Re: Draw circle around point
Posted by
Michael Schmid on
URL: http://imagej.273.s1.nabble.com/Draw-circle-around-point-tp5011114p5011116.html
Hi anonymous user,
you can draw a circle centered at a point when pressing Command-Shift on a Mac (CTRL-Shift on Linux/Windows).
There is a more elegant way:
Calculate the Euclidian Distance Map (EDM) and just read the value from the status line of the ImageJ panel
http://rsb.info.nih.gov/ij/docs/guide/146-29.html#toc-Subsubsection-29.8.10You need a binary image as an input for the EDM (everything above the surface being black). Have the cursor over the EDM, and use Synchronize Windows to see the position in the original image that corresponds to a given point in the EDM:
http://rsb.info.nih.gov/ij/docs/guide/146-30.html#toc-Subsubsection-30.14.8Michael
________________________________________________________________
On Jan 7, 2015, at 18:34, imagej-user wrote:
> Dear ImageJ Forum,
>
> Despite intensive googleing and searching within this forum, I have not
> found a solution to my problem yet.
> My task is to find find out the shortest distance between a point and an
> irregular surface. I wanted to do this as follows:
> Draw a circle around the point (meaning the point is the middle point of the
> circle) and keep on drawing (hold left mouse button) as long as the circle
> hits the surface somewhere (release left mouse button).
> Then measure the radius of the circle ("Analyze" -> "Measure"). The measured
> distance (radius) should be equal to the shortest distance between that
> point and the surface.
>
> At first, I tried it with the built-in ellipse/circle tool in ImageJ but the
> problem is that ImageJ does not draw the circle from the middle point
> (concentrically) but from the top.
>
> Then, I found the concentric circle macro on the internet. The problem with
> this tool is, that it only draws circles with pre-defined radii. This does
> not work for me, as the radius of the circle is the unkown variable I want
> to measure.
>
> According to my understanding, the best solution would be a cicrle tool
> (like the built-in) which lets you draw a circle from the center.
>
> I hope my problem is understandable. I would appreciate your help very much.
> Thank you!
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