The proper way to define a TF tree

edit

Hi. I have two nodes: (1) the SLAM node, and (2) the Rtab-map node, which requires - for my case - (a) stereo images msg and (b) its respective configs msg; (c) odometry msg and (d) the transformation tree map->odom->base_link->camera_link. I'm sending all from:

Node (1): publishing odometry msg, images msg, and configs msg

odom_msg_->header.stamp = node->now();
odom_msg_->header.frame_id = "odom";
odom_msg_->child_frame_id = "base_link";
//...data...
odometry_pub_->publish(odom_msg_);
// ...data...
left_image_msg->header.frame_id = "camera_link";
right_image_msg->header.frame_id = "camera_link";
left_config.header.frame_id = "camera_link";
right_config.header.frame_id = "camera_link";

Node (1): publishing the TF (odom -> base_link)

tf2_ros::TransformBroadcaster odom_broadcaster(node);
odom_trans.header.stamp = odom_msg_->header.stamp;
odom_trans.header.frame_id = "odom";
odom_trans.child_frame_id = "base_link";
//...data...
odom_broadcaster.sendTransform(odom_trans);

Node (2): in the launch file I relate base_link->camera_link

 Node(
        package='tf2_ros', node_executable='static_transform_publisher',
        arguments=["0.0", "0.0", "0.0", -1.57", "0.0", "-1.57", "base_link", "camera_link"),

It is important to say that frame_id is set to base_link. And in RVIZ, I set map as the global fixed frame.

When I run the node (1) and (2) I can see (via RVIZ) the transformation tree as supposed to be. Then, I also debbuged used tf2_echo:

 ros2 run tf2_ros tf2_echo map odom
 At time 1603749986.677481295
 - Translation: [0.000, 0.000, 0.000]
 - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]

 ros2 run tf2_ros tf2_echo odom base_link
 At time 1603750227.448060361
 - Translation: [-0.005, 0.511, 0.000]
 - Rotation: in Quaternion [0.004, -0.003, 0.704, 0.710]

 ros2 run tf2_ros tf2_echo base_link camera_link
 At time 0.0
 - Translation: [0.000, 0.000, 0.000]
 - Rotation: in Quaternion [0.500, -0.500, 0.500, 0.500]

Node (2) does not show errors, just this warning:

 [ WARN] (2020-10-26 15:10:34.345) MsgConversion.cpp:1385::getTransform() (getting transform odom -> base_link) Lookup would require extrapolation into the future.  Requested time 1603750229.45627 but the latest data is at time 1603750227.74125, when looking up transform from frame [base_link] to frame [odom]