feat(jetson): AprilTag landmark detector — DICT_APRILTAG_36h11 (issue #191)
saltybot_apriltag_msgs (ament_cmake):
• DetectedTag.msg — tag_id, family, decision_margin, corners[8],
center, 6-DOF pose + pose_valid flag
• DetectedTagArray.msg — DetectedTag[], count
saltybot_apriltag (ament_python, single node):
• _aruco_utils.py — ROS2-free: ArucoBackend (cv2 4.6/4.7+ API shim),
rvec_tvec_to_pose (Rodrigues → Shepperd quaternion)
• apriltag_node.py — 10 Hz timer; subscribes image + latched camera_info;
cv2.solvePnP IPPE_SQUARE for 6-DOF pose when K
available; publishes /saltybot/apriltags
• test/test_apriltag.py — 11 unit tests (11/11 pass, no ROS2 needed):
pose math + rendered tag detection + multi-tag
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-perception
d6d7e7b75a