Geometry Messages (C++)

Spatial types in horus::msg::. Include via <horus/msg/geometry.hpp>.

Quick Reference

Type	Size	Key Fields	Use Case
`Twist`	56 B	`linear[3]`, `angular[3]`	3D velocity
`Pose2D`	32 B	`x`, `y`, `theta`	2D robot pose
`Pose3D`	64 B	`position` (Point3), `orientation` (Quaternion)	3D pose
`Point3`	24 B	`x`, `y`, `z`	3D point
`Vector3`	24 B	`x`, `y`, `z`	3D vector
`Quaternion`	32 B	`x`, `y`, `z`, `w`	3D rotation
`TransformStamped`	64 B	`translation[3]`, `rotation[4]`	TF tree data
`PoseStamped`	104 B	`Pose3D` + `frame_id[32]` + `timestamp_ns`	Timestamped pose
`PoseWithCovariance`	392 B	`Pose3D` + `covariance[36]` + `frame_id[32]` + `timestamp_ns`	Uncertain pose
`TwistWithCovariance`	384 B	`Twist` + `covariance[36]` + `frame_id[32]` + `timestamp_ns`	Uncertain velocity
`Accel`	56 B	`linear[3]`, `angular[3]`	3D acceleration
`AccelStamped`	96 B	`Accel` + `frame_id[32]` + `timestamp_ns`	Timestamped accel

Twist — 3D Velocity

horus::msg::Twist twist{};
twist.linear[0] = 0.5;   // vx (m/s) — forward
twist.linear[1] = 0.0;   // vy — lateral (holonomic only)
twist.linear[2] = 0.0;   // vz — vertical
twist.angular[0] = 0.0;  // roll rate (rad/s)
twist.angular[1] = 0.0;  // pitch rate
twist.angular[2] = 0.3;  // yaw rate
twist.timestamp_ns = 0;

Pose2D — 2D Robot Position

The simplest pose — x, y, heading:

horus::msg::Pose2D pose{};
pose.x = 1.5;        // meters
pose.y = 2.0;        // meters
pose.theta = 0.785;  // radians (45 degrees)
pose.timestamp_ns = 0;

Quaternion — 3D Rotation

Always normalize. w=1, x=y=z=0 is identity (no rotation):

horus::msg::Quaternion q{};
q.x = 0.0; q.y = 0.0; q.z = 0.0; q.w = 1.0;  // identity

// 90° rotation around Z axis:
q.x = 0.0; q.y = 0.0; q.z = 0.7071; q.w = 0.7071;

TransformStamped — TF Transform Message

The wire/message form of a TF transform — publishable on a topic. Note TransformFrame itself uses its own horus::Transform struct (std::array<double,3> translation, std::array<double,4> rotation), not this message type:

horus::msg::TransformStamped tf{};
tf.translation[0] = 0.2;   // x offset (meters)
tf.translation[1] = 0.0;
tf.translation[2] = 0.3;   // z offset (height)
tf.rotation[0] = 0.0;      // qx
tf.rotation[1] = 0.0;      // qy
tf.rotation[2] = 0.0;      // qz
tf.rotation[3] = 1.0;      // qw (identity)
tf.timestamp_ns = 0;

Odometry Uses Pose2D + Twist

// Odometry combines position and velocity:
auto odom = sub_->recv();
if (odom) {
    double x = odom->get()->pose.x;
    double y = odom->get()->pose.y;
    double heading = odom->get()->pose.theta;
    double vx = odom->get()->twist.linear[0];
    double wz = odom->get()->twist.angular[2];
}