segment_object_model_3d — Segment a set of 3D points into sub-sets with similar characteristics.
segment_object_model_3d( : : ObjectModel3D, GenParamName, GenParamValue : ObjectModel3DOut)
The operator segment_object_model_3d segments a set of 3D points
given by a 3D object model with the handle ObjectModel3D into
several sub-sets of neighbored 3D points with similar characteristics like
the same normal orientation or curvature. By default, the operator then
tries to fit a 3D primitive, i.e., a simple 3D shape like a plane,
a sphere, or a cylinder, into each of these sub-sets. As result, the
operator returns a tuple of handles for the 3D object models that
represent the individual sub-sets of 3D points
(ObjectModel3DOut). Within these 3D object models information
is stored that concern, e.g., the success of the fitting and the type
and parameters of the fitted 3D primitive. This information can be queried
from the individual 3D object model with get_object_model_3d_params.
Before calling segment_object_model_3d, the input 3D object model
should be prepared for the segmentation using the operator
prepare_object_model_3d with the parameter Purpose set
to 'segmentation'. If the input 3D object model is not
prepared this way, the operator prepare_object_model_3d is called
internally within segment_object_model_3d to extend the
3D object model with attributes that were not explicitly but only implicitly
contained in the 3D object model.
To control the segmentation and the fitting, you can adjust some
generic parameters within GenParamName and GenParamValue.
But note that for a lot of applications the default
values are sufficient and no adjustment is necessary.
The following values for GenParamName and GenParamValue
are possible:
The parameter specifies the maximum angle between the point normals of two neighbored 3D points (in radians) that is allowed so that the two points belong to the same sub-set of 3D points. For a cylinder or sphere, the parameter value depends on the dimension of the object and on the distance of the neighbored 3D points. I.e., if the cylinder or sphere has a very small radius or if the 3D points are not very dense, the value must be chosen higher. For a plane the value is independent from the dimension of the object and can be set to a small value.
Suggested values: 0.10, 0.15, 0.20
Default value: 0.15
The parameter specifies the maximum difference between the curvatures of the surface at the positions of two neighbored 3D points that is allowed so that the two points belong to the same sub-set of 3D points. The value depends on the noise of the 3D points. I.e., if the noise level of the 3D points is very high, the value must be set to a higher value. Generally, the number of resulting 3D object models decreases for a higher value, because more 3D points are merged to a sub-set of 3D points.
Suggested values: 0.03, 0.04, 0.05
Default value: 0.05
The parameter specifies the minimum number of 3D points needed for a sub-set of connected 3D points to be returned by the segmentation. Thus, for a sub-set with fewer points the points are deleted and no output handle is created.
Suggested values: 1, 10, 100
Default value: 100
The parameter specifies whether after the
segmentation 3D primitives are fitted into the sub-sets of 3D
points. If 'fitting' is set
to 'true', which is the default, the fitting is calculated
and the 3D object models with the resulting handles contain the
parameters of the corresponding 3D primitives. The output parameters
of a cylinder, a sphere, or a plane are described with the operator
fit_primitives_object_model_3d. If 'fitting'
is set to 'false', only a segmentation is performed and
the output 3D object models contain the segmented sub-sets of 3D points.
A later fitting can be performed with the operator
fit_primitives_object_model_3d.
List of values: 'false', 'true'
Default value: 'true'
The parameter determines
if a mapping from the segmented 3D points to image coordinates
is copied to the output 3D object model. This information is
needed, e.g., when using the operator object_model_3d_to_xyz
after the segmentation (e.g., for a visualization). If
'output_xyz_mapping' is set to 'true',
the image coordinate mapping is copied. Note that the parameter is
only valid, if the image coordinate mapping is available in the input
3D object model. Make sure that, if you derive the input 3D object
model by copying it with the operator copy_object_model_3d
from a 3D object model that contains such a mapping, the mapping is
copied, too. Furthermore, the parameter is only valid, if
the 3D points are copied to the output 3D object model, which is set
with the parameter 'output_point_coord'.
If 'output_xyz_mapping' is set to 'false',
the image coordinate mapping is not copied.
List of values: 'true','false'
Default value: 'false'
These parameters are used, if 'fitting' is set
to 'true', which is the default.
The meaning and the use of these parameters
is described with the operator fit_primitives_object_model_3d.
The parameter determines whether the
surface of a triangulated input object model is checked regarding
its conformity to the expected requirements.
If the input 3D object model contains triangles that are topologically
invalid an error message is raised.
If the triangulation was created (triangulate_object_model_3d)
or edited (e.g., by simplify_object_model_3d) by a HALCON
operator, a surface check should not be necessary.
The check can be disabled in order to enhance the runtime by setting
'surface_check' to 'false'.
List of values: 'true','false'
Default value: 'true'
ObjectModel3D (input_control) object_model_3d(-array) → (handle)
Handle of the input 3D object model.
GenParamName (input_control) attribute.name-array → (string)
Names of the generic parameters.
Number of elements: GenParamName == GenParamValue
List of values: 'fitting_algorithm', 'max_curvature_diff', 'max_orientation_diff', 'max_radius', 'min_area', 'min_radius', 'output_point_coord', 'output_xyz_mapping', 'primitive_type', 'surface_check'
GenParamValue (input_control) attribute.name-array → (string / real / integer)
Values of the generic parameters.
Number of elements: GenParamValue == GenParamName
Suggested values: 0.15, 0.05, 100, 'true', 'false', 'cylinder', 'sphere', 'plane', 'all', 'least_squares', 'least_squares_huber', 'least_squares_tukey'
ObjectModel3DOut (output_control) object_model_3d(-array) → (handle)
Handle of the output 3D object model.
segment_object_model_3d returns 2 (
H_MSG_TRUE)
if all parameter values
are correct. If necessary, an exception is raised.
xyz_to_object_model_3d,
read_object_model_3d,
prepare_object_model_3d
get_object_model_3d_params,
object_model_3d_to_xyz,
write_object_model_3d,
clear_object_model_3d
fit_primitives_object_model_3d
3D Metrology