Measure Distance to segmentaion boundary from centroid at arbitrary angles

[Nick Rubert]

Hi listserve,


I'd like to measure the straight line distance from the centroid of a
segmentation to the segmentation boundary for arbitrary angles.  Ideally
this would be a command I could script, so that I could find something like
the maximum distance from the centroid to a segmentation boundary by
iterating over many angles.  ANy ideas would be greatly appreciated.

Thanks,

Nick

[Gabriel Landini]

On Friday 04 Dec 2009  10:17:56 you wrote:
> I'd like to measure the straight line distance from the centroid of a
> segmentation to the segmentation boundary for arbitrary angles.  Ideally
> this would be a command I could script, so that I could find something like
> the maximum distance from the centroid to a segmentation boundary by
> iterating over many angles.  ANy ideas would be greatly appreciated.

Your problem might no have single solution. For very irregular objects, there
might be many boundary points at a given angle.

Here is the principle via ROIs:
Get the ROI of the segmented region
Get the coordinates of the ROI
Get the centroid of the region
For all boundary points:
- Compute the angle between the centroid to that point and your reference
line.  If this is the desired angle (you will have to quantise/bin the value):
- - Use Pythagoras theorem from to compute the distance between the centroid
and the boundary point.

G.

[Gabriel Landini]

On Friday 04 Dec 2009  10:49:41 you wrote:


I meant:
> - - Use Pythagoras theorem to compute the distance between the centroid
> and the boundary point.

G.

[Thomas Boudier]

Hi,

It is implemented in 3D in my 3D library :

http://imagejdocu.tudor.lu/doku.php?id=plugin:morphology:3d_binary_morphological_filters:start

however there is no implementation in plugins yet.

Can you be a bit more specific and give an example image ?

Thomas


Nick Rubert a écrit :

> Hi listserve,
>
>
> I'd like to measure the straight line distance from the centroid of a
> segmentation to the segmentation boundary for arbitrary angles.  Ideally
> this would be a command I could script, so that I could find something like
> the maximum distance from the centroid to a segmentation boundary by
> iterating over many angles.  ANy ideas would be greatly appreciated.
>
> Thanks,
>
> Nick
>
>

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