Hi all,<br><br>I plugged in my image data into the itkExpectationMaximizationMixtureModelEstimator using an ImageToListAdaptor. I'm still facing the problem that the estimator stops after the first iteration, even if I use roughly the expected resulting parameters as initial parameters. I built up my application similarly to the example in the software guide (
10.4.4 Expectation Maximization Mixture Model Estimation) : 2 GaussianMixtureModelComponents plugged into the estimator. Has anyone experience with itkExpectationMaximizationMixtureModelEstimator? Why does the algorithm stop?
<br><br>By the way: the KMeans estimator works fine on the data. So I classified my dataset into two subclasses and calculated mean and covariance using MeanCalculator and CovarianceCalculator which worked out fine.<br><br>
Thanx for your help!!<br>Chris<br><br><br><div class="gmail_quote">On Nov 22, 2007 10:31 AM, Christoph Heinzl <<a href="mailto:c.heinzl@gmail.com">c.heinzl@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi<br><br>In my recent application I need to fit gaussian normal distributions<br>into the histograms of my volumetric CT datasets. Usually there are<br>two or three different classes in my data: air regions, material1,<br>
material2. So, first of all I would like to identify the means of my<br>clusters, which is working fine with K-means algorithm. In order to<br>fit now the normal distributions, I some kind of expectation algorithm<br>should work fine. As I saw in the ITK book and from prior postings
<br>there is the itkExpectationMaximizationMixtureModelEstimator which<br>should be able to find both the means of the clusters and the variance<br>of these distributions. But my question is: How should the input data<br>
for this funtion look like? If I input an array containing my<br>histogram data (from bin 0 to 65535) I don't get a valuable result.<br>The algorithm stops at the 1st iteration returning my preset initial<br>values for the clusters. Should the input data be presorted somehow?
<br>Is the raw data of the dataset expected als input or the cumulated<br>histogram information?<br><br>THX in advance,<br>Chris<br></blockquote></div><br>