Types of errors determined during self-crossings check
№
Type
Description
1
The contour contains double points: the coordinates of points B and C coincide.
The search for double points is performed according to the condition: the distance between the points is less than the threshold for removing identical metric points (usually 0.001 mm).
Correction method: remove the extra point (C).
2
The contour has an overshoot at point B: the value of the angle ABC between two adjacent segments AB and BC is less than the permissible value (d <3 °).
Correction method: remove the extra point (B).
3
Degenerate contour: a non-closed (linear) object has less than 2 points or the contour points have the identical coordinates (double points).
Method of correction: if the contour is the main one — delete the object, otherwise — delete the contour (subobject).
4
Degenerate contour: a closed (linear or areal) object has less than 4 points or the points of the contour have the same coordinates (double points). The segments AB and BA coincide (arrows indicate the direction of the vectors).
Method of correction: if the contour is the main one — delete the object, otherwise — delete the contour (subobject).
5
The contour has self-crossing: segments AB and BC coincide.
Method of correction: remove extra points (B and C).
6
The contour has self-crossing: segments BC, СD and DE coincide.
Method of correction: remove extra points (D and E).
7
The object has a double contour: the pairs of line segments AB and DE, BC and EF, CD and FA coincide. The area of such an object is doubled.
Method of correction: remove extra points (D, E, F).
8
The contour has a self-crossing of the «loop» type: the segments AB and CD intersect.
Method of correction: if the loop has the small area (usually — less than 1 sq.mm) — remove unnecessary points (B and C); otherwise — create a separate object by loop points (B, C and a point of intersection of segments AB and СD), then remove the extra points.
9
The contour has a self-crossing of the «loop» type: contour sections FAB and CDE intersect at point A (D), coordinates of points A and D coincide.
Method of correction: if the loop has a small area (usually — less than 1 sq.mm) — remove unnecessary points (B, C, D); otherwise, create a separate object along the loop points (B, C, D), then delete unnecessary points.
10
The contour has a self-crossing of the «adjacency» type: contour sections FAB and CDE adjoin at point A (D).
Method of correction: if the change of the object's area is acceptable, increase the distance between points A and D (move point A up 0.5 mm); otherwise, apply the loop correction method.
11
The contour has a self-crossing of the «adjacency» type: contour sections HABC and DEFG have a common segment AB (EF).
Method of correction: if the change of the object's area is acceptable, increase the distance between segments AB and EF (move points A and B up 0.5 mm); otherwise, apply the loop correction method.
12
The contour has a self-crossing of the «adjacency» type: the sections of the contour GAB and CDE adjoin at point A (D).
Method of correction: if the change in the object's area is acceptable, increase the distance between points A and D (move point A up 0.5 mm).
13
The contour has a self-crossing of the «adjacency» type: contour sections GABC and DEFG have a common segment AB (EF).
Method of correction: digitize the object along the contour (AGBCD), then delete the original object.
14
The contour has a self-crossing of the «adjacency» type: contour sections GABC and DEFG have a common segment AB (EF).
Method of correction: digitize the object along the outer contour (AGBCD), then delete the original object.
15
The line object has a self-intersection of the «adjacency» type: the last point of the contour F is adjacent to the midpoint of the contour C.
