How do I find the centre of gravity for an irregular shape?

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Sudev Parthiban 2019-7-2

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https://ww2.mathworks.cn/matlabcentral/answers/469852-how-do-i-find-the-centre-of-gravity-for-an-irregular-shape

评论： Sudev Parthiban 2019-7-17

Screenshot (82).png

I have given the marked coordinates and region of interest in which I would like to find the centre of gravity for, please help me.

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Jan 2019-7-2

In which format are the input data given?

Sudev Parthiban 2019-7-15

编辑：Jan 2019-7-15

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It is an ultrasound image it is in .mat format... This is my code:

clc
clear
close all
cd('C:\Users\ADMIN\Desktop\Sudev\Objective 1')
load('ROI1.mat');  %Load data from file  
figure(1); clf;
subplot(1,2,1);
imshow(paveikslas,[])
paveikslas(1:200,1:200,:) = 0;
figure(1); clf;
subplot(1,2,1);
imshow(paveikslas,[])
hold on
plot(x_poly, y_poly,'r','LineWidth',2)
title('Overlap of ROI on Bscan')
subplot(1,2,2);
plot(x_poly); hold on;
plot(y_poly,'-r');
title('Coordinates of ROI')
    figure(2)
plot(x_poly, y_poly,'r','LineWidth',2)
axis equal
title('ROI to be calculated for Center and Axis')

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Answer 1

Bruno Luong 2019-7-15

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https://ww2.mathworks.cn/matlabcentral/answers/469852-how-do-i-find-the-centre-of-gravity-for-an-irregular-shape#answer_383244

在 MATLAB Online 中打开

You can get the coordinates of the centroid if you have a boundary coordinates of a polygonal region:

[xc,yc] = polygoncentroid(x_poly,y_poly)

using this function

function [xc,yc] = polygoncentroid(x,y)
xn = circshift(x,-1);
yn = circshift(y,-1);
A = x.*yn-xn.*y;
a = 3*sum(A);
xc = sum((x+xn).*A)/a;
yc = sum((y+yn).*A)/a;
end

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Sudev Parthiban 2019-7-17

Thank you it worked for me

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Answer 2

Kaustav Bhattacharya 2019-7-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/469852-how-do-i-find-the-centre-of-gravity-for-an-irregular-shape#answer_381681

Refer this link. It might help. https://in.mathworks.com/matlabcentral/answers/339583-hellou-could-i-ask-for-help-finding-the-center-of-gravity-of-the-object

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Sudev Parthiban 2019-7-15

It is in DICOM format.

Jan 2019-7-15

编辑：Jan 2019-7-15

在 MATLAB Online 中打开

The DICOM format is a file format. You have loaded the data from a MAT file. Therefore I think, that "DICOM format" is neither possible, nor does it explain, how the data are represented. All we know currently is that your data are not a binary image. Please provide any explicit details about the input. It would be inefficient if the readers guess, which data you have.

What do you exactly get for:

data = load('ROI1.mat')

Loading data directly into the workspace is prone to bugs. Prefer to catch the data in a variable like in my example.

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