Evaluate "Goodness" of elliptical fit

Hi,

When using “fit ellipse” on my objects, I understand that the returned parameters “Major” and “Minor axis” refer to an ellipse that best fit the object.

Is there also a value that describes how well the object fits to an ellipse in the first place, i.e. some R^2 or chi value?

The reason for me asking this is that I am trying to identify bacterial cells which usually have a very nice elliptical shape.

However the images also show many artefacts with objects that are “fuzzy” ore “edgy” and do not fit to an ellipse that well.

Thanks!

Hi,

have you tried using the Extended Particle Analyzer from the BioVoxxel update site? It seems that a parameter like Solidity could be suitable to filter the segmented objects of interest in your case.

Another quite powerful option is the Feature Calculator node in KNIME, offering 2D and 3D geometric features, among many others.

Why don’t you post an example image and what you’ve tried so far?

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Hi,

Solidity is indeed what I was looking for.

See screenshot: a filter on solidity (here: min=0.85, max=1) helps filtering out the “odd shapes”.

Brilliant - Thanks Jan!

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