parallels_xld ( Polygons : Parallels : Len, Dist, Alpha : )
Extract parallel XLD polygons.
parallels_xld examines the XLD polygons passed in
Polygons for parallelism. The resulting parallel
polygons are returned in Parallels. Whether two polygon
segments are parallel depends on their distance (smaller than
Dist), a maximum allowed angle difference
(Alpha, in radians), and a minimum length of the two
polygon segments. Furthermore, the two segments have to overlap.
As a side effect, a quality factor is calculated for each pair of
parallels. It is based on the normalized angular difference and the
normalized length of the overlap area:
PI-delta_alpha 2*overlap
quality = -------------- * --------- with (0 <= quality <= 1)
PI/2 len1+len2
Here, @delta_alpha is the angle difference of the
polygon segments, overlap is the length of the overlap area,
len1 and len2 the length of the polygon
segments, and quality the resulting quality factor.
The quality factor is a measure of parallelism (the larger its
value, the ``more parallel'' the polygons). Finally, the quality
factors of all parallel polygon segments contained in a single
polygon are added, weighted with their length of the overlapping
area.
Parameters
Polygons (input_object)
|
xld_poly-array -> object
|
Input polygons. |
Parallels (output_object)
|
xld_para-array -> object
|
Parallel polygons. |
Len (input_control)
|
number -> real / integer
|
Mimimum length of the individual polygon segments. |
Default value: 10.0 |
Suggested values: 5.0, 10.0, 15.0, 20.0 |
Restriction: Len > 0.0 |
Dist (input_control)
|
number -> real / integer
|
Maximum distance of the polygon segments. |
Default value: 30.0 |
Suggested values: 20.0, 25.0, 30.0, 40.0, 50.0, 75.0 |
Restriction: Dist > 0.0 |
Alpha (input_control)
|
number -> real / integer
|
Maximum angle difference of the polygon segments. |
Default value: 0.15 |
Suggested values: 0.05, 0.10, 0.15, 0.20, 0.30 |
Restriction: (0 <= Alpha) && (Alpha <= (pi / 2)) |
Possible Predecessors
poly_xld
Possible Successors
mod_para_xld,
get_poly_parallel_xld
Copyright © 1996-1997 MVTec Software GmbH