sample_object_model_3dT_sample_object_model_3dSampleObjectModel3dSampleObjectModel3dsample_object_model_3d (Operator)

Name

sample_object_model_3dT_sample_object_model_3dSampleObjectModel3dSampleObjectModel3dsample_object_model_3d — Sample a 3D object model.

Signature

Description

sample_object_model_3dsample_object_model_3dSampleObjectModel3dSampleObjectModel3dSampleObjectModel3dsample_object_model_3d creates a sampled version of the 3D object model ObjectModel3DObjectModel3DObjectModel3DObjectModel3DobjectModel3Dobject_model_3d which consists of points that have the minimum distance SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance to each other. The created 3D object model is returned in SampledObjectModel3DSampledObjectModel3DSampledObjectModel3DSampledObjectModel3DsampledObjectModel3Dsampled_object_model_3d.

Using sample_object_model_3dsample_object_model_3dSampleObjectModel3dSampleObjectModel3dSampleObjectModel3dsample_object_model_3d is recommended if complex point clouds are to be thinned out for faster postprocessing or if primitives are to be converted to point clouds. Note that if the 3D object model is triangulated and should be simplified by preserving its original geometry as good as possible, simplify_object_model_3dsimplify_object_model_3dSimplifyObjectModel3dSimplifyObjectModel3dSimplifyObjectModel3dsimplify_object_model_3d should be used instead.

If the input object model ObjectModel3DObjectModel3DObjectModel3DObjectModel3DobjectModel3Dobject_model_3d contains only points, several sampling methods are available which can be selected using the parameter MethodMethodMethodMethodmethodmethod:

'fast'"fast""fast""fast""fast""fast":

The default method 'fast'"fast""fast""fast""fast""fast" adds all points from the input model which are not close to any point that was earlier added to the output model. If present, normals, XYZ-mapping and extended point attributes are copied to the output model.

'fast_compute_normals'"fast_compute_normals""fast_compute_normals""fast_compute_normals""fast_compute_normals""fast_compute_normals":

The method 'fast_compute_normals'"fast_compute_normals""fast_compute_normals""fast_compute_normals""fast_compute_normals""fast_compute_normals" selects the same points as the method 'fast'"fast""fast""fast""fast""fast", but additionally calculates the normals for all points that were selected. For this, the input object model must either contain normals, which are copied, or it must contain a XYZ-mapping attribute from which the normals are computed. The z-component of the calculated normal vectors is always positive. The XYZ-mapping is created by xyz_to_object_model_3dxyz_to_object_model_3dXyzToObjectModel3dXyzToObjectModel3dXyzToObjectModel3dxyz_to_object_model_3d.

'accurate'"accurate""accurate""accurate""accurate""accurate":

The method 'accurate'"accurate""accurate""accurate""accurate""accurate" goes through the points of the 3D object model ObjectModel3DObjectModel3DObjectModel3DObjectModel3DobjectModel3Dobject_model_3d and calculates whether any other points are within a sphere with the radius SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance around the examined point. If there are no other points, the original point is stored in SampledObjectModel3DSampledObjectModel3DSampledObjectModel3DSampledObjectModel3DsampledObjectModel3Dsampled_object_model_3d. If there are other points, the center of gravity of these points (including the original point) is stored in SampledObjectModel3DSampledObjectModel3DSampledObjectModel3DSampledObjectModel3DsampledObjectModel3Dsampled_object_model_3d. This procedure is repeated with the remaining points until there are no points left. Extended attributes of the input 3D object model are not copied, but normals and XYZ-mapping are copied. For this method, a noise removal is possible by specifying a value for 'min_num_points'"min_num_points""min_num_points""min_num_points""min_num_points""min_num_points" in GenParamNameGenParamNameGenParamNameGenParamNamegenParamNamegen_param_name and GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value, which removes all interpolated points that had less than the specified number of neighbor points in the original model.

'accurate_use_normals'"accurate_use_normals""accurate_use_normals""accurate_use_normals""accurate_use_normals""accurate_use_normals":

The method 'accurate_use_normals'"accurate_use_normals""accurate_use_normals""accurate_use_normals""accurate_use_normals""accurate_use_normals" requires normals in the input 3D object model and interpolates only points with similar normals. The similarity depends on the angle between the normals. The threshold of the angle can be specified in GenParamNameGenParamNameGenParamNameGenParamNamegenParamNamegen_param_name and GenParamValueGenParamValueGenParamValueGenParamValuegenParamValuegen_param_value with 'max_angle_diff'"max_angle_diff""max_angle_diff""max_angle_diff""max_angle_diff""max_angle_diff". The default value is 180 degrees. Additionally, outliers can be removed as described in the method 'accurate'"accurate""accurate""accurate""accurate""accurate", by setting the generic parameter 'min_num_points'"min_num_points""min_num_points""min_num_points""min_num_points""min_num_points".

'xyz_mapping'"xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping":

The method 'xyz_mapping'"xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping" can only be applied to 3D object models that contain an XYZ-mapping (for example, if it was created using xyz_to_object_model_3dxyz_to_object_model_3dXyzToObjectModel3dXyzToObjectModel3dXyzToObjectModel3dxyz_to_object_model_3d). This mapping stores for each 3D point its original image coordinates. The method 'xyz_mapping'"xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping" subdivides those original images into squares with side length SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance (which is given in pixel) and selects one 3D point per square.

The method behaves similar to applying zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorZoomImageFactorzoom_image_factor onto the original XYZ-images. Note that this method does not use the 3D-coordinates of the points for the point selection, only their 2D image coordinates.

It is important to notice that for this method, the parameter SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance corresponds to a distance in pixels, not to a distance in 3D space as for the other methods.

'xyz_mapping_compute_normals'"xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals":

The method 'xyz_mapping_compute_normals'"xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals""xyz_mapping_compute_normals" selects the same points as the method 'xyz_mapping'"xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping""xyz_mapping", but additionally calculates the normals for all points that were selected. The z-component of the normal vectors is always positive. If the input object model contains normals, those normals are copied to the output. Otherwise, the normals are computed based on the XYZ-mapping.

'furthest_point'"furthest_point""furthest_point""furthest_point""furthest_point""furthest_point":

The method 'furthest_point'"furthest_point""furthest_point""furthest_point""furthest_point""furthest_point" iteratively adds the point of the input object to the output object that is furthest from all points already added to the output model. This usually leads to a reasonably uniform sampling. For this method, the desired number of points in the output model is passed in SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance. If that number exceeds the number of points in the input object, then all points of the input object are returned.

The first point added to the output object is the point that is furthest away from the center of the axis aligned bounding box around the points of the input object.

'furthest_point_compute_normals'"furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals":

The method 'furthest_point_compute_normals'"furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals""furthest_point_compute_normals" selects the same points as the method 'furthest_point'"furthest_point""furthest_point""furthest_point""furthest_point""furthest_point", but additionally calculates the normals for all points that were selected. The number of desired points in the output object is passed in SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance.

To compute the normals, the input object model must either contain normals, which are copied, or it must contain a XYZ-mapping attribute from which the normals are computed. The z-component of the calculated normal vectors is always positive. The XYZ-mapping is created by xyz_to_object_model_3dxyz_to_object_model_3dXyzToObjectModel3dXyzToObjectModel3dXyzToObjectModel3dxyz_to_object_model_3d.

If the input object model contains faces (triangles or polygons) or is a 3D primitive, the surface is sampled with the given distance. In this case, the method specified in MethodMethodMethodMethodmethodmethod is ignored. The directions of the computed normals depend on the face orientation of the model. Usually, the orientation of the faces does not vary within one CAD model, which results in a set of normals that is either pointing inwards or outwards. Note that planes and cylinders must have finite extent. If the input object model contains lines, the lines are sampled with the given distance.

The sampling process approximates surfaces by creating new points in the output object model. Therefore, any extended attributes from the input object model are discarded.

For mixed input object models, the sampling priority is (from top to bottom) faces, lines, primitives and points, i.e., only the objects of the highest priority are sampled.

The parameter SampleDistanceSampleDistanceSampleDistanceSampleDistancesampleDistancesample_distance accepts either one value, which is then used for all 3D object models passed in ObjectModel3DObjectModel3DObjectModel3DObjectModel3DobjectModel3Dobject_model_3d, or one value per input object model. The unit of the sample distance is the usual HALCON-internal unit 'm'"m""m""m""m""m".

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

This operator supports canceling timeouts and interrupts.

Parameters

Example (HDevelop)

gen_box_object_model_3d ([0,0,0,0,0,0,0],3,2,1, ObjectModel3D)
sample_object_model_3d (ObjectModel3D, 'fast', 0.05, [], [], \
                        SampledObjectModel3D)
dev_get_window (WindowHandle)
visualize_object_model_3d (WindowHandle, SampledObjectModel3D, \
                           [], [], [], [], [], [], [], PoseOut)

Result

sample_object_model_3dsample_object_model_3dSampleObjectModel3dSampleObjectModel3dSampleObjectModel3dsample_object_model_3d returns 2 ( H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.

Possible Predecessors

read_object_model_3dread_object_model_3dReadObjectModel3dReadObjectModel3dReadObjectModel3dread_object_model_3d, gen_plane_object_model_3dgen_plane_object_model_3dGenPlaneObjectModel3dGenPlaneObjectModel3dGenPlaneObjectModel3dgen_plane_object_model_3d, gen_sphere_object_model_3dgen_sphere_object_model_3dGenSphereObjectModel3dGenSphereObjectModel3dGenSphereObjectModel3dgen_sphere_object_model_3d, gen_cylinder_object_model_3dgen_cylinder_object_model_3dGenCylinderObjectModel3dGenCylinderObjectModel3dGenCylinderObjectModel3dgen_cylinder_object_model_3d, gen_box_object_model_3dgen_box_object_model_3dGenBoxObjectModel3dGenBoxObjectModel3dGenBoxObjectModel3dgen_box_object_model_3d, gen_sphere_object_model_3d_centergen_sphere_object_model_3d_centerGenSphereObjectModel3dCenterGenSphereObjectModel3dCenterGenSphereObjectModel3dCentergen_sphere_object_model_3d_center, xyz_to_object_model_3dxyz_to_object_model_3dXyzToObjectModel3dXyzToObjectModel3dXyzToObjectModel3dxyz_to_object_model_3d

Possible Successors

get_object_model_3d_paramsget_object_model_3d_paramsGetObjectModel3dParamsGetObjectModel3dParamsGetObjectModel3dParamsget_object_model_3d_params, clear_object_model_3dclear_object_model_3dClearObjectModel3dClearObjectModel3dClearObjectModel3dclear_object_model_3d

Alternatives

simplify_object_model_3dsimplify_object_model_3dSimplifyObjectModel3dSimplifyObjectModel3dSimplifyObjectModel3dsimplify_object_model_3d, smooth_object_model_3dsmooth_object_model_3dSmoothObjectModel3dSmoothObjectModel3dSmoothObjectModel3dsmooth_object_model_3d

Module

3D Metrology