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The plugin has two separate algorithms available:
'''Full Hough Transform'''
This algorithm performs a full Hough circle transform on every frame. The algorithm then searches for the highest scoring circle first, then the second highest, and so on. When a circle is found, the Hough transform space is cleared out around the found circle to prevent the same circle from being found repeatedly. This parameter can be adjusted to allow for increasing degrees of overlap between neighboring circles.
'''Local Hough Transform'''
This algorithm is designed for high-speed tracking of circles in a time-lapse series. The algorithm performs the full Hough circle transform on the first frame to find the initial radius and position of each circle. In subsequent frames, the algorithm then only performs a Hough transform near the centroid of each circle in subsequent frames. If the number of found circles drops below the minimum number of specified circles, the algorithm performs a full Hough circle transform on the next frame to try and find any circles missed in the local search.
====''Hough score threshold''====
This option sets the minimum cutoff for the Hough score (i.e.
number of votes) that a circle can have to count as a valid object. The search starts with the highest scoring circle, and then the second highest, and so on, so if there are a greater number of circles with a score above the threshold than the limit set in "Maximum number of circles to be found", only the highest scoring circles will be returned. NOTE: When the transform resolution is changed ( see below) the scores will change to. This is because the resolution sets the number of rounds of voting. Therefore, as the number of voting rounds increases, the score per object will increase as well.
====''Hough transform resolution''====