Basic Node Usage

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You always get PaCMaN Vision basic node (or bare-bone) regardless of the build configuration you adopted (see Build Instructions).

The basic node lets you apply some filters in real time to the stream of acquired point clouds coming from the Sensor Module and republish the modified stream into /pacman_vision/scene_processed topic. Filters actually implemented are:

• Cropping filter: Creates a bounding box with dimensions specified by `Cropping Filter Limits' and remove everything outside the bounds. You can optionally publish a marker (transparent red box) showing the filter limits.
• Downsampling filter: Applies a Voxel Grid filter to the stream (after the eventual cropping filter), effectively reducing the number of points in the cloud stream. The strength of the filter can be controlled in real time with downsampling leaf size parameter.
• Plane Segmentation: A common algorithm used in robotics, it finds a planar surface (usually the bigger there is) and removes points belonging to the plane from the stream of cloud. This is particularly useful in table-top scenarios, where you want to separate the table (plane) from the objects lying on it. Plane segmentation is the last filter applied, i.e. after the eventual cropping and downsampling.

Basic node, also provides saving and loading of configurations to/from yaml files, with the buttons provided in the Gui. Note that if you want to load a specific configuration from the launch file (not the Gui), yaml file must be stored into config subfolder of PaCMaN Vision.

Basic node gives you the ability to save a single processed point cloud from the stream into a pcd file on disk, this can be either done by calling the service /pacman_vision/get_scene_processed or by clicking the relative Gui button (which just calls the service for you).

Finally the Gui provides two button Master Disable and Master Reset:

• Master disable lets you pause all the functionality of the node, including modules, stopping cloud stream processing and consequently lowering cpu usage to near zero. The node however will remain registered on ROS network, so that, when you re-enable it again all the functionalities will resume as if nothing happened.
• Master reset lets you reset the node completely, killing all the modules and reloading the last loaded configuration.

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Basic Node Summary
/pacman_vision/processed_scene	topic	Republish filtered stream of point clouds
/pacman_vision/get_scene_processed	service	Get a single filtered point cloud and optionally save it to disk
/pacman_vision/markers	topic	Rviz Marker Array containing all the markers published by the node, including those published by other modules