Curve Fitting and shape analysis-HELP!

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2 total messages Started by cressrw Mon, 03 Aug 1992 04:23

#85

Author: cressrw
Date: Mon, 03 Aug 1992 04:23

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I have an experiment from which I am trying to extract information by way of 
digitized video and I am having trouble finding routines to do what I want 
to do, almost certainly because I don't know where to look and so I was hoping 
somebody may be able to help me. I have an image of the leading edge of a flow
which is made up of a superposition of eddies, i.e. circles, of varying radii.
What I want to extract is a kind of spectrum of eddy sizes so that I can study
how these develop as the flow progresses. Firstly I need to retrieve the 
underlying curves from the digitized data - surely this must be a trivial form
of curve fitting where it is known that the real curve lies within half a pixel
separation of the digitized 'curve' - all I can find are routines for 
interpolation of data from regular grids, such as a regular array of
measurement points, which is not what I want at all. Then I need to process
the smoothed (piecewise) curves to extract the range of scales and get a kind
of probability density function for sizes. I have a few ideas on how to
accomplish this latter part, but any suggestions would be extremely helpful.
Thanks in advance,
                  Ron Cresswell

Dr R W Cresswell
Centre for Dynamical Meteorology
Monash University
Melbourne
Australia
cressrw@vaxc.cc.monash.edu.au

Re: Curve Fitting and shape analysis-HELP!

#92

Author: Herman Woltring
Date: Mon, 03 Aug 1992 22:37

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In article <1992Aug3.142328.89646@vaxc.cc.monash.edu.au> cressrw@vaxc.cc.monash.edu.au writes:
>
>I have an experiment from which I am trying to extract information by way of 
>digitized video and I am having trouble finding routines to do what I want 
>to do, almost certainly because I don't know where to look and so I was hoping 
>somebody may be able to help me. I have an image of the leading edge of a flow
>which is made up of a superposition of eddies, i.e. circles, of varying radii.
>What I want to extract is a kind of spectrum of eddy sizes so that I can study
>how these develop as the flow progresses. Firstly I need to retrieve the 
>underlying curves from the digitized data - surely this must be a trivial form
>of curve fitting where it is known that the real curve lies within half a pixel
>separation of the digitized 'curve' - all I can find are routines for 
>interpolation of data from regular grids, such as a regular array of
>measurement points, which is not what I want at all. Then I need to process
>the smoothed (piecewise) curves to extract the range of scales and get a kind
>of probability density function for sizes. I have a few ideas on how to
>accomplish this latter part, but any suggestions would be extremely helpful.
>Thanks in advance,
>                  Ron Cresswell
>
>Dr R W Cresswell
>Centre for Dynamical Meteorology
>Monash University
>Melbourne
>Australia
>cressrw@vaxc.cc.monash.edu.au
>  
>

You might try some of the work from Grace Wahba's group at the
University of Wisconsin at Madison, WI/USA as published in the gcv
sublibrary of netlib@research.att.com and its fellow-servers.

Just send an ``send index for gcv'' to the above address for details.
 
Herman J. Woltring, Eindhoven/NL
(Please reply to woltring@nici.kun.nl, not to the bbs address) 
--
   The opinions expressed are not necessarily those of the University of
     North Carolina at Chapel Hill, the Campus Office for Information
        Technology, or the Experimental Bulletin Board Service.
           internet:  bbs.oit.unc.edu or 152.2.22.80

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