PolyLineEdgeFaults finds edge faults and missing points along the lines of multiple polygons.  

The advanced polygon match fitting ensures that each character is fitted with subpixel precision. With high quality image - translation, rotation, size and skew is optimised before edge fault detection. Below the character M to the left is fitted with translation and rotation - to the right it is fitted with translation , rotation, size and skew. False edgefaults are found on the character only rotated and translated into position. In the example the edge is sampled with a steplength of one pixel.

Setup

Reference - Reference system selection

Global position

• Offset in X - offset x in reference coordinates
• Offset in Y - offset y in reference coordinates

Trace lines

• Count - number of trace lines
• Start point - position of starting point on trace line given in reference coordinates
• End point - position of end point on trace line given in reference coordinates
  • Inverted the sign of start and stop point will change the direction of the trace comb
• Trace step (pixels) - normally 1 - given in pixels
• Line width (pixels) - 0 - trace line is not averaged - a higher value will average N pixels perpendicular to the trace comb

Edge detection

• 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
• Threshold - the threshold or sensitivity of the edge detector - a lower value increases the sensitivity
• Polarity - All transitions | Light to dark | Dark to light
• Mode - Peak | Threshold
• Edge choice - First | Largest | Last

Polygon match - select adjust polygons positions and the polygon is fitted before edge detection

• Repeat count - the number of iteration to fitting the polygons

  • 2 is default but higher values normally increase the accuracy

• Parameters to adjust

  • Translation, rotation - default

  • Translation, scale

  • Translation, scale, rotation and skew

    • Note: good image quality and an increased Repeat Count is needed to get a good fit

    • Note: the shape of the polygon must contain information to be able to calculate all four degrees of freedom

• Keep best points ( % ) - specified the number of edge points used for iteration - a lower value makes it more robust - default is 80%

• Stop if fewer ( % ) - terminates iteration when less than edge points in % is located - default is 50 % and deactivated

Advanced

Missing edgepoint interpolation - Interpolate missing edgepoints

• Max number of points in sequence - the number of points to interpolate

Faults (polygon mismatch) -

• Report faults - 

  • Fault tolerance either given in Pixels or Reference coordinates.

• Min/Max Depth - 

• Min/Max Width - 

• Min/Max Area - 

Gaps (missing edgepoints) - Gaps are defined as number of missing points in sequence.

• Report gaps

• Gap definition

  • Min/Max number of points in sequence

• Treat as missing if distance is longer than given - default off

String result

• Create string result with edgepoint coordinates

• Create string results with polygon match percentages

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

Vector mouse menu - activate by right mouse clicking in the Vector list

• New - creates a new vector

• Delete - deletes the selected vector

• Grid.. - activate dialog for defining polygon grid

• Paste new - paste clipboard as new polygon

• Up - moves polygon up in list

• Down - moved polygon down in list

• Delete all - removes all polygons from list

• Delete empty vectors - remove all empty polygons

Results 

Visualisation