| Note: This tutorial assumes that you have completed the previous tutorials: ExtractPolygonalPrismData segmentation. |
ExtractPolygonalPrismData segmentation
Description: ExtractPolygonalPrismData segmentationTutorial Level:
Contents
The following launch file starts a nodelet manager together with a VoxelGrid PCL filter nodelet. The input PointCloud2 topic is set to /scene_pointcloud2.
The default filtering values are set to filter data on the z-axis between 0.01 and 1.5 meters, and downsample the data with a leaf size of 0.01 meters.
The segmentation is performed by first estimating surface normals at each point for a support of 0.015 meters, and then using a RANSAC-based estimator for fitting planes with a threshold of 0.1 meters, and a normal deviation of ~5 degrees (0.09 radians).
The convex hull of the projected planar inliers is estimated and an ExtractPolygonalPrismData nodelet is used to extract all point indices between 0 and 0.5 meters from the planar table support, with their projections falling inside the convex hull.
1 <launch>
2 <node pkg="nodelet" type="nodelet" name="pcl_manager" args="manager" output="screen" />
3
4 <!-- Run a VoxelGrid filter to clean NaNs and downsample the data -->
5 <node pkg="nodelet" type="nodelet" name="voxel_grid" args="load pcl/VoxelGrid pcl_manager" output="screen">
6 <remap from="~input" to="/scene_pointcloud2" />
7 <rosparam>
8 filter_field_name: z
9 filter_limit_min: 0.01
10 filter_limit_max: 1.5
11 filter_limit_negative: False
12 leaf_size: 0.01
13 </rosparam>
14 </node>
15
16 <!-- Estimate point normals -->
17 <node pkg="nodelet" type="nodelet" name="normal_estimation" args="load pcl/NormalEstimation pcl_manager" output="screen">
18 <remap from="~input" to="/voxel_grid/output" />
19 <rosparam>
20 # -[ Mandatory parameters
21 k_search: 0
22 radius_search: 0.015
23 # Set the spatial locator. Possible values are: 0 (ANN), 1 (FLANN), 2 (organized)
24 spatial_locator: 0
25 </rosparam>
26 </node>
27
28 <!-- Segment the table plane -->
29 <node pkg="nodelet" type="nodelet" name="planar_segmentation" args="load pcl/SACSegmentationFromNormals pcl_manager" output="screen">
30 <remap from="~input" to="/voxel_grid/output" />
31 <remap from="~normals" to="/normal_estimation/output" />
32 <rosparam>
33 # -[ Mandatory parameters
34 model_type: 11
35 distance_threshold: 0.1
36 max_iterations: 1000
37 method_type: 0
38 optimize_coefficients: true
39 normal_distance_weight: 0.1
40 eps_angle: 0.09
41 </rosparam>
42 </node>
43
44 <node pkg="nodelet" type="nodelet" name="extract_plane_indices" args="load pcl/ExtractIndices pcl_manager" output="screen">
45 <remap from="~input" to="/voxel_grid/output" />
46 <remap from="~indices" to="/planar_segmentation/inliers" />
47 <rosparam>
48 negative: true
49 </rosparam>
50 </node>
51
52 <!-- Project the planar inliers -->
53 <node pkg="nodelet" type="nodelet" name="project_plane_inliers" args="load pcl/ProjectInliers pcl_manager" output="screen">
54 <remap from="~input" to="/voxel_grid/output" />
55 <remap from="~indices" to="/planar_segmentation/inliers" />
56 <remap from="~model" to="/planar_segmentation/model" />
57 <rosparam>
58 model_type: 11
59 copy_all_data: false
60 copy_all_fields: true
61 </rosparam>
62 </node>
63
64 <!-- Compute the convex hull -->
65 <node pkg="nodelet" type="nodelet" name="convex_hull" args="load pcl/ConvexHull2D pcl_manager" output="screen">
66 <remap from="~input" to="/project_plane_inliers/output" />
67 </node>
68
69 <!-- Extract the object clusters using a polygonal prism -->
70 <node pkg="nodelet" type="nodelet" name="extract_objects_table" args="load pcl/ExtractPolygonalPrismData pcl_manager" output="screen">
71 <remap from="~input" to="/extract_plane_indices/output" />
72 <remap from="~planar_hull" to="/convex_hull/output" />
73 <rosparam>
74 height_min: 0
75 height_max: 0.5
76 </rosparam>
77 </node>
78
79 <node pkg="nodelet" type="nodelet" name="extract_objects_indices" args="load pcl/ExtractIndices pcl_manager" output="screen">
80 <!-- Extract_plane_indices needs to be negated for this work -->
81 <remap from="~input" to="/extract_plane_indices/output" />
82 <remap from="~indices" to="/extract_objects_table/output" />
83 <rosparam>
84 negative: false
85 </rosparam>
86 </node>
87 </launch>