Introduction
This package was designed to remove simple geometric shapes from pointclouds. E.g. A cube or a sphere. Several of these filters can be applied to a pointcloud in one shot. For more details on the types of filters and their parameters see Filters.
This package includes a full node and a ros interface for one's own node. For more details about the node, like topic names and parameters, see Node.
The package can handle three different input types of pointclouds:
- sensor_msgs/PointCloud2 (this is also the output type)
- sensor_msgs/PointCloud
- sensor_msgs/LaserScan
Additionaly the input data can be throttled to reduce the cpu load.
Node
Input and Output Topics
| Topic Name | Type | Description |
|---|---|---|
| "~/in_cloud" | sensor_msgs/PointCloud2 | Input as new pointcloud type. |
| "~/in_cloud_old" | sensor_msgs/PointCloud | Input as old pointloud type. Will be converted to new pointcloud type. |
| "~/in_laser" | sensor_msgs/LaserScan | Input as single laser scan. Will be converted to new pointcloud type by package "laser_geometry". |
| "~/out_cloud" | sensor_msgs/PointCloud2 | Output of filtering node. |
All topics can be remapped using parameters (see below).
Services
| Service Name | Type | Description |
|---|---|---|
| "~/filter" | pcdfilter_pa/PcdFilterPaCloud | Forced filtering via service call. No throttling is done and input/output cloud is part of service message. |
| "~/add_filters" | pcdfilter_pa/PcdFilterPaFilter | Adding new filters. Old filters are kept. |
| "~/change_filters" | pcdfilter_pa/PcdFilterPaFilter | Adding new filters, but removing all old filters before adding. |
| "~/enable" | std_srvs/Empty | Disables this node. This also disconnects the node from all input messages. |
| "~/disable" | std_srvs/Empty | Enables this node. |
Parameters
Filter
| Parameter Name | Type | Description |
|---|---|---|
| "~/filters" | vector of strings | All pointcloud filters as an array of strings. |
general settings
| Parameter Name | Type | Description |
|---|---|---|
| "~/skip_count" | integer | Input throttling. Number of skipped messages after each processed message. |
| "~/skip_time" | double | Input throttling. Time intervall in seconds. After each processed message, this intervall starts and all input messages will be skipped. |
| "~/tf_lookup_time" | double | Maximum time in seconds for waiting for a specific TF transform. |
| "~/buffer_pointcloud" | bool | Flag for buffering the last received pointcloud. This can be used to test different filters without resending the some pointcloud. |
| "~/debugging" | bool | Flag for enabling extented output. |
| "~/enabled" | bool | Flag for setting start up behaviour. Indicates if node is filtering at startup, or not. |
laser
| Parameter Name | Type | Description |
|---|---|---|
| "~/laser_nan_replacement_value" | double | If a nan-value is represented within the laser scan, it might indicate "no obstacle within range". Therefore this parameters will replace those values with a fixed number. |
topics and services
| Parameter Name | Type | Description |
|---|---|---|
| "~/topic_in_cloud" | string | Name of input topic for new pointclouds. |
| "~/topic_in_cloud_old" | string | Name of input topic for old pointclouds. |
| "~/topic_in_laser" | string | Name of input topic for laser scans. |
| "~/topic_out_cloud" | string | Name of output topic for filtered pointcloud. |
See also this config file. It contains all parameters and their default value.
Filter
Definition
This is the definition of every single filter as a string.
inversion (optional)
| Inversion | Description |
|---|---|
| "" (none) | normal behaviour; points within the volume will be filtered out; all points outside will be kept |
| "!" | reversed behaviour; points within the volume will be kept; all points outside will be filtered out |
type
| Type | Description | Nr Parameters | Nr TF ids |
|---|---|---|---|
| "cube" | specified by its sidelength | 1 parameter | 1 TF |
| "sphere" | specified by its radius | 1 parameter | 1 TF |
| "block" | cuboid specified by its three sidelengths in x,y and z direction | 3 parameters | 1 TF |
| "cylinder" | specified by its radius and its height | 2 parameters | 1 TF |
| "link" | cylinder centered around the two given tfs; specified by its radius and its overshoot | 2 parameters | 2 TF |
| "cone" | cone headed at fist tf and pointing to second tf; specified by its height and its ratio (radius/height) | 2 parameters | 2 TF |
separator
| Seperator | Description |
|---|---|
| ":" | current filter is required; if some tf is missing the whole filtering is aborted and no output pointcloud is generated |
| "?" | current filter may be skipped; if some tf is missing then the current filter is not applied; but in any case the whole filtering and output process is continued |
To control how long the filter should wait for the necessary tf there exists a parameter "~/tf_lookup_time" - see also Node.
dimensions
Number of dimensions depends on the type of the current filter(see above). At least one dimension is always needed, e.g. for a cube. Three dimensions must be set for a cuboid. \ Each dimension is a single number seperated by spaces.
tf
ROS frame id for the filtered objects.
tf_offset (optional)
This allows for an additional offset relative to the given frame id. Order of parameters: x y z qx qy qz qw
Missing parameters will be set to "0". If qw is not set then it will be set to sqrt(1 - qx^2 - qy^2 - qz^2)
tf2 and tf2_offset (optional)
Only valid for type "link" and "cone".
For description see above (tf and tf_offset).
comment
Every character following '#' is ignored. This can be used to give a short comment.
Examples
Filters every point within the following cube - the cube is removed from the pointcloud. \ The sidelength is 3 [meters]. \ The center is aligned with TF frame "base_footprint". \ Corners will be at [+/-1.5 , +/- 1.5, +/- 1.5].
Only points within sphere will stay.
The center of sphere is aligned with TF frame "map".
The radius is 2.3 [meters] and the diameter is 4.6 [meters].
Removes every point within the cuboid.
One corner of the cuboid is at center of TF frame "base_link".
This is due to the additional offset of [0.5, 1 1.5].
Two opposite corners are at [0, 0, 0] and [1, 2, 3].
Removes every point within the cylinder, which is attached to both TF frames. \ The center of the top and bottom surface is exactly at origin of one frame (zero overshoot). \ The radius is 0.2 [meters]. \ The height depends only the relative position of the two frames. \ Also the orientation of the cylinder is not fixed to any frame.
Removes every point outside the cone. \ The top of cone will be at the origin of the TF frame "laser" and the centerline will go straight through the origin of the TF frame "pan_tilt_tilt_link". \ The height is 10 [meters]. \ The angle at the top is 90 degrees (ratio of radius to height is 1:1).
Links and packages
Source code at github
https://github.com/TUC-ProAut/ros_pcdfilter
Related packages
https://github.com/TUC-ProAut/ros_parameter
ROS packages
ros-kinetic-pcdfilter-pa
ROS Build-Status and Documentation
| ROS-Distribution | Build-Status | Documentation |
|---|---|---|
| Indigo | EOL April 2019 | docs.ros.org/indigo |
| Jade | EOL May 2017 | docs.ros.org/jade |
| Kinetic | docs.ros.org/kinetic | |
| Lunar | EOL May 2019 | docs.ros.org/lunar |
| Melodic | upcoming | docs.ros.org/melodic |