Body Pose

Overview

Body pose is a 22-joint skeleton in the world frame: each joint has position (x, y, z in meters) and orientation (quaternion w, x, y, z). One message per frame, time-aligned with head and hand pose.

Coordinate Frame

• Reference frame: World.
• Axes: X forward, Y left, Z up (right-handed).
• Units: Position in meters.
• Orientation: Quaternion in w, x, y, z order.

Topic & Message Type

• Topic: /pose/body
• Message type: pose.BodyFrame
• Encoding: protobuf

BodyFrame uses pose_common for each joint: header plus 22 Transforms. The i-th joint is transforms[i] (index 0–21).

Message definition (body, one message per frame):

syntax = "proto3";

package pose;

import "common/header.proto";
import "pose/pose_common.proto";

message BodyFrame {
  .common.header.Header header = 1;
  repeated pose.common.Transform transforms = 2;
}

Transform type (from pose/pose_common.proto):

syntax = "proto3";

package pose.common;

message Quaternion {
  double w = 1;
  double x = 2;
  double y = 3;
  double z = 4;
}

message Transform {
  Quaternion quat = 1;
  double x = 2;
  double y = 3;
  double z = 4;
}

Joint Index and Conventions

22 joints (index 0–21). Joint indices and skeleton connectivity:

Index	Name	Index	Name
0	Pelvis	11	R_Foot
1	L_Hip	12	Neck
2	R_Hip	13	L_Collar
3	Spine_01	14	R_Collar
4	L_Knee	15	Head
5	R_Knee	16	L_Shoulder
6	Spine_02	17	R_Shoulder
7	L_Ankle	18	L_Elbow
8	R_Ankle	19	R_Elbow
9	Spine_03	20	L_Wrist
10	L_Foot	21	R_Wrist