Finding matching points between two 2d point sets, but different sizes

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photoon 2021-2-25

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评论： photoon 2021-2-26

I am trying to find the way of identifying matching points between two sets (they are xy coordinates from two shifted images). Their sizes are different. Both sets have many points that are not shared. In other words, I look for algoriths to find same points between two shifted 2D point sets, which are not identical.

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photoon 2021-2-25

I am sorry. Let me attach them again.

There are no logic. I just chose them visually. If you scatter plot them, you will be able to tell easily.

photoon 2021-2-25

If we just use closest distance criteria, that wouldn't work because images from which points are collected are drifted from each other.

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回答（3 个）

weikang zhao 2021-2-25

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在 MATLAB Online 中打开

if you dont need a very precise result,

clear
load('xy1.mat');
load('xy2.mat');
fixdistance=[-0.27,2.3];
newxy1=xy1+fixdistance;
dis=@(x,y) sum((x-y).^2);
result=struct([]);
structcount=1;
for i=1:size(newxy1,1)
    for j=1:size(xy2,1)
        if dis(xy2(j,:),newxy1(i,:))<0.1
            result(structcount).xy1num=i;
            result(structcount).xy2num=j;
            result(structcount).xy1=xy1(i,:);
            result(structcount).xy2=xy2(j,:);
            structcount=structcount+1;
        end
    end
end

the struct result contains the results you need. If you need a more general and more accurate method to deal with a large number of similar problems, you need to design an algorithm to estimate fixdistance.

have fun!

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weikang zhao 2021-2-25

by the way, optical flow may be help to estimate fixdistance

photoon 2021-2-25

How to estimate fixdistance was my question. Thank you for your nice rephasement

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weikang zhao 2021-2-26

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I provide a feasible solution. Assuming that the length of xy1&`xy2` are m and n, first generate a set of size m*n, including the distance between any pair of points, and then deploy a clustering algorithm or GMM fitting algorithm, the cluster center is the fixdistance.

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photoon 2021-2-26

Sorry, what is xy1&`xy2`?

weikang zhao 2021-2-26

The two sets you provided

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KSSV 2021-2-26

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Read about knnsearch.

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photoon 2021-2-26

I read knnsearch. Simply running knnsearch(xy1, xy2) gives a result. However, I don't thinkt this is what I want. Do I have a misunderstanding? Or could we apply this idea for measuring similiarity between two point sets?

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