Posted by
Krs5 on
Aug 10, 2015; 7:47am
URL: http://imagej.273.s1.nabble.com/How-to-analyse-a-pattern-of-holes-tp5013892p5013963.html
Dear Bill,
What is the error message?
Do you mean you want to manually select the pellet holes that you want to include in the circle and exclude the once you don't want? Is this allowed for the analysis?
----I also have a bit of a problem with measuring my ellipse areas. What I do is I draw a line that fits the width of the paper and set the scale. For example, the paper is 507mm wide. After setting the scale, I then draw an ellipse on my shot pattern and use the measure tool. The problem is that I get an area that's way higher than it should be. I've done the measurements by hand originally and worked out the areas and diameters that way, but the results I get in ImageJ are much higher than they should be. Any advice please? Am I doing something wrong? ------
If you have scaled the image and draw an ellipse you can select under Analyze > Set Measurements 'Area' and that should give you the area of your ROI. A quick check using A=πr2 show if/that it is correct. On the image you send I cannot see the edges of the paper. Are you sure the whole 507mm is in the image?
Best wishes
Kees
-----Original Message-----
From: ImageJ Interest Group [mailto:
[hidden email]] On Behalf Of BillyWu
Sent: 07 August 2015 17:49
To:
[hidden email]
Subject: Re: How to analyse a pattern of holes?
Dr. Straatman,
Thank you for getting back to me with the macro. I get an error message when I attempt to use it though, I'm not totally sure why.
Instead of having the software automatically find the pellet holes and draw a circle of best fit, would it be possible to draw a circle of best fit if I pre-defined the pellet holes? The work I am doing is based off of a previous student's work from my university. This is an extract from their thesis that explains what they did, but not how they did it. I need to replicate this in the same way.
/"To obtain a measurement of pellet dispersion the images were analysed using ImageJ software. The pellet holes that comprised the perimeter of dispersion were selected (excluding ‘fliers’; pellets significantly outside the general area of dispersion). The software was then implemented to analyse the selected points and draw a circle of bestfit, with >90% of the total number of pellets included within the circle. The software was then used to provide an area measurement of the circle in mm2, with input of the known dimensions of the paper for scale"/
If you know how I could go about doing what they did then I would very much appreciate help in doing it.
Best regards,
Bill
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