Major and Minor axis length
I have been using the scikit-image library for a segmentation task in my master thesis. More specifically I have used the regionprops function for calculation of major and minor axis length of objects. I was wondering why exactly, the eigenvalues are multiplied by 4, before returning the axis length? I realize that you multiply by 2 to get the full length, and I think you multiply by 2 again because of the standard deviation, but I am unsure about this.
Hi Anders, there is different formulations for axis lengths and eccentricity in literature. At the moment, I cannot recall which formulation I used when I implemented the functions. In the end, it does not matter what scaling factor you use, as long as it is consistent. A quick Google search reveals this page: https://books.google.com/books?id=4gBUz_IkkSsC&lpg=PA230&ots=mAAFbCrng_&pg=PA231#v=onepage&q&f=false which seems to confirm my implementation. Following the references, you should be able to figure out more about that. Hope that helps. Best, Johannes On Tue, Jun 16, 2015 at 8:25 AM, Anders Prier Lindvig <aprier90@gmail.com> wrote:
I have been using the scikit-image library for a segmentation task in my master thesis. More specifically I have used the regionprops function for calculation of major and minor axis length of objects. I was wondering why exactly, the eigenvalues are multiplied by 4, before returning the axis length? I realize that you multiply by 2 to get the full length, and I think you multiply by 2 again because of the standard deviation, but I am unsure about this.
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participants (2)
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Anders Prier Lindvig
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Johannes Schönberger