Interfaces

Package mocap4r2_interfaces, repository mocap4r2_interfaces (they replace mocap4r2_msgs of 1.x; Open Robotics reserves the mocap_* names, so every MOCAP4ROS2 package starts with mocap4r2_).

Identifiers are stable: they come from the mocap system (never from the position in an array), so the same marker or body keeps its id from frame to frame. Validity is explicit: a body that is not tracked is published with tracking_valid: false and its last pose, never with zeros or NaN.

Marker

# A single 3D marker measured by a motion capture system.
# Positions are in the frame of the containing message header (Z-up, metres).

int32 UNKNOWN_ID=-1

# Stable identifier from the mocap SDK, or UNKNOWN_ID for unlabeled markers.
int32 id
# Label from the mocap software (e.g. "robot1:front_left"), empty if unlabeled.
string name
geometry_msgs/Point position
# True when the marker is not seen in this frame; position then holds the last estimate.
bool occluded
# Reconstruction residual in metres, negative if unknown.
float32 residual

Markers

# All markers of one mocap frame.

std_msgs/Header header
# Frame number reported by the mocap system (shared with RigidBodies/Skeletons of the same frame).
uint64 frame_number
Marker[] markers

RigidBody

# A tracked rigid body (asset, subject, 6DOF body) of a motion capture system.

int32 UNKNOWN_ID=-1

# Stable identifier from the mocap SDK, or UNKNOWN_ID.
int32 id
# Name given in the mocap software.
string name
# False when the body is not tracked in this frame; pose must not be used then.
bool tracking_valid
# Pose of the body frame in the header frame.
geometry_msgs/Pose pose
# Mean marker error in metres, negative if unknown.
float32 mean_error
# Markers of the body as measured in this frame, in the header frame.
Marker[] markers

RigidBodies

# All rigid bodies of one mocap frame.

std_msgs/Header header
# Frame number reported by the mocap system (shared with Markers/Skeletons of the same frame).
uint64 frame_number
RigidBody[] rigid_bodies

Segment

# One segment (bone) of a skeleton.

int32 NO_PARENT=-1

int32 id
string name
# Id of the parent segment, or NO_PARENT for the root.
int32 parent_id
# False when the segment is not tracked in this frame.
bool tracking_valid
# Pose of the segment in the header frame.
geometry_msgs/Pose pose

Skeleton

# An articulated body (human or robot skeleton) tracked by a motion capture system.

int32 UNKNOWN_ID=-1

int32 id
string name
bool tracking_valid
Segment[] segments

Skeletons

# All skeletons of one mocap frame.

std_msgs/Header header
# Frame number reported by the mocap system (shared with Markers/RigidBodies of the same frame).
uint64 frame_number
Skeleton[] skeletons

MocapSystemInfo

# Announcement of a mocap system (driver) on /mocap4r2/systems (transient local).

# Fully qualified node name of the driver, used as the system id.
string system
# Kind of system: "optitrack", "vicon", "qualisys", "gazebo", "sim", ...
string type
# Frame of the published data.
string frame_id
# Nominal frame rate in Hz, 0 if unknown.
float64 frame_rate
# Current lifecycle state of the driver.
lifecycle_msgs/State state
# Capture session of the last START request, empty if none.
string session_id
# Fully qualified topics published by the system and their types.
string[] topics
string[] topic_types

Control

# Request to start or stop mocap systems, published on /mocap4r2/control.

uint8 START=0
uint8 STOP=1

uint8 command
# Unique id of this request, echoed in every ControlAck.
string request_id
# Capture session this request belongs to (e.g. a trial name), may be empty.
string session_id
# Fully qualified node name of the requester.
string requester
# Systems addressed (fully qualified node names); empty means all systems.
string[] systems
builtin_interfaces/Time stamp

ControlAck

# Answer of a mocap system to a Control request, published on /mocap4r2/control_ack.

string request_id
string session_id
# Fully qualified node name of the answering system.
string system
# Command being answered (Control.START / Control.STOP).
uint8 command
# True if the system reached the requested state.
bool success
# Reason when success is false.
string message
# Time at which the system reached the requested state.
builtin_interfaces/Time stamp

TrajectoryError

# Error of a robot pose estimate against the mocap ground truth.

std_msgs/Header header
# Associated pose pairs used.
uint32 samples
# Absolute trajectory error, metres (after alignment if aligned is true).
float64 ate_rmse
float64 ate_mean
float64 ate_max
# Relative pose error over the configured step: metres and radians.
float64 rpe_trans_rmse
float64 rpe_rot_rmse
bool aligned
# Alignment from the estimate frame to the ground-truth frame.
geometry_msgs/Pose alignment

SetOrigin (service)

# Set the origin of a ground-truth frame.
# If use_current is true, the current pose becomes the origin and origin is ignored.

bool use_current
geometry_msgs/Pose origin
---
bool success
string message