comp.lang.idl-pvwave archive: archive » Re: Measuring sphericity of a set of voxels.

Home » Public Forums » archive » Re: Measuring sphericity of a set of voxels.

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Measuring sphericity of a set of voxels. [message #67800]

Fri, 28 August 2009 08:46

cgguido
Messages: 195
Registered: August 2005

Senior Member

Thanks for your reply pp!

> Though spherical distributions have 3 equal moments of inertia, it
> also happens for other shapes.

yeah, that is what i meant when I said there would be a better way.

>
> You could calculate the density as a function of spherical
> coordinates, and them see how constant the density is for a given
> radius (or the integrated mass under some radius), as a function of
> the two angles. The first thing I would do is to make a plot of those
> quantities to see how flat the curves are, then start looking for
> measures of it (the standard deviation being the simplest one). It
> seems to me that the tricky part to calculate those things may be
> resolution issues, if the number of points you have is not very large.

Indeed it could be a problem since my blobs are about 3 or 4 pixels in
diameter...

What about calculating the correlation between the blob brightness and
the brightness of an ideal sphere "imaged" with no voxel noise? Could
even do this twice: once for a solid sphere and once for a sphere with
a gaussian distribution of brightness....

What do you think?

Thanks,
Gianguido

Report message to a moderator

[Message index]

		Re: Measuring sphericity of a set of voxels. By: cgguido on Fri, 28 August 2009 08:46
		Re: Measuring sphericity of a set of voxels. By: penteado on Thu, 27 August 2009 22:22

Previous Topic:	display polygon on the image
Next Topic:	Re: Image statistics via moving window

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Oct 11 14:41:11 PDT 2025

Total time taken to generate the page: 0.07674 seconds