Re: particle analysis-Feret diameter

Posted by Robert Dougherty on Nov 28, 2005; 4:29pm
URL: http://imagej.273.s1.nabble.com/particle-analysis-Feret-diameter-tp3704371p3704382.html

"Measure ROI Curve" on http://www.optinav.com/ImageJplugins/Measure-Roi.htm
can compute the width of a banana, as well as the Feret diameter.  It uses
an ad-hoc algorithm that works well enough most of the time.

A limitation of Measure ROI Curve has recently been pointed out to me.  If
the banana is so sharply bent that its interior angle is less than about 53
degrees (where 180 degrees would be a straight banana), then the algorithm
can get confused.  This happens because the Feret diameter is not what a
human analyst would regard as the length in this case.  I've been asked to
address the limitation and have not yet found a solution.

Bob

Robert P. Dougherty, Ph.D.
President, OptiNav, Inc.
Phone [phone]
Fax [phone]
www.optinav.com
 

> -----Original Message-----
> From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of
> [hidden email]
> Sent: Monday, November 28, 2005 5:47 AM
> To: [hidden email]
> Subject: Re: particle analysis-Feret diameter
>
> Hello,
> I think that you have only one feret diameter, the maximum.
> draw the convex hull and then compute all the distances between the points
> in
> the hull.
> What is the minimum? The smallest size hole through which the particle can
> pass?
> How about a banana? Does anybody know of an algorithm that can compute the
> smalles feret for an egg and for a banada?
> Juist my monday morning thoughts
> Heberto Ghezzo
> Meakins-Christie Labs
> Montreal - canada