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detect closed shapes formed by several arrays of points

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Ilya
Ilya on 26 Jan 2014
Edited: Ilya on 23 Feb 2014
I plot several arrays containing xy-coordinates of points (using plot(x,y)) and obtain a plot with some curves. The curves form some very distinctive closed shapes (that is, the points describing the curves lie close to each other).
It's needed to "recognize" the closed shapes and to fill them. The coordinates of points forming the shapes and their order are given.
Is it possible without shape recognition tools of the Image Processing Toolbox? If not, then how it can be possibly done with the Image Processing Toolbox?
Any suggestions are welcome!
P.S.: A possible example with 3 closed shapes to detect is given below. The points' coordinates are too lengthy to publish.

  2 Comments

Image Analyst
Image Analyst on 26 Jan 2014
Probably. Here's a suggestion. Attach screenshots or images so we can visualize what you're talking about.

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Accepted Answer

Image Analyst
Image Analyst on 27 Jan 2014
You can do this with the Image Processing Toolbox. There is a function called poly2mask that will give you a binary image that you can then pass in to regionprops to get the centroid.
binaryImage = poly2mask(xVertices, yVertices, rows, columns);
[labeledImage, numberOfRegions] = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Centroid');
allCentroids = [measurements.Centroid];
xCentroids = allCentroids(:,1);
yCentroids = allCentroids(:,2);
But I think poly2mask may combine the 3 regions into one. You'd have to try. You can attach your data via a script or .mat file if you want.

  1 Comment

Ilya
Ilya on 28 Jan 2014
Still it is more desirable to work with numerical coordinates (due to precision and speed considerations). Additional toolboxes are also undesirable, since I don't use the Image Processing Toolbox somewhere else in my project.
However, very much thanks for the suggestion. May be I'll use it in the end.

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