Rank: 215 based on 336 downloads (last 30 days) and 3 files submitted
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Richard Brown

E-mail
Company/University
University of Canterbury
Lat/Long
-43.5, 172.6

Personal Profile:

Postdoc in the BlueFern High Performance Computing centre at the University of Canterbury. Working on large-scale numerical computation and modelling.

Professional Interests:
numerical analysis, modelling, computer vision, mathematical biology

 

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Files Posted by Richard View all
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(last 30 days) 		Comments Rating
07 Sep 2007 Published MATLAB Files nearestneighbour.m Computes nearest neighbour(s) by Euclidean distance Author: Richard Brown closest, nearest, neighbour, neighbor, delaunay, dsearch 151 5
  • 5.0
5.0 | 3 ratings
29 May 2007 Published MATLAB Files fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown approximation, conic, least squares, interpolation, fit, ellipse 120 18
  • 4.66667
4.7 | 6 ratings
21 May 2007 Published MATLAB Files fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown fitcircle, circle, least squares, approximation, interpolation, gauss newton 65 16
  • 4.6
4.6 | 5 ratings
Comments and Ratings by Richard View all
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04 Mar 2013 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown

@leon, not directly. It fits ellipses to pairs of points that are assumed to represent the ellipse boundary. So, you need to segment your images first, then extract the boundary points and fit the ellipse to those.
07 Sep 2012 fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown

@Tolga, thanks -- and yes, I know. I deliberately wanted to avoid any toolbox dependencies.

I haven't done any comparisons of efficiency -- if you do you could let us know! But accuracy is simply dependent on the tolerance you specify.
28 Jun 2012 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown

@Irfan: x and y values!
21 May 2012 fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown

My previous comment got lost -- the 2 norm residual is the sum of the squared perpendicular distance from each data point to the fitted circle
21 May 2012 fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown

Also, @Graeme, the accuracy of the fitted circle depends on the kinds of errors that are in your data. If you assume there is a true underlying set of parameters that you're trying to find, and that your data is normally distributed, then the accuracy will decrease with number of data points as something like s / sqrt(n), where s is the standard deviation of perpendicular distances to the fitted circle, and n the number of data points. The error will then probably follow some kind of t distribution.

Comments and Ratings on Richard's Files View all
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Updated File Comment by Comments Rating
05 Mar 2013 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown leon

Richard Brown,
how to segment the images?
04 Mar 2013 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown Brown, Richard

@leon, not directly. It fits ellipses to pairs of points that are assumed to represent the ellipse boundary. So, you need to segment your images first, then extract the boundary points and fit the ellipse to those.
27 Feb 2013 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown leon

Richard Brown，

your program can fitting an ellipse to mango image?

http://snag.gy/NbIES.jpg

http://snag.gy/tWFMb.jpg

http://snag.gy/b3X7E.jpg

http://snag.gy/lRlfX.jpg

http://snag.gy/fzAVq.jpg

http://snag.gy/qq5WN.jpg

http://snag.gy/bSjbb.jpg

http://snag.gy/aEvwq.jpg

http://snag.gy/S0VNB.jpg

http://snag.gy/6Q6uA.jpg

http://snag.gy/Ov0br.jpg

http://snag.gy/uRbKw.jpg

Thank you.

08 Oct 2012 fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown Farhand, Sepehr

07 Sep 2012 fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown Brown, Richard

@Tolga, thanks -- and yes, I know. I deliberately wanted to avoid any toolbox dependencies.

I haven't done any comparisons of efficiency -- if you do you could let us know! But accuracy is simply dependent on the tolerance you specify.
Top Tags Applied by Richard
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approximation, interpolation, least squares, circle, closest
Files Tagged by Richard View all
  • 1 - 3 of
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Updated   File Tags Downloads
(last 30 days) 		Comments Rating
07 Sep 2007 Published MATLAB Files nearestneighbour.m Computes nearest neighbour(s) by Euclidean distance Author: Richard Brown closest, nearest, neighbour, neighbor, delaunay, dsearch 151 5
  • 5.0
5.0 | 3 ratings
29 May 2007 Published MATLAB Files fitellipse.m Fit ellipses to 2D points using linear or nonlinear least squares Author: Richard Brown approximation, conic, least squares, interpolation, fit, ellipse 120 18
  • 4.66667
4.7 | 6 ratings
21 May 2007 Published MATLAB Files fitcircle.m Fits circles to 2D data using nonlinear least squares to minimise geometric error Author: Richard Brown fitcircle, circle, least squares, approximation, interpolation, gauss newton 65 16
  • 4.6
4.6 | 5 ratings

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