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Release Notes


RadialArcFinder - 35

The tool finds an arc or circle by using a radial trace comb. The trace lines radiates from a center point. On each trace line gradient points are collected. The circle is calculated using all the collected points. It is possible to set radius constraints thus selecting the right circle. 

See Measure Radius for an example of use.

The CircleGauger tool is used when you need to gauge a Circle.


Reference - Reference system selection

Trace lines - the tool's region of interest

  • Center-x - center x of radial trace line
  • Center-y - center y of radial trace line
  • Sector angle - staring angle
  • Sector width - width in degrees
  • Angle step - in degrees - a higher number reduces the number of trace lines
  • Inner radius - given in reference coordinates
  • Outer radius - given in reference coordinates
  • Trace step (pixels) - default 1

Note: A trace line width equal 3 means that each point of the trace line is calculated using the pixel value. It is recommended to increase the traceline width to improve edge detection in low contrast conditions

Point & Click Clipboard Support

The ROI can be managed by the buttons

  • Paste - paste the ROI from the image to the scorpion clipboard
  • Copy - copy the ROI to the image from the scorpion clipboard

Point & Click Clipboard Support

The first point of the line defines the origo of the radial tracecomb. The second point defines the tracecomb. To edit length and width of tracecomb used the tool's fields.

One point will change origo of the radial tracecomb.


Trace line samples dialog - a helper window to set trace line filter parameters and thresholds

  • Middle - show the middle trace line
  • Middle+edges - shows the first, middle and last traceline
  • Selection - show the selected trace lines
  • Line indices - traceline selection
    • example: 2,3,12-15
    • example: 1 3 5 7

  • Show trace line popup - activates a modeless traceline window

Example tracelines - Middle+edges is selected



  • Smooth base - 3 is normally a good value
  • Smooth counter - 1 default - given i pixels
    • The smoothing increasing with higher values
  • Differentiation
    • 0 - give threshold
    • 1 - 1. order differentiation - the derivative - default normally used
    • 2 - 2. order differentiation
  • Mode - Peaks are default. Threshold is only used when Differentiation is set to 0.

Edge Detection

  • Polarity - Dark to light | Light to dark | All transitions
  • Threshold - value lower values means more sensitivity
  • Edge filter - Largest gradient | All points | First point | Last point
    • The filter is used to reduce the number of edge points found
  • Remove points close than - used to reduce to the number of edge points - can speed up execution speed
    • Value is specified in pixels of reference coordinates

Arc Fit

  • Fit tolerance - points outside tolerance is not accepted
    • Tolerance given in pixels or reference coordinates
    • More information - Line fit.
  • Goodness (points) - minimum number of points fitted to circle to be accepted

Arc search parameters

  • Max search count - Number of iterations to find a circle
  • Match Select - Most points | Best match | First match
    • Most points - the most robust circle section criteria
    • Best match - picks the circle with the best fit
    • First match - picks the first circle accepted by Arc Fit criteria

String result

  • Create string result with edge points coordinates - result generated when active



  • Min - minimum radius to accept circle
  • Max - maximum radius to accept circle

Note : Constraints can be active and the constraint can be inverted


  • Min - minimum gradient to accept circle
  • Max - maximum gradient to accept circle

Note : Constraints can be active and the constraint can be inverted



Center (x,y)

Coordinates of the circle’s center point


The circle radius




RMS-value of the line-fit; average deviation (the lower, the better)

Circle coverage




The center of the circle


The found circle

Edge points

The found edge points


Fitted points


Region Of Interest

Trace lines

Trace lines

ExecuteCmd support
- more information executeCmd



Return values


Set Object=ROI;Value=<center/baseline> ok,res Sets the tool's ROI. See Copy/paste ROIs for details.
Get Object=ROI ok,<baseline> Current ROI baseline

Scorpion Vision Version XII : Build 646 - Date: 20170225
Scorpion Vision Software® is a registered trademark of Tordivel AS.
Copyright © 2000 - 2017 Tordivel AS.