Utilities for working with poinclouds

box_filter

Apply a cropbox to a pointcloud. Similar to CropBoxImproved, but less powerful.

Topics:

• in: Incoming pointcloud.
• out: The filtered pointcloud.

Parameters:

• box_frame: Frame to which the pointcloud should be transformed before applying the cropping.
• target_frame: Frame to which the cropped pointcloud should be transformed.
• fields: Pointcloud fields which should be considered for cropping and transformation.
• min, max: 3-tuples describing the cropping box in box_frame coordinates.
• tf_timeout: Timeout for all lookuptransforms. If a transform is not found in this time, the cloud is dropped.
• max_age: Maximum age of the point cloud. If an older cloud arrives, it is dropped.

cloud_proc

Python implementation of a cloud filter chain.

Topics:

• in: Incoming pointcloud.
• out: The filtered pointcloud.

Parameters:

• out_queue_size: Queue size for outgoing clouds.
• in_queue_size: Queue size for incoming clouds.
• in_buff_size: Buffer size for incoming clouds.
• overwrite_in_frame: If nonempty, the frame of incoming clouds will be set to this value.
• filters: List of filters to initialize. Example config:

- cloud_proc.DiscardOld:
    max_age: 10.0
- cloud_proc.Box:
    keep: 1
    lower: [-6.0, -6.0, -1.5]
    upper: [ 6.0,  6.0,  1.0]
    fields: ["x", "y", "z"]
    frame: "base_link"
    timeout: 1.0

Filters:

• Transform: Transform cloud to another frame. Parameters:
  • target_frame: The frame to transform to.
  • fields: List of fields to which the 6-DOF transform should be applied.
  • rotate: List of fields to which only the rotation part of the transform should be applied (e.g. normals).
  • timeout: TF can_transform timeout
  • update_frame: Whether to update frame_id of the resulting cloud.
• Box: Apply box filter to the cloud. Parameters:
  • keep: If True, points inside the box will be kept, otherwise points outside will be kept.
  • lower, upper: Corners of the cropping box.
  • fields, frame, timeout: If frame is set, a Transform filter will be pre-applied with these arguments.
• KeepFields: Keep only the given fields. Parameters:
  • fields: The list of fields to keep.
• DiscardOld: Discard pointclouds older than the given max age.
  • max_age: The maximum allowed age of incoming pointclouds.

odom_cloud_transformer

Transforms point clouds by transforms published as odometry.

Topics:

• input: Incoming pointcloud.
• odom: The incoming odometry topic (matched to pointclouds using time synchronizers).
• output: The filtered pointcloud.

Parameters:

• check_frames: Make sure that the frames in the pointcloud and odometry message match.
• queue_size: Time synchronizer queue size.
• slop: Allowed difference between odometry and pointcloud time. If zero, exact match is required.
• fields: List of fields to which the 6-DOF transform should be applied.
• rotate: List of fields to which only the rotation part of the transform should be applied (e.g. normals).

Improved PCL-based filters CropBoxImproved and PassThroughImproved

This is a bunch of C++ nodelets that extend the functionality of nodelets from pcl_ros.

ImprovedFilter - common base class

This is the common base class for all the improved filters. In addition to the pcl_ros filters, they allow for periodic publishing of the received pointclouds on frequencies different from the input pointcloud. They also provide very detailed diagnostics about the received/published pointclouds.

The transformation procedures also take good care about non-default pointcloud fields like normals (normal_x, normal_y, normal_z) and viewpoints (vp_x, vp_y, vp_z). Normals are only rotated, viewpoints are fully transformed

Topics:

• input: Incoming pointcloud.
• indices: If used, only the selected indices will be taken into account from the incoming pointcloud.
• output: The filtered pointcloud.
• diagnostics: For publishing the diagnostics output.

Parameters:

• From nodelet_topic_tools::NodeletLazy:
  • use_multithread_callback: If true, use the MT nodehandle.
  • lazy: If true, use lazy subscription to input topics (only if output has subscribers).
  • verbose_connection: If true, print verbose info about (dis)connections.
  • duration_to_warn_no_connection: How long to wait before warning that there is no subscriber on output.
• From pcl_ros::PCLNodelet:
  • max_queue_size: Queue size for both incoming and outgoing pointclouds.
  • use_indices: Whether to use indices published on indices topic or use whole pointclouds.
  • latched_indices: Whether to subscribe to indices as a latched topic.
  • approximate_sync: If listening for indices, synchronize them with pointclouds approximately (otherwise exact match is required).
• From pcl_ros::Filter:
  • input_frame: If nonempty, the pointcloud will be transformed to this frame prior to any other actions on it.
  • output_frame: If nonempty, the pointcloud will be transformed to this frame just before publishing.
  • keep_organized: If true, organized pointclouds will be output as organized again (filtered values will be set to NaN).
• Improved filter - periodic publishing:
  • publish_periodically: If true, the filter will publish pointclouds transformed at the current time on rate publish/rate/desired. When a cloud comes in, it is converted to input_frame and stored. When the publication timer triggers, the stored cloud is converted to input_frame at current time using the given fixed_frame. Then the filter is applied, the pointcloud is converted to the output_frame and published.
  • fixed_frame: Only needed when publish_periodically is true. See the description above.
• Improved filter - general:
  • tf_wait_timeout: Timeout for TF canTransform calls.
  • produce_diagnostics: Whether to compute and publish diagnostics of the publisher and subscriber.
  • disable_orig_tf_listener: If true and a shared TF2 buffer has been set to the nodelet before the onInit() call, the original TF listener from pcl_ros::PCLNodelet is disabled (by redirecting its tf topics to nonexistent topics). To launch the nodelet with a shared TF2 buffer, load it into cras_cpp_common/nodelet_manager_sharing_tf_buffer and not a normal nodelet manager. The shared buffer is accessible using the getBuffer() method.
• Improved filter - transform arbitrary channels:
  • remove_other_channels: If True, channels not mentioned in the following parameters are removed from the output.
  • transform_channels_point: List of prefixes of channels to be transformed as points (6DOF). If channel consists of vp_x, vp_y and vp_z, pass only vp_ as the parameter here.
  • transform_channels_direction: List of prefixes of channels to be transformed as vectors or directions (only rotation). If channel consists of normal_x, normal_y and normal_z, pass only normal_ as the parameter here.
  • transform_channels_scalar: List of channels that should not be transformed. This only makes sense to fill when remove_other_channels is True (it says these channels will be retained).
• Improved filter - diagnostics:
  • There are two identical sets of settings, one for the subscriber (input pointclouds, param namespace receive/), and one for the publisher (output pointclouds, param namespace publish/). We describe them here generically with prefix '*'.
  • diagnostic_period: How often the diagnostics should be published. Only whole seconds are supported.
  • */rate/desired: The expected publishing/receiving rate. publish/rate/desired is also used to configure the periodic publishing.
  • */rate/min/*/rate/max: The minimum/maximum expected publishing/receiving rate. If *_rate is set, it is used as a default value for these two.
  • */rate/tolerance: Real min rate is (*/rate/min * (1-tolerance)), real max rate is (*/rate/max * (1+tolerance)).
  • */rate/window_size: For how many updates (called once in diagnostic_period) should the topic statistics be stored. If you set the window too small, the computed rates will have high variance. Also, consider setting this to a higher value when the expected rate of the topic is lower than 1.
  • */delay/min/*/delay/max: Min/max allowed difference between current time and time in the processed message's header.

PassThrough (ImprovedFilter)

Transform pointclouds between frames with the possibility to crop them in one dimension.

Additional parameters:

• filter_limit_min/filter_limit_max: Min/max values for the filter.
• filter_field_name: Name of the pointcloud field to filter by.
• filter_limit_negative: If false, retain data inside the interval. If false, return the data that are outside.

CropBox (ImprovedFilter)

Transform pointclouds between frames with the possibility to crop them in all three dimensions.

Additional parameters:

• min_x/min_y/min_z/max_x/max_y/max_z/: Min/max corners of the crop box.
• negative: If false, retain data inside the cropbox. If false, return the data that are outside.