as contours that do not fit what we want, but i do not understand why.

any help would be wonderful! thank you!

Jim Lewis
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meganparsec
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1 Answers1

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I am not entirely sure that I am understanding your question properly, but I'll take a shot. For an individual contour, it should have high_low = 0 unless it is at the center of a local maximum. That is, the contours leading up to the center will all have high_low = 0, since they will be in between contours of higher and lower value, and the very centralmost contour will have high_low = 1, since the only contour it is adjacent to is at a lower value. Other local maxima in your field will also have high_low = 1, since it will have a value greater than its surroundings. So if a contour is closed and has high_low = 1, it should represent a separate vortex apart from the initial one.

jdmcbr
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  • thank you for responding! =] ok, i'm still thinking about what you've said, but i have a question in the mean time: does the high_low value help in determining if the closed contour is closed because part of the contour is the actual edge of the plotting window? – meganparsec Aug 17 '11 at 19:27
  • here is a picture of what i'm looking at: http://i.imgur.com/jnDmW.jpg the contour that i want is the thick white one in the upper box. – meganparsec Aug 17 '11 at 19:27
  • My understanding is that high_low value is meaningless for contours that are on the edge of the plotting window. I think you can only trust contours as maxima that have the flag for being closed and have high_low = 1. – jdmcbr Aug 18 '11 at 01:52