http://imagej.273.s1.nabble.com/Automatic-location-of-spots-at-intersections-of-arcs-of-spots-Laue-camera-tp3691082p3691086.html
Thanks Michael. The arcs are indeed projections of ellipses. Before
of hyperbola. Alan.
> Hi Alan,
>
> use Process>Binary<Find Maxima to create an image with one point per
> maximum.
> Then Analyze>Tool>Save XY Coordinates to export the list.
>
> Finding the arcs automatically will be much more difficult.
> Assuming that the arcs are ellipses, it would be possible if you write a
> Hough transform that takes advantage of the fact that all all ellipses have
> a vertex at the origin, so there are only 3 parameters for the ellipse
> (angle, a, b). Usually, a Hough transform with 3 parameters should be
> possible (4 parameters would be too much).
> (See the Wikipedia entry for Hough transform).
>
> Hope this helps,
>
> Michael
> ________________________________________________________________
>
> On 17 Sep 2009, at 16:33, Alan Hewat wrote:
>
>> I am interested in the possibility of the automatic measurement of the
>> co-ordinates of isolated spots in an image, and eventually of spots
>> that lie at the intersection of arcs of spots, such as shown by the
>> numbered spots on
http://www.neutronoptics.com/resources/oe-laue.jpg>>
>> This is a back-scattered Laue X-ray diffraction pattern, and is used
>> to determine the orientation of the crystal by solving for the (h,k,l)
>> indices of the diffraction spots; the spots at arc intersections
>> normally have low indices.