WANTED: Algorithm to fit data points to ellipse

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3 total messages Started by Dave Reimann Thu, 30 Jul 1992 23:56

#146

Author: Dave Reimann
Date: Thu, 30 Jul 1992 23:56

4 lines
600 bytes

I need an algorithm to fit a general ellipse to a set of data points.
By generalized ellipse, I mean one that accounts for any tilt in the
major axis wrt the x-axis.  The data is expected to have some estimation 
error, so I need to handle that.

Re: WANTED: Algorithm to fit data points to ellipse

#157

Author: Dick Rinewalt
Date: Fri, 31 Jul 1992 16:13

18 lines
1292 bytes

In article <1992Jul30.235659.23179@terminator.cc.umich.edu> Dave Reimann,
reimann@terminator.cc.umich.edu writes:
>I need an algorithm to fit a general ellipse to a set of data points.
>By generalized ellipse, I mean one that accounts for any tilt in the
>major axis wrt the x-axis.  The data is expected to have some estimation 
>error, so I need to handle that.

There is an ellipse fitting routine in NIH Image available by anonymous
ftp from alw.nih.gov in the /pub/image directory. Comments in the Pascal
code say that the routine is due to
  Bob Rodieck
  Department of Ophthalmology, RJ-10
  University of Washington
  Seattle, WA, 98195
  (206) 543-2449
The comments also reference
  Cramer, Mathematical Methods of Statistics, Princeton Univ. Press, 945,
page 283

Re: WANTED: Algorithm to fit data points to ellipse

#183

Author: pfennige
Date: Tue, 04 Aug 1992 08:36

15 lines
1285 bytes

In article <1992Jul30.235659.23179@terminator.cc.umich.edu>, reimann@terminator.cc.umich.edu (Dave Reimann) writes:
> I need an algorithm to fit a general ellipse to a set of data points.
> By generalized ellipse, I mean one that accounts for any tilt in the
> major axis wrt the x-axis.  The data is expected to have some estimation 
> error, so I need to handle that.

You can get robust Fortran algorithms least-squares fitting circles or ellipses
(fcircle.f, fellipse.f and ls.f) to 2D data points by anonymous ftp at 
	obs.unige.ch (129.194.64.1) 
in the directory /fit.  The result is invariant by rotation and translation of 
the data points.  fcircle.f and fellipse.f contain both an example program 
and the actual fitting subroutines.  ls.f are linear least-squares subroutines
by Lawson & Hanson. 

	Daniel Pfenniger

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