ellipse fitting from a plot in MATLAB

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Sayanta Goswami
Sayanta Goswami 2021-3-25
编辑： Matt J 2021-3-31
I have datapoints in text file which I have imported and ploted. Now I want to do ellipse fitting of that data. Can you please help me with that?

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Image Analyst
Image Analyst 2021-3-25
  6 个评论
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Image Analyst
Image Analyst 2021-3-26
Are you sure you actually tried to adapt my demo? Anyway, it was rather straightforward and you just needed to add a call to fitellipse() at the end of your code. It's attached and produces this plot.
Sayanta Goswami
Sayanta Goswami 2021-3-31
编辑：Sayanta Goswami 2021-3-31
Thanks a lot. I had seen the code but there was some issue with these two files that I have attached herewith.It is not giving Theta value correctly. Theta should come araound zero degree but it is giving 68 degree and 44 degree. Please help me.
I have attached google drive link for the files and the code that I was using.
https://drive.google.com/file/d/1GkB5iX4-N0cfqB5FMG78h7YUU7CIu1LM/view?usp=sharing
https://drive.google.com/file/d/1GkB5iX4-N0cfqB5FMG78h7YUU7CIu1LM/view?usp=sharing

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Matt J
Matt J 2021-3-31
编辑：Matt J 2021-3-31
Theta should come araound zero degree but it is giving 68 degree and 44 degree.
Using ellipticalFit() in,
https://www.mathworks.com/matlabcentral/fileexchange/87584-object-oriented-tools-for-fitting-conics-and-quadrics
[X,Y]=deal( smoothX(jdx:jdx+200000,1),smoothY(idx:idx+200000,1) );
fitobj=ellipticalFit([X,Y].')
[hFit,hData]=plot(fitobj,{'Color','r','LineWidth',3},{'SizeData',2});
xlabel 'X'
ylabel 'Y'
legend([hFit,hData],'Fit','Data')
gives me and angle of about 79 degrees (or 11 degrees to the Y axis). I don't know how close to zero degrees you expected, but the tilt angle in your samples is very visible, so it couldn't be too close.
fitobj =
ellipticalFit with properties:
center: [-0.0156 -0.0130]
a: 0.5679
b: 0.4198
angle: 79.2091

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