How to calculate the centroid / center of a patch?

Hi, how can I calculate the centroid / center of a patch?

Maybe something like this?

[Xc,Yc] = centroid(patch('XData',X,'YData',Y))

[jessupj]

i have you tried polyshape instead of a patch? you're defining the patch there with x,y data, so you can use those data to define the right object to apply centroid to

[Sim]

Thanks a lot @jessupj ! Indeed, @David Hill showed (I think at the same time with you) this solution :)

Answer 1

[David Hill]

pgon=polyshape(X,Y);
[x,y]=centroid(pgon);

Answer 2

[Constantino Carlos Reyes-Aldasoro]

The data X,Y must have been previously calculated from some raw data, say a thresholded figure, it is from that data you can easily calculate centroids with regionprops

https://uk.mathworks.com/help/images/ref/regionprops.html

[Sim]

Thanks a lot @Constantino Carlos Reyes-Aldasoro, very kind!

(however I accepted the @David Hill solution since showing an example of code)

Answer 3

[Image Analyst]

Depends on what you have. If you have just arbitrary (x,y) data gotten somehow, like through assignment, then you can create a polyshape with the polyshape() function, and then use centroid(), like @David Hill showed.

If you have a binary image (like @Constantino Carlos Reyes-Aldasoro assumed -- say from thresholding), and want the centroid of each region, you can use regionprops():

props = regionprops(binaryImage, 'Centroid');
xyCentroids = vertcat(props.Centroid)

If you'd like a tutorial on image segmentation that shows that, you can see my Image Segmentation Tutorial:

Image Analyst's File Exchange

[Sim]

Yes, very true, it depends on what you have!

Yes, both replies from @David Hill, @Constantino Carlos Reyes-Aldasoro and @jessupj are very good, and it just depends on what data / scenario you have....

Thanks a lot for the Tutorial! Seems very interesting! I guess this one: