How to stop ZED mini from publishing both tf and tf_static topics?

Antonis · December 13, 2022, 12:03pm

Hi everyone,

I have a ZED mini and I am using it through the zed_ros_wrappers. I am trying to find a way to disable the /tf topic that is being created when I subscribe to the /odom topic.

Although by using the launch file named zed_no_tf.launch the /tf topic returns empty and echoes nothing, the /tf_static still returns the static transformations of the camera frames.

Is there a way to stop publishing the /tf and /tf_static completely?

Thank you in advance.

Myzhar · December 13, 2022, 1:04pm

Hi @Antonis
you must set the publish_urdf launch parameter to false:

github.com

stereolabs/zed-ros-wrapper/blob/master/zed_wrapper/launch/zed_no_tf.launch#L34


      
          
          
<!-- Load SVO file -->
          <arg name="svo_file"              default="" /><!-- <arg name="svo_file" default="path/to/svo/file.svo"> -->
          <!-- Remote stream -->
          <arg name="stream"                default="" /> <!-- <arg name="stream" default="<ip_address>:<port>"> -->
          
          
<!-- Base frame -->
          <arg name="base_frame"            default="base_link" />
          
          
<!-- Publish ZED urdf -->
          <arg name="publish_urdf"          default="true" />
          
          
<arg name="camera_id"             default="0" />
          <arg name="gpu_id"                default="-1" />
          
          
<!-- Position respect to base frame (i.e. "base_link) -->
          <arg name="cam_pos_x"             default="0.0" />
          <arg name="cam_pos_y"             default="0.0" />
          <arg name="cam_pos_z"             default="0.0" />
          
          
<!-- Orientation respect to base frame (i.e. "base_link) -->

Antonis · December 13, 2022, 3:20pm

Hi @Myzhar,

thank you for taking the time again to respond to my issue. I notice that there is a drop in the frequency of the odometry topic when I set the URDF setting to false. Is there a way to overcome this ?

Myzhar · December 13, 2022, 3:47pm

That’s expected if there are no publishers for the required map → odom → base_link → camera_base_link TF chain.
The node when starts the positional tracking module it checks for TF and waits for them.
You can try to disable the Positional Tracking module:

github.com

stereolabs/zed-ros-wrapper/blob/master/zed_wrapper/params/common.yaml#L47


      
              extrinsic_in_camera_frame:  true                            # if `false` extrinsic parameter in `camera_info` will use ROS native frame (X FORWARD, Z UP) instead of the camera frame (Z FORWARD, Y DOWN) [`true` use old behavior as for version < v3.1]
          
          
depth:
              quality:                    1                               # '0': NONE, '1': PERFORMANCE, '2': QUALITY, '3': ULTRA, '4': NEURAL
              sensing_mode:               0                               # '0': STANDARD, '1': FILL (not use FILL for robotic applications)
              depth_stabilization:        1                               # `0`: disabled, `1`: enabled
              openni_depth_mode:          false                           # 'false': 32bit float meters, 'true': 16bit uchar millimeters
              depth_downsample_factor:    0.5                             # Resample factor for depth data matrices [0.01,1.0] The SDK works with native data sizes, but publishes rescaled matrices (depth map, point cloud, ...)
          
          
pos_tracking:
              pos_tracking_enabled:       true                            # True to enable positional tracking from start
              publish_tf:                 true                            # publish `odom -> base_link` TF
              publish_map_tf:             true                            # publish `map -> odom` TF
              map_frame:                  'map'                           # main frame
              odometry_frame:             'odom'                          # odometry frame
              area_memory_db_path:        'zed_area_memory.area'          # file loaded when the node starts to restore the "known visual features" map. 
              save_area_memory_db_on_exit: false                          # save the "known visual features" map when the node is correctly closed to the path indicated by `area_memory_db_path`
              area_memory:                true                            # Enable to detect loop closure
              floor_alignment:            false                           # Enable to automatically calculate camera/floor offset
              initial_base_pose:          [0.0,0.0,0.0, 0.0,0.0,0.0]      # Initial position of the `base_frame` -> [X, Y, Z, R, P, Y]
              init_odom_with_first_valid_pose: true                       # Enable to initialize the odometry with the first valid pose