How to remove edges from objects in Matlab?

Question

asdf 2019-1-9

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编辑： asdf 2019-1-12

Let's say I have an array of objects `objects` and each object contains `vertices`

So for example, let's say I have 2 `objects`, each containing 4 `vertices`, and I plot the vertices and connect them using a line in Matlab:

size_vertices=size(vertices);
    for o=1:length(objects)
        for v=1:size_vertices(1)-1
            plot([vertices(o, v,1) vertices(o, v+1,1)], [vertices(o,v,2) vertices(o,v+1,2)], '-k' )
        end
    end

So let's say `

vertices(1,:,:)=[1 5; 1 1; 5 1; 4 6]

`

and `

vertices(2,:,:)=[5 10; 3 8; 1 5; 4 6]

how can I remove the inner edges?

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Answer 1

Walter Roberson 2019-1-9

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Provided that your polygons never have crossed lines and are never disconnected, then you can use boundary(), making sure to set the shrink factor high (e.g., 1). boundary() was added in R2014b.

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Walter Roberson 2019-1-9

create a graph object and use conncomp to find the connected components and boundary each group.

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Answer 2

Image Analyst 2019-1-9

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bwboundaries() only works with a digital image, not something plotted in the graphical overlay using plot(). Do you have a digital image? If not, try using boundary() like Walter initially suggested. If you have a digital image, you can use bwboundaries() or bwperim().