rtabmap_ros/rtabmap_util/doc/point_cloud_xyz.md

point_cloud_xyz

Projects a depth or disparity image into a point cloud.

The node takes a depth image and its calibration and produces a sensor_msgs/msg/PointCloud2, with optional decimation, range limits, voxel and radius filtering, and normal estimation — the same preprocessing RTAB-Map would do internally, done once and shared.

depth_image_proc's own point_cloud_xyz does the bare projection; this node exists for the filtering, and for accepting disparity directly.

See point_cloud_xyzrgb for the colored equivalent.

Contents

• Usage
• Subscribed Topics
• Published Topics
• Parameters
• Organized output
• Notes

Usage

ros2 run rtabmap_util point_cloud_xyz --ros-args \
  -r depth/image:=/camera/depth/image_raw \
  -r depth/camera_info:=/camera/depth/camera_info \
  -p decimation:=4 -p max_depth:=5.0 -p voxel_size:=0.05

ComposableNode(
    package='rtabmap_util',
    plugin='rtabmap_util::PointCloudXYZ',
    name='point_cloud_xyz',
    parameters=[{'decimation': 4, 'max_depth': 5.0, 'voxel_size': 0.05}],
    remappings=[('depth/image', '/camera/depth/image_raw'),
                ('depth/camera_info', '/camera/depth/camera_info')])

Subscribed Topics

The node listens on two independent input sets and uses whichever one is being published. Only one of them should be connected.

Depth

Topic	Type	Description
depth/image	sensor_msgs/msg/Image	32FC1 (meters), 16UC1 (millimeters) or mono16. Goes through image_transport, see depth_transport parameter below.
depth/camera_info	sensor_msgs/msg/CameraInfo

Disparity

Topic	Type	Description
disparity/image	stereo_msgs/msg/DisparityImage	32FC1 or 16SC1. The 16-bit form is fixed point, 16 units per pixel of disparity.
disparity/camera_info	sensor_msgs/msg/CameraInfo

Published Topics

Topic	Type	Description
cloud	sensor_msgs/msg/PointCloud2	In the frame of the input image, stamped with it. Carries normal_* fields when normals are enabled.

Nothing is computed unless cloud has a subscriber.

Parameters

Synchronization

Parameter	Type	Default	Description
approx_sync	bool	true	Match image and camera info by nearest stamp. Set false when they are published with identical stamps, which is stricter and cheaper.
approx_sync_max_interval	double	0.0	With approx_sync, reject pairs further apart than this many seconds. 0 disables the check.
topic_queue_size	int	1	Queue depth of each input subscription.
sync_queue_size	int	10	Queue depth of the synchronizer.
qos	int	0	Reliability of the image and disparity subscriptions: 0 system default, 1 reliable, 2 best effort.
qos_camera_info	int	value of qos	Reliability of the camera info subscriptions.
depth_transport	string	"raw"	image_transport plugin for depth/image, e.g. compressedDepth.

Projection and filtering, applied in this order

Parameter	Type	Default	Description
decimation	int	1	Keep one pixel in decimation, in each direction. 2 gives a quarter of the points. The image dimensions must divide by it.
roi_ratios	string	""	Crop before projecting, as four ratios "left right top bottom", e.g. "0.1 0.1 0 0.2".
min_depth	double	0.0	Discard points nearer than this, in meters. 0 disables.
max_depth	double	0.0	Discard points further than this, in meters. 0 disables.
voxel_size	double	0.0	Downsample to one point per voxel of this size, in meters. 0 disables.
noise_filter_radius	double	0.0	Radius outlier removal, in meters. 0 disables.
noise_filter_min_neighbors	int	5	Neighbors a point needs within noise_filter_radius to survive.
normal_k	int	0	Estimate normals from this many nearest neighbors. 0 disables.
normal_radius	double	0.0	Estimate normals from all neighbors within this radius, in meters. 0 disables.
filter_nans	bool	false	See Organized output.

Organized output

By default the cloud stays organized: one point per pixel, in image order, with out-of-range points set to NaN rather than removed. That layout is what lets consumers treat the cloud as an image, and it is why a cloud with max_depth set still reports the full point count.

Set filter_nans to true to drop the invalid points instead. The cloud becomes unorganized and its size reflects what is actually in range — including being empty when nothing is.

Voxel and radius filtering also produce unorganized clouds, since both remove points.

Notes

decimation is by far the cheapest way to cut the cost of everything downstream, and on a depth image it loses very little: neighboring pixels of a surface are nearly redundant. Reach for it before voxel_size.