|
 This
tool finds multiple lines using a traceline. The trace comb can be
rectangular, circular or radial.
LineFinder is a very powerful tool
requiring training and experience to take full advantage of all its
features.
To the right a rectangular tracecomb with 21 lines locates a line. The
fitted points are shown with green circles and the line is visualized in red.
See Locate
detail with two LineFinders for an example of use.
Setup
Reference - Reference system selection
Trace lines - describing the edge search area
The user can select traceline with the following shapes
- Rectangular
- Circular
- Radial
The shape selection is defined by the object.
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 rectangular
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.
 The
circular and radial ROIs are defined by the two points of a line. The first
point defines the origo / center. The second point defines
the center of the tracecomb. To edit the width or length of the trace comb -
use the control fields of the tool.
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 for all
ROI variants
Rectangular trace lines
- Center-x - center x of search comb
- Center-y - center y of search comb
- Angle - angle of search comb
- Length - length of search comb
- Width - width of search comb
- Number of trace lines - Number of trace lines in search comb
- Trace line width - width of each trace line. See
Edges and contours
- Sample step (pixels) - step size between samples. See
Edges and contours
Circular trace lines
- Center-x - center x of search comb
- Center-y - center y of search comb
- Center angle - center angle of circle sector
- Radius mid point - distance from center to middle of search
comb
- Radial length - width of search comb
- Angular width (degrees) - lenght of search comb, an angle
measure
- Number of trace lines - Number of trace lines in search comb
- Sample step (pixels) - step size between samples. See
Edges and contours
Radial trace lines
- Center-x - center x of search comb
- Center-y - center y of search comb
- Center angle - center angle of circle sector
- Radius mid point - distance from center to middle of search
lines
- Radial length - length of search lines
- Angular width (degrees) - width of search comb, an angle
measure
- Number of trace lines - Number of trace lines in search comb
- Sample step (pixels) - step size between samples. See
Edges and contours
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
Advanced
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.
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
- Threshold - value lower values means more sensitivity
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
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
- Inv - will invert the sorting direction
Resulting reference system
- Rotate - the center and angle of the best
line is used as outgoing reference system. Uncheck to ignore the line
angle
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
The following constraints are used to reduce the number of lines reported
as results. Best practice is to use the constraints to add properties of the
inspected objects. This will make the processing go faster and to be more
reliable.
Max number of lines
Active - Enable line number filter
Max - max number of lines to report as a result
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
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
|
BestLine
|
The line deemed first first by the sorting specification |
|
BestLineFat |
The same line, drawn thick |
|
EdgePoints
|
All edge points within the ROI |
|
FittedPoints
|
Edge points fitted to lines |
|
Lines
|
The
lines found by the tool
|
|
LinesFat |
The same lines, drawn thick |
|
ROI
|
Region of interest |
|
Trace
lines
|
Search lines used |
Results
|
Number
of lines
|
The
number of lines found
|
|
Line[n].p.x
|
Line n starting point |
|
Line[n].p.y
|
|
|
Line[n].v.x
|
Line n vector |
|
Line[n].v.y
|
|
|
Center[n].x
|
Center position of line n
|
|
Center[n].y
|
|
|
Length[n]
|
Length ov line n |
|
Angle[n]
|
Line angle, line n |
|
Gradient[n]
|
The average gradient for the fitted tracelines
|
|
Line fit[n]
|
The RMS value of the line-fit for a line
|
|
Trace
line span[n]
|
Number of tracelines between first and last fitted point |
|
Number
of points[n]
|
The number of fitted/accepted points on the line
|
|
Widest
gap[n]
|
The widest gap (no fitted points) on the line |
Note: <n> ranges from 1 to 15
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 |
More examples - Example 33
- Changing the ROI of a tool |
