unable to fit Gaussian mixture model

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Niraj 2012-10-17

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Hi, I am trying to recognise the moving objects in binary image. In each frame i have identified the blobs and also have their centroids. I need to fit a GMM so that they gets identified when the blobs overlap each other. could anyone help me in doing this. I tried the gmdistribution.fit function but i am confused with the fact that whether input parameter needs to be the distribution of the coordinates of the blobs in each frame? If this is the case then how will it identify the bob in each frame? Please provide me some help.

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kittu 2012-11-15

编辑：kittu 2012-11-15

在 MATLAB Online 中打开

this could be done something like:

    %
pixelList = [struct.PixelList]; struct is a structure which contains the pixels of interest
obj = gmdistribution.fit(pixelList,k); %k is the number of clusters you want.
sig=obj.Sigma;
mu=obj.mu;
for cluster=1:k
[v,d]=eig(sig(:,:,cluster));
dd=sqrt(d);
ra=2*dd(1,1);
rb=2*dd(2,2);
x0=mu(cluster,1);
y0=mu(cluster,2);
ang = atan(v(2,1)/v(1,1))*(180/pi);
area=pi*ra*rb;
end

you can pass these parameters top draw the ellipse.

Kittu

Niraj 2012-12-7

Thanks kittu, it helped..

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回答（1 个）

Tom Lane 2012-10-18

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I don't know much about analyzing images. But gmdistribution expects its input data to be samples drawn from a Gaussian mixture distribution. If your image is being modeled so that the image values are something like the density of a gmm, then that's more like surface fitting than distribution fitting. Is that the case?