read_polygon_xld_dxf — Read XLD polygons from a DXF file.
read_polygon_xld_dxf( : Polygons : FileName, GenParamName, GenParamValue : DxfStatus)
read_polygon_xld_dxf reads the contents of the DXF file
FileName (DXF version AC1009, AutoCAD Release 12) and
converts them to the XLD polygons Polygons.
If no absolute path is given in FileName the DXF file
is searched in the current directory of the HALCON process.
The output parameter DxfStatus contains information about
the number of polygons that were read and, if necessary,
warnings that parts of the DXF file could not be interpreted.
The operator read_polygon_xld_dxf supports the following
DXF entities:
POLYLINE
2D curves made up of line segments
Closed 2D curves made up of line segments
LWPOLYLINE
LINE
POINT
CIRCLE
ARC
ELLIPSE
SPLINE
BLOCK
INSERT
The x and y coordinates of the DXF entities are stored in the column
and row coordinates, respectively, of the XLD polygons
Polygons. The z coordinates of the DXF entities are
ignored.
DXF entities of the type CIRCLE, ARC, ELLIPSE, and SPLINE
are approximated by XLD polygons. The accuracy of this
approximation can be controlled with the two generic parameters
'min_num_points' and 'max_approx_error'
(for SPLINE only 'max_approx_error').
Generic parameters are set by specifying the parameter name(s) in
GenParamName and the corresponding value(s) in
GenParamValue.
The parameter 'min_num_points' defines the minimum
number of sampling points that are used for the approximation.
Note that the parameter 'min_num_points' always refers to
the full circle or ellipse, respectively, even for ARCs or elliptical
arcs, i.e., if 'min_num_points' is set to 50
and a DXF entity of the type ARC is read that represents a semi-circle,
this semi-circle is approximated by at least 25 sampling points.
The parameter 'max_approx_error' defines the maximum
deviation of the XLD polygon from the ideal
circle or ellipse, respectively (unit: pixel).
For the determination of the accuracy of the approximation
both criteria are evaluated. Then, the criterion that leads
to the more accurate approximation is used.
Internally, the following default values are used for the generic parameters:
'min_num_points' = 20
'max_approx_error' = 0.25
To achieve a more accurate approximation, either the value for 'min_num_points' must be increased or the value for 'max_approx_error' must be decreased.
Note that reading a DXF file with read_polygon_xld_dxf results
in exactly the same geometric information as reading the file with
read_contour_xld_dxf. However, the resulting data structure is
different.
Polygons (output_object) xld_poly(-array) → object
Read XLD polygons.
FileName (input_control) filename.read → (string)
Name of the DXF file.
File extension:
.dxf
GenParamName (input_control) attribute.name(-array) → (string)
Names of the generic parameters that can be adjusted for the DXF input.
Default: []
List of values: 'max_approx_error', 'min_num_points'
GenParamValue (input_control) attribute.value(-array) → (real / integer / string)
Values of the generic parameters that can be adjusted for the DXF input.
Default: []
Suggested values: 0.1, 0.25, 0.5, 1, 2, 5, 10, 20
DxfStatus (output_control) string(-array) → (string)
Status information.
If the parameters are correct and the file could be read the
operator read_polygon_xld_dxf returns the value 2 (
H_MSG_TRUE)
.
Otherwise, an exception is raised.
write_polygon_xld_dxf,
read_contour_xld_dxf
Foundation