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Release Notes
 

  

 
SingleLineFinder - 128

The SingleLineFinder - SLF - tool is a tool used to find single lines.

A second pass is made with tracelines normal the lines can improve lineprecision in sub-pixel resolution systems.

The SLF has a edgepoint mode where no line is calculated.

  • In this mode it can be used to convert laserlines into 3D images or point cloud.
  • In Stereo Vision systems Locate3D can combine and sort the edgepoints to real 3D coordinates

Setup

Reference - Reference system selection

Trace lines - describing the edge search area 

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 ROI can be defined by four points. The two first points define the length and direction of the trace comb. The other points define the width of the trace comb. With the rectangular ROI a line will define the center trace line - thus the length and the direction of the trace comb. One point will change the center point.

  • Two-pass line fit - add a second pass to fit the line, adjusting the search lines to be approximately perpendicular to the line. This improves the line fit accuracy.
  • Center-x - center x of search comb
  • Center-y - center y of search comb
  • Width - width of search comb
  • Length - length of search comb
  • Angle - angle of search comb
  • Count - number of trace lines
  • Distance - distance betwees trace lines
  • Width - width of each trace line. See Edges and contours
  • Step (pixels) - step size between samples.  See Edges and contours

Filter

  • 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. An additional choice is Curve correlation - see below.

More information - see Filter parameters

Note : Combining 2. order differentiation and polarity are used to find the center position of light or dark stripes

Edge Detection

  • Polarity - Dark to light | Light to dark | All transitions
  • Percent threshold - dynamic threshold based on values from current traceline
  • Threshold - (if not percent) value lower values means more sensitivity
  • Min threshold - (if percent) minimum percent value used

Correlation search

To search for a known intensity curve rather than an edge, the correlation search may be helpful. You can select a step or a pulse curve form, or edit your own shape.

  • Step - a step. You can modify leading and trailing edges, and the slope length
  • Pulse - a pulse. You can modify leading and trailing edges, the slope length and the pulse width
  • Custom - create your own shape in the editor described below
  • Minimum Std for match - minimum Std (or variation) in image for a match to be considered
  • Use normalized correlation - normalise by removing mean and equalising Std in both image and curve

Shape editor

The curve shape is edited as a sequence of samples (space delimited). The defined center is where the edge point will be reported in the search.


Advanced

Line fit

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

Fit string results

  • Create string with fitted points polygon - create a polygon of fitted points for external processing
  • Create string with fitted point distances from line- create a polygon of fit distances for external processing
    • Interpolate/extrapolate missing points - estimate values if some points are missing in the fit process

Search parameters

  • Search risk (PPM) - 1 default - a lower value will perform more iterations
  • Max search time (sec) - limits the search in second - default 10

Results

  • Sort results by - Gradient | Fitted Points | Line Lengths | Line Centers | Distance | Separation
  • Inv - will invert the sorting direction

Status

  • Tool fails if no line is found - means that tool returns status = 3

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

  • Middle - show the middle traceline
  • Middle+edges - shows the first, middle and last traceline
  • Selection - show the selected tracelines
  • 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


Constraints

Edge points to keep from each search line - One can filter on position and / or gradient

Position - All | First | Last

No - Number of points to keep pr line

Gradient - All | Largest | Smallest

No - Number of points to keep pr line

Note : The filters are very powerful - one can easily pick the first line by selecting Position = First and limit No to 1 or 2

Line Length 

Active - Enable the filter to remove lines not meeting the length criteria

Min - minimum accepted length in reference coordinates

Max - maximum accepted length in reference coordinates

Gradient 

Active - Enable the filter to remove lines not meeting the gradient criteria

Min - minimum accepted gradient  in reference coordinates

Max - maximum accepted gradient in reference coordinates

Absolute value - check to ignore edge slope direction

Coarse line angle filter - use to reduce processing time - accuracy it not very good - set value with margins 

Active - Enable the filter to remove lines not meeting the angle criteria

Min - minimum accepted angle

Max - maximum accepted angle

Line angle  - with good accuracy 

Active - Enable the filter to remove lines not meeting the angle criteria

Min - minimum accepted angle

Max - maximum accepted angle

Max Gap - missing points on a line to reject a line

Max - number of missing points accepted

Visualisation

EdgePoints All edge points within the ROI
FittedPoints Edge points fitted to the line
Line The line deemed first first by the sorting specification
LineCenter Center position of line
OrigEdgePoints First pass edge points within the ROI
OrigFittedPoints First pass edge points fitted to the line
OrigLine First pass line found by the tool
OrigLineCenter First pass center position on line
OrigROI First pass region of interest
OrigTraceLines First pass search lines used
ROI Region of interest
Trace lines Search lines used


Results

Line.p.x Line starting point
Line.p.y  
Line.v.x Line vector
Line.v.y  
Line.q.x Line end point
Line.q.x  
Line.Length Line length
Line.Angle Line angle
Center.x Center position of line
Center.y  
Length Length ov line (again)
Angle Line angle, line (again)
Line angle Directed line angle
Gradient The average gradient for the fitted tracelines
Line fit The RMS value of the line-fit for the line 
Trace line span Number of tracelines between first and last fitted point
Number of points The number of fitted/accepted points on the line 
Widest gap The widest gap (no fitted points) on the line
Tracelines Number of tracelines used


ExecuteCmd support - more information executeCmd

Command

Parameters

Return values

Comments

Set Object=ROI;Value=<point/line/polygon> ok,res Sets the tool's ROI. See Copy/paste ROIs for details.
Get Object=ROI ok,<line/polygon> Current ROI as rectangular, closed polygon

See also - Example 33 Changing the ROI of a tool


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