Solidity

[I O Ogunniyi]

Hello Dear:

Please what does the Solidity data measure?
I have particles of porous structure to analyse. I chose 'include hole' in the Analyse Particle dialogue box. In the result, the solidity increased. Implying that the area measured is more solid? Why not return 1? Please, how is the solidity defined?
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[gankaku]

Hi (unknown),

Solidity is the area of your features divided by their convex area (the imaginary convex hull around it). See also the ImageJ manual v1.46r page 137.
Including the holes increases the area since holes are subtracted from the overall area. Thus, the quotient increases because the convex area will stay the same. It is therefore an indicator how "ruffled" the border of your features are or how many (not quantitatively) concave cavities are on the surfaceof your features.

Hope this helps.

please include name in your conversations, that makes it more personal.

Best,
Jan

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[Andrei Stefan]

hi,

I am very interested in this topic and I would like to clarify something
because I am thinking more like a biologist not a mathematician.
An increase value, shows that the shape is more "ruffled" or more "solid"?

Thank you very much!

Best regards,
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Ștefan Andrei Cătălin, DVM, MSc, PhD student


University of Agricultural Science and Veterinary Medicine Cluj-Napoca

Faculty of Veterinary Medicine

Department of Pathophysiology


Romanian Equine Veterinary Association member

A.V.E.R. www.ecvet.ro


Mobile phone: [phone]

Fax: [phone]

E-mail: [hidden email]

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[Gabriel Landini]

On Wednesday 29 May 2013 13:18:28 you wrote:
> I am very interested in this topic and I would like to clarify something
> because I am thinking more like a biologist not a mathematician.
> An increase value, shows that the shape is more "ruffled" or more "solid"?

The definition of solidity I use in the particles4/8 plugins (which I have the
idea also mentioned in Russ' book? not sure...) is:
Solidity = Area/Convex_Area
The convex area is the area inside the convex hull of the 2D object.
So the closer the convex hull approaches the perimeter of the original object,
the closer its value is to 1. There are various ways of defining the concept
of "area" in images, ideally the two areas should be obtained using the same
method for the above to make sense.

Cheers

Gabriel

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[JuliusT2]

Hi everyone,
here's a question regarding the calculation of solidity:
using the Roi methods, i can get the Convex hull as a polygon.
now, how do i calculate the area of this irregular polygon?
Thanks,
J