ROS 2 - ZED Stereo Node

The easiest way to start a ZED ROS 2 node for a stereo camera is by using the command line:

ros2 launch zed_wrapper zed_camera.launch.py camera_model:=<camera model>

where <camera model> must be replaced with one in the list zed, zedm, zed2, zed2i, zedx, and zedxm.

Published Topics #

The ZED node publishes data to the following topics:

Left camera
- ~/left/camera_info: Left camera calibration data.
- ~/left/image_rect_color: Left camera color rectified image.
- ~/left_gray/image_rect_gray: Left camera gray rectified image.
- ~/left_raw/camera_info: Left camera raw calibration data.
- ~/left_raw/image_rect_color: Left camera color unrectified image.
- ~/left_raw_gray/image_rect_gray: Left camera gray unrectified image.
- ~/rgb/camera_info: RGB calibration data.
- ~/rgb/image_rect_color: RGB color rectified image.
- ~/rgb_gray/image_rect_gray: RGB gray rectified image.
- ~/rgb_raw/camera_info: RGB raw calibration data.
- ~/rgb_raw/image_rect_color: RGB color unrectified image.
- ~/rgb_raw_gray/image_rect_gray: RGB gray unrectified image.
Right camera
- ~/right/camera_info: Right camera calibration data.
- ~/right/image_rect_color: Right camera color rectified image.
- ~/right_gray/image_rect_gray: Right camera gray rectified image.
- ~/right_raw/camera_info: Right camera raw calibration data.
- ~/right_raw/image_rect_color: Right camera color unrectified image.
- ~/right_raw_gray/image_rect_gray: Right camera gray unrectified image.
Stereo pair
- ~/stereo/image_rect_color: side-by-side left/right rectified stereo pair. Calibration data are available in the topics: ~/left/camera_info and ~/right/camera_info.
- ~/stereo_raw/image_raw_color: side-by-side left/right unrectified stereo pair. Calibration data are available in the topics: ~/left_raw/camera_info and ~/right_raw/camera_info.
Depth and point cloud
- ~/depth/camera_info: Depth camera calibration data.
- ~/depth/depth_registered: Depth map image registered on left image.
- ~/depth/depth_info: minimum and maximum depth information (custom message).
- ~/point_cloud/cloud_registered: Registered color point cloud.
- ~/confidence/confidence_map: Confidence image (doubleing point values).
- ~/disparity/disparity_image: Disparity image.
Sensors data
- ~/left_cam_imu_transform: Transform from the left camera sensor to the IMU sensor.
- ~/imu/data: Accelerometer, gyroscope, and orientation data in Earth frame.
- ~/imu/data_raw: Accelerometer and gyroscope data in Earth frame.
- ~/imu/mag: Raw magnetometer data (only ZED 2 and ZED 2i).
- ~/atm_press: atmospheric pressure (only ZED 2 and ZED 2i).
- ~/temperature/imu: temperature measured by the IMU sensor.
- ~/temperature/left: temperature measured near the left CMOS sensor (only ZED 2 and ZED 2i).
- ~/temperature/right: temperature measured near the right CMOS sensor (only ZED 2 and ZED 2i).
Positional tracking
- ~/pose: Absolute 3D position and orientation relative to the Map frame (Sensor Fusion algorithm + SLAM).
- ~/pose/status: the status of the positional tracking module (custom message).
- ~/pose_with_covariance: Camera pose referred to Map frame with covariance.
- ~/odom: Absolute 3D position and orientation relative to the Odometry frame (pure visual odometry for ZED, visual-inertial odometry for ZED Mini).
- ~/odom/status: the status of the odometry from the positional tracking module (custom message).
- ~/path_map: Sequence of camera poses in Map frame.
- ~/path_odom: Sequence of camera odometry poses in Map frame.
Geo Tracking
- ~/pose/filtered: the GNSS fused pose of the robot
- ~/pose/filtered/status: the status of the GNSS fused pose (custom message).
- ~/geo_pose/: the Latitude/Longitude pose of the robot
- ~/geo_pose/status: the status of the Latitude/Longitude pose (custom message).
3D Mapping
- ~/mapping/fused_cloud: Fused point cloud created when the enable_mapping service is called.
Object Detection
- ~/obj_det/objects: detected objects (custom message).
Body Tracking
- ~/body_trk/skeletons: detected body skeletons (custom message).
Plane Detection
- ~/plane: Detected plane (custom message).
- ~/plane_marker: Detected plane object to be displayed on RVIZ 2.

📌 Note: Each topic has a common prefix created by the launch file as ~ = /<namespace>/<node_name>/, where <namespace> is replaced with the value of the parameter camera_name and <node_name> is the name of the node, e.g. zed_node.

Image Transport #

The ROS 2 wrapper supports the stack image_transport introduced with ROS 2 Crystal Clemmys.

All the image topics are published using the image_transport::CameraPublisher object, that correctly associates the sensor_msgs::msg::CameraInfo message to the relative sensor_msg::msg::Image message and creates the relative compressed image streams.

QoS profiles #

All the topics are configured by default to use the following ROS 2 QoS profile:

Reliability: RELIABLE
History (Depth): KEEP_LAST (10)
Durability: VOLATILE
Lifespan: Infinite
Deadline: Infinite
Liveliness: AUTOMATIC
Liveliness lease duration: Infinite

📌 Note: Read the official ROS 2 documentation about the QoS and the relatived settings for details.

The QoS settings can be modified by changing the relative parameters in the YAML files, as described in this official ROS 2 design document.

When creating a subscriber, be sure to use a compatible QOS profile according to the following tables:

Compatibility of QoS durability profiles:

Publisher	Subscriber	Connection	Result
Volatile	Volatile	Yes	Volatile
Volatile	Transient local	No	-
Transient local	Volatile	Yes	Volatile
Transient local	Transient local	Yes	Transient local

Compatibility of QoS reliability profiles:

Publisher	Subscriber	Connection	Result
Best effort	Best effort	Yes	Best effort
Best effort	Reliable	No	-
Reliable	Best effort	Yes	Best effort
Reliable	Reliable	Yes	Reliable

In order for a connection to be made, all of the policies that affect compatibility must be compatible. For instance, if a publisher-subscriber pair has compatible reliability QoS profiles, but incompatible durability QoS profiles, the connection will not be made.

📌 Note: for a detailed list of all the compatibility settings, please refer to the official ROS 2 documentation.

Configuration parameters #

Specify your launch parameters in the common_stereo.yaml, zed.yaml, zedm.yaml, zed2.yaml, zed2i.yaml, zedx.yaml, zedxm.yaml, and virtual files available in the folder zed_wrapper/config.

General parameters #

Namespace: general

common_stereo.yaml

Parameter	Description	Value
camera_timeout_sec	Camera timeout (sec) if communication fails	int
camera_max_reconnect	Reconnection temptatives after timeout, before shutting down	int
camera_flip	Flip the camera data if it is mounted upsidedown	`true`, `false`
serial_number	Select a ZED camera by its Serial Number	int
pub_resolution	The resolution used for output. ‘NATIVE’ to use the same `general.grab_resolution` - `CUSTOM` to apply the `general.pub_downscale_factor` downscale factory to reduce bandwidth in transmission	string,‘NATIVE’‘SVGA’, ‘VGA’, ‘LOW’
pub_downscale_factor	Rescale factor used to rescale image before publishing when ‘pub_resolution’ is ‘CUSTOM’	double
pub_frame_rate^*	Set the video/depth publish rate	double
gpu_id	Select a GPU device for depth computation	int
optional_opencv_calibration_file	Optional path where the ZED SDK can find a file containing the calibration information of the camera computed by OpenCV.	string

^* Dynamic parameter

zed.yaml, zedm.yaml, zed2.yaml, zed2i.yaml, zedx.yaml, zedxm.yaml, and virtual.yaml

Parameter	Description	Value
camera_model	Type of Stereolabs camera	string, `zed`, `zedm`, `zed2`, `zed2i`, `zedx`, `zedxm`, `virtual`
camera_name	User name for the camera, can be different from camera model	string
grab_resolution	The native camera grab resolution.	string, ‘HD2K’, ‘HD1200’,‘HD1080’, ‘HD720’, ‘SVGA’, ‘VGA’, ‘AUTO’
grab_frame_rate	ZED SDK internal grabbing rate	int, ‘15’,‘30’,‘60’,‘90’,‘100’,‘120’

SVO input parameters #

Namespace: svo

common_stereo.yaml

Parameter	Description	Value
svo_path	Specify SVO filename	string, Note: relative file paths are not allowed
svo_loop	Restart the SVO if the end of the file is reached	`true`, `false`
svo_realtime	if true SVO will be played trying to respect the original framerate eventually skipping frames, otherwise every frame will be processed respecting the `pub_frame_rate` setting	`true`, `false`

Streaming input parameters #

Namespace: stream

common_stereo.yaml

Parameter	Description	Value
stream_address	Address of the local streaming server	string
stream_port	Port of the local streaming server (only odd values are valid)	int

Simulation input parameters #

Namespace: simulation

common_stereo.yaml

Parameter	Description	Value
sim_enabled	Enable simulation input	`true`, `false`
sim_address	Address of the simulation server	string
sim_port	Port of the simulation server (only odd values are valid)	int

Streaming server parameters #

Namespace: stream_server

common_stereo.yaml

Parameter	Description	Value
stream_enabled	enable the streaming server when the camera is open	`true`, `false`
codec	ifferent encoding types for image streaming: ‘H264’, ‘H265’	string
port	Port used for streaming. Port must be an even number. Any odd number will be rejected.	int
bitrate	Streaming bitrate (in Kbits/s) used for streaming. See doc	int, [1000 - 60000]
gop_size	The GOP size determines the maximum distance between IDR/I-frames. Very high GOP size will result in slightly more efficient compression, especially on static scenes. But latency will increase.	int, [max 256]
adaptative_bitrate	Bitrate will be adjusted depending the number of packet dropped during streaming. If activated, the bitrate can vary between [bitrate/4, bitrate].	`true`, `false`
chunk_size	Stream buffers are divided into X number of chunks where each chunk is chunk_size bytes long. You can lower chunk_size value if network generates a lot of packet lost: this will generates more chunk for a single image, but each chunk sent will be lighter to avoid inside-chunk corruption. Increasing this value can decrease latency.	int, [1024 - 65000]
target_framerate	Framerate for the streaming output. This framerate must be below or equal to the camera framerate. Allowed framerates are 15, 30, 60 or 100 if possible. Any other values will be discarded and camera FPS will be taken.	int

Video parameters #

Namespace: video

common_stereo.yaml

Parameter	Description	Value
brightness^*	Image brightness	int, [0,8]
contrast^*	Image contrast	int, [0,8]
hue^*	Image hue	int, [0,11]
saturation^*	Image saturation	int, [0,8]
sharpness^*	Image sharpness	int, [0,8]
gamma^*	Image gamma	int, [0,8]
auto_exposure_gain^*	Enable the auto exposure and auto gain	`true`, `false`
exposure^*	Exposure value if `auto-exposure` is false	int [0,100]
gain^*	Gain value if `auto-exposure` is false	int [0,100]
auto_whitebalance^*	Enable the auto white balance	`true`, `false`
whitebalance_temperature^*	White balance temperature	int [28,65]

^* Dynamic parameter

zedx.yaml, zedxm.yaml, and virtual.yaml

Parameter	Description	Value
exposure_time^*	Defines the real exposure time in microseconds. Recommended to control manual exposure (instead of `video.exposure` setting)	int, [28,30000]
auto_exposure_time_range_min^*	Defines the minimum range of exposure auto control in micro seconds	int
auto_exposure_time_range_max^*	Defines the maximum range of exposure auto control in micro seconds	int
exposure_compensation^*	Defines the Exposure-target compensation made after auto exposure. Reduces the overall illumination target by factor of F-stops.	int, [0 - 100]
analog_gain^*	Defines the real analog gain (sensor) in mDB. Recommended to control manual sensor gain (instead of `video.gain` setting)	int, [1000-16000].
auto_analog_gain_range_min^*	Defines the minimum range of sensor gain in automatic control	int
auto_analog_gain_range_max^*	Defines the maximum range of sensor gain in automatic control	int
digital_gain^*	Defines the real digital gain (ISP) as a factor. Recommended to control manual ISP gain (instead of `video.gain` setting)	int, [1-256]
auto_digital_gain_range_min^*	Defines the minimum range of digital ISP gain in automatic control	int
auto_digital_gain_range_max^*	Defines the maximum range of digital ISP gain in automatic control	int
denoising^*	Defines the level of denoising applied on both left and right images	int, [0-100]

^* Dynamic parameter

Region of Interest parameters #

Namespace: region_of_interest

common_stereo.yaml

Parameter	Description	Value
automatic_roi	Enable the automatic ROI generation to automatically detect part of the robot in the FoV and remove them from the processing. Note: if enabled the value of `manual_polygon` is ignored	`true`, `false`
depth_far_threshold_meters	Filtering how far object in the ROI should be considered, this is useful for a vehicle for instance	double
image_height_ratio_cutoff	By default consider only the lower half of the image, can be useful to filter out the sky	double
manual_polygon	A polygon defining the ROI where the ZED SDK perform the processing ignoring the rest. Coordinates must be normalized to ‘1.0’ to be resolution independent.	string
apply_to_depth	Apply ROI to depth processing	`true`, `false`
apply_to_positional_tracking	Apply ROI to positional tracking processing	`true`, `false`
apply_to_object_detection	Apply ROI to object detection processing	`true`, `false`
apply_to_body_tracking	Apply ROI to body tracking processing	`true`, `false`
apply_to_spatial_mapping	Apply ROI to spatial mapping processing	`true`, `false`

Depth parameters #

Namespace: depth

common_stereo.yaml

Parameter	Description	Value
depth_mode	Select depth map quality	string, ‘NONE’, ‘PERFORMANCE’, ‘QUALITY’, ‘ULTRA’, ‘NEURAL’
depth_stabilization	Enable depth stabilization. Stabilizing the depth requires an additional computation load as it enables tracking	int, [0,100]
openni_depth_mode	Enable/disable the depth OpenNI format (16 bit, millimeters)	int, [0,1]
point_cloud_freq^*	frequency of the pointcloud publishing (equal or less to `grab_frame_rate` value)	double
depth_confidence^*	Depth confidence threshold (lower values = more filtering)	int [0,100]
depth_texture_conf^*	Depth tectureconfidence threshold (lower values = more filtering)	int [0,100]
remove_saturated_areas^*	If true color saturated areas are not included in the depth map	`true`, `false`

📌 Note: To disable depth calculation set quality to NONE. All the other parameters relative to depth will be ignored and only the video streams and sensors data will be published.

^* Dynamic parameter

zed.yaml, zedm.yaml, zed2.yaml, zed2i.yaml, zedx.yaml, zedxm.yaml, and virtual.yaml

Parameter	Description	Value
min_depth	Minimum depth value (from the camera) that will be computed	double
max_depth	Maximum range allowed for depth. Values beyond this limit will be reported as TOO_FAR	double, ]0.0,20.0]

^* Dynamic parameter

Positional tracking parameters (Odometry and Localization) #

Namespace: pos_tracking

common_stereo.yaml

Parameter	Description	Value
pos_tracking_enabled	Enable positional tracking when the node starts	`true`, `false`
pos_tracking_mode	Use `GEN_1` for old behaviors, `GEN_2` for the new algorithm	string, ‘GEN_1’, ‘GEN_2’
imu_fusion	Enable IMU fusion. When set to false, only the optical odometry will be used.	`true`, `false`
publish_tf	Enable publishing of transform `odom` -> `base_link` and all the other transforms	`true`, `false`
publish_map_tf	Enable publishing of transform `map` -> `odom`. Only valid if `publish_tf` is true	`true`, `false`
map_frame	Frame_id of the pose message	string
odometry_frame	Frame_id of the odom message	string
area_memory_db_path	The full path of the space memory DB	string
area_memory	Enable Loop Closing algorithm	`true`, `false`
reset_odom_with_loop_closure	Enable the automatic reset of the odometry when a loop closure event is detected.	`true`, `false`
depth_min_range	Set this value for removing fixed zones of the robot in the FoV of the camerafrom the visual odometry evaluation	double
set_as_static	If ’true’ the camera will be static and not move in the environment	`true`, `false`
set_gravity_as_origin	If ’true’ align the positional tracking world to imu gravity measurement. Keep the yaw from the user initial pose.	`true`, `false`
floor_alignment	Indicates if the floor must be used as origin for height measures	`true`, `false`
initial_base_pose	Initial reference pose. Useful if the `base_link` does not start from the origin	array
path_pub_rate	Frequency (Hz) of publishing of the path messages	double
path_max_count	Maximum number of poses kept in the pose arrays (-1 for infinite)	int
two_d_mode	Enable if robot moves on a planar surface. Forces Z to `fixed_z_value`, roll and pitch to zero	`true`, `false`
fixed_z_value	Fixed value assigned to Z coordinate if `two_d_mode` is true	double
transform_time_offset	The value added to the timestamp of `map->odom` and `odom->base_link` transform being generated	double

Global Localization (GNSS Fusion) #

Namespace: gnss_fusion

common_stereo.yaml

Parameter	Description	Value
gnss_fusion_enabled	Enable the fusion of ‘sensor_msg/NavSatFix’ message information into pose data	`true`, `false`
gnss_fix_topic	Name of the GNSS topic of type NavSatFix to subscribe [Default: “/gps/fix”]	string
gnss_zero_altitude	Set to `true` to ignore GNSS altitude information	`true`, `false`
h_covariance_mul	Multiplier factor to be applied to horizontal covariance of the received fix (plane X/Y)	double
v_covariance_mul	Multiplier factor to be applied to vertical covariance of the received fix (Z axis)	double
gnss_frame	The TF frame of the GNSS sensor [Default: “gnss_link”]	string
publish_utm_tf	Publish `utm` -> `map` TF	`true`, `false`
broadcast_utm_transform_as_parent_frame	If ’true’ publish `utm` -> `map` TF, otherwise `map` -> `utm`	`true`, `false`
enable_reinitialization	Determines whether reinitialization should be performed between GNSS and VIO fusion when a significant disparity is detected between GNSS data and the current fusion data. It becomes particularly crucial during prolonged GNSS signal loss scenarios.	`true`, `false`
enable_rolling_calibration	If this parameter is set to true, the fusion algorithm will used a rough VIO / GNSS calibration at first and then refine it. This allow you to quickly get a fused position	`true`, `false`
enable_translation_uncertainty_target	When this parameter is enabled (set to true), the calibration process between GNSS and VIO accounts for the uncertainty in the determined translation, thereby facilitating the calibration termination. The maximum allowable uncertainty is controlled by the ’target_translation_uncertainty’ parameter	`true`, `false`
gnss_vio_reinit_threshold	Determines the threshold for GNSS/VIO reinitialization. If the fused position deviates beyond out of the region defined by the product of the GNSS covariance and the gnss_vio_reinit_threshold, a reinitialization will be triggered	double
target_translation_uncertainty	Defines the target translation uncertainty at which the calibration process between GNSS and VIO concludes. By default, the threshold is set at 10 centimeters.	double
target_yaw_uncertainty	Defines the target yaw uncertainty at which the calibration process between GNSS and VIO concludes. The unit of this parameter is in radian. By default, the threshold is set at 0.1 radians	double

Mapping parameters #

Namespace: mapping

common_stereo.yaml

Parameter	Description	Value
mapping_enabled	Enable/disable the mapping module	`true`, `false`
resolution	Resolution of the fused point cloud [0.01, 0.2]	double, default=`0.1`
max_mapping_range	Maximum depth range while mapping in meters (-1 for automatic calculation) [2.0, 20.0]	double
fused_pointcloud_freq	Publishing frequency (Hz) of the 3D map as fused point cloud	double
clicked_point_topic	Topic published by Rviz when a point of the cloud is clicked. Used for plane detection	string, default `"/clicked_point"`

### Sensors parameters

Namespace: sensors

common_stereo.yaml

Parameter	Description	Value
publish_imu_tf	Enable publishing of transform `imu_link` -> `left_camera_frame`.	`true`, `false`
sensors_image_sync	Synchronize Sensors messages with latest published video/depth message	`true`, `false`
sensors_pub_rate:	Frequency of publishing of sensors data. MAX: 400. - MIN: grab rate	double

Object detection parameters #

Namespace: object_detection

common_stereo.yaml

Parameter	Description	Value
od_enabled	Automatically enables Object Detection when the node starts	`true`, `false`
model	Detection model	string, ‘MULTI_CLASS_BOX_FAST’, ‘MULTI_CLASS_BOX_MEDIUM’, ‘MULTI_CLASS_BOX_ACCURATE’, ‘PERSON_HEAD_BOX_FAST’, ‘PERSON_HEAD_BOX_ACCURATE’, ‘CUSTOM_YOLOLIKE_BOX_OBJECTS’
custom_onnx_file	Only used if ‘model’ is ‘CUSTOM_YOLOLIKE_BOX_OBJECTS’. Path to the YOLO-like ONNX file for custom object detection directly performed by the ZED SDK.	string
custom_onnx_input_size	Resolution used with the YOLO-like ONNX file. For example, 512 means a input tensor “1x3x512x512”	int
custom_label_yaml	Only used if ‘model’ is ‘CUSTOM_YOLOLIKE_BOX_OBJECTS’. Path to the COCO-like YAML file storing the custom class labels.	string
allow_reduced_precision_inference	Allow inference to run at a lower precision to improve runtime and memory usage	`true`, `false`
max_range	Defines a upper depth range for detections [m]	double
confidence_threshold^*	Minimum value of the detection confidence of an object	double, [0,99]
prediction_timeout	During this time [sec], the object will have OK state even if it is not detected. Set this parameter to 0 to disable SDK predictions	double
filtering_mode	Defines the filtering mode that should be applied to raw detections.	‘0’: NONE - ‘1’: NMS3D - ‘2’: NMS3D_PER_CLASS
mc_people^*	Enable people detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_vehicle^*	Enable vehicles detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_bag^*	Enable bags detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_animal^*	Enable animals detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_electronics^*	Enable electronic devices detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_fruit_vegetable^*	Enable fruits and vegetables detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`
mc_sport^*	Enable sport related object detection for `MULTI_CLASS_BOX` and `MULTI_CLASS_BOX_ACCURATE` models	`true`, `false`

^* Dynamic parameter

Body Tracking parameters #

Namespace: body_tracking

common_stereo.yaml

Parameter	Description	Value
bt_enabled	True to enable Body Tracking	`true`, `false`
model	Detection model	string, ‘HUMAN_BODY_FAST’, ‘HUMAN_BODY_MEDIUM’, ‘HUMAN_BODY_ACCURATE’
body_format	Skeleton format	string, ‘BODY_18’,‘BODY_34’,‘BODY_38’,‘BODY_70’
allow_reduced_precision_inference	Allow inference to run at a lower precision to improve runtime and memory usage	`true`, `false`
max_range	Defines a upper depth range for detections [m]	double
body_kp_selection	Defines the body selection outputted by the sdk when retrieveBodies is called	string, ‘FULL’, ‘UPPER_BODY’
enable_body_fitting	Defines if the body fitting will be applied	`true`, `false`
enable_tracking	Defines if the object detection will track objects across images flow	`true`, `false`
prediction_timeout_s	During this time [sec], the skeleton will have OK state even if it is not detected. Set this parameter to 0 to disable SDK predictions	double
confidence_threshold^*	Minimum value of the detection confidence of skeleton key points	double, [0,99]
minimum_keypoints_threshold^*	Minimum number of skeleton key points to be detected for a valid skeleton	int

^* Dynamic parameter

Body Tracking parameters #

Namespace: body_tracking

common_stereo.yaml

Parameter	Description	Value
stream_enabled	Enable the streaming server when the camera is open	`true`, `false`
codec	Different encoding types for image streaming	string, ‘H264’, ‘H265’
port	Port used for streaming. Port must be an even number. Any odd number will be rejected.	int
bitrate	Streaming bitrate (in Kbits/s) used for streaming.	int, [1000 - 60000]
gop_size	The GOP size determines the maximum distance between IDR/I-frames. Very high GOP size will result in slightly more efficient compression, especially on static scenes. But latency will increase.	int, [max 256]
adaptative_bitrate	Bitrate will be adjusted depending the number of packet dropped during streaming. If activated, the bitrate can vary between [bitrate/4, bitrate].	`true`, `false`
chunk_size	Stream buffers are divided into X number of chunks where each chunk is chunk_size bytes long. You can lower chunk_size value if network generates a lot of packet lost: this will generates more chunk for a single image, but each chunk sent will be lighter to avoid inside-chunk corruption. Increasing this value can decrease latency.	int, [1024 - 65000]
target_framerate	Framerate for the streaming output. This framerate must be below or equal to the camera framerate. Allowed framerates are 15, 30, 60 or 100 if possible. Any other values will be discarded and camera FPS will be taken.	int

Debug parameters #

Namespace: debug

common_stereo.yaml

Parameter	Description	Value
sdk_verbose	Set the verbose level of the ZED SDK	int, `0` -> disable
debug_common	Enable general debug log outputs	`true`, `false`
debug_sim	Enable simulation debug log outputs	`true`, `false`
debug_video_depth	Enable video/depth debug log outputs	`true`, `false`
debug_camera_controls	Enable camera controls debug log outputs	`true`, `false`
debug_point_cloud	Enable point cloud debug log outputs	`true`, `false`
debug_positional_tracking	Enable positional tracking debug log outputs	`true`, `false`
debug_gnss	Enable GNSS fusion debug log outputs	`true`, `false`
debug_sensors	Enable sensors debug log outputs	`true`, `false`
debug_mapping	Enable mapping debug log outputs	`true`, `false`
debug_terrain_mapping	Enable terrain mapping debug log outputs	`true`, `false`
debug_object_detection	Enable object detection debug log outputs	`true`, `false`
debug_body_tracking	Enable body tracking debug log outputs	`true`, `false`
debug_roi	Enable region of interest debug log outputs	`true`, `false`
debug_streaming	Enable streaming debug log outputs	`true`, `false`
debug_advanced	Enable advanced debug log outputs	`true`, `false`

Dynamic parameters #

The ZED node lets you reconfigure many parameters dynamically during the execution of the node. All the dynamic parameters are indicated with a ^* in the list above and with the tag [DYNAMIC] in the comments of the YAML files.

You can set the parameters using the CLI command ros2 param set, e.g.:

$ ros2 param set /zed/zed_node depth.confidence 80

if the parameter is set successfully, you will get a confirmation message:

Set parameter successful

In the case you tried to set a parameter that’s not dynamically reconfigurable, or you specified an invalid value, you will get this type of error:

$ ros2 param set /zed/zed_node depth.confidence 150
Set parameter failed

and the ZED node will report a warning message explaining the error type:

1538556595.265117561: [zed.zed_node] [WARN]  The param 'depth.confidence' requires an INTEGER value in the range ]0,100]

You can also use the Configuration -> Dynamic Reconfigure plugin of the rqt tool to dynamically set parameters by using a graphic interface.

Transform frames #

The ZED ROS 2 wrapper broadcasts multiple coordinate frames that each provides information about the camera’s position and orientation. If needed, the reference frames can be changed in the launch file.

<camera_name>_camera_link is the current position and orientation of the ZED base center. It corresponds to the bottom central fixing hole.
<camera_name>_camera_center is the current position and orientation of ZED middle baseline, determined by visual odometry and the tracking module.
<camera_name>_right_camera is the position and orientation of the ZED’s right camera.
<camera_name>_right_camera_optical is the position and orientation of the ZED’s right camera optical frame.
<camera_name>_left_camera is the position and orientation of the ZED’s left camera.
<camera_name>_left_camera_optical is the position and orientation of the ZED’s left camera optical frame.
<camera_name>_imu_link is the origin of the inertial data frame (not available with ZED).
<camera_name>_mag_link is the origin of the magnetometer frame (ZED2/ZED2i only).
<camera_name>_baro_link is the origin of the barometer frame (ZED2/ZED2i only).
<camera_name>_temp_left_link is the origin of the left temperature frame (ZED2/ZED2i only).
<camera_name>_temp_right_link is the origin of the right temperature frame (ZED2/ZED2i only).

For RVIZ 2 compatibilty, the root frame map_frame is called map. The TF tree generated by the zed_wrapper reflects the standard descripted in REP105. The odometry frame is updated using only the “visual inertial odometry” information (loop closure is not applied). The map frame is updated using the Positional Tracking algorithm provided by the Stereolabs SDK, fusing the inertial information from the IMU sensor, and applying loop closure information.

map_frame (`map`)
└─odometry_frame (`odom`)
    └─camera_link (`<camera_name>_camera_link`)
      └─camera_frame (`<camera_name>_camera_center`)
        └─left_camera_frame (`<camera_name>_left_camera_frame`)
        | └─left_camera_optical_frame (`<camera_name>_left_camera_optical_frame`)
        | └─imu_frame (`<camera_name>_imu_link`)
        └─right_camera_frame (`<camera_name>_right_camera_frame`) 
          └─right_camera_optical_frame (`<camera_name>_right_camera_optical_frame`)

When the Geo Tracking module is enabled the ZED Node TF Tree reflects the following diagram:

Services #

The ZED node provides the following services:

~/reset_odometry: Resets the odometry values eliminating the drift due to the Visual Odometry algorithm. The new odometry value is set to the latest camera pose received from the tracking algorithm.
~/reset_pos_tracking: Restarts the Tracking algorithm setting the initial pose to the value available in the param server or to the latest pose set with the service set_pose.
~/set_pose: Restarts the Tracking algorithm setting the initial pose of the camera to the value passed as vector parameter -> [X, Y, Z, R, P, Y]
~/enable_obj_det: enable/disable object detection.
~/enable_body_trk: enable/disable body tracking.
~/enable_mapping: enable/disable spatial mapping.
~/enable_streaming: enable/disable a local streaming server.
~/start_svo_rec: Start recording an SVO file. If no filename is provided the default zed.svo is used. If no path is provided with the filename the default recording folder is ~/.ros/
~/stop_svo_rec: Stop an active SVO recording.
~/toggle_svo_pause: set/reset SVO playing pause. Note: Only available if general.svo_realtime is false and if an SVO as been chosen as input source.
~/set_roi: Set the Region of Interest to the described polygon.
~/reset_roi: Reset the Region of Interest to the full image frame.
~/toLL: converts from map coordinate frame to Latitude/Longitude Note: Only available if GNSS fusion is enabled
~/fromLL: converts from Latitude/Longitude to map coordinate frame Note: Only available if GNSS fusion is enabled

Services can be called using the rqt graphical tool by enabling the plugin Plugins -> Services -> Service caller.

It is possible to call a service also by using the CLI command $ ros2 service call.

For example to start Object Detection for the ZED2 camera:

$ ros2 service call /zed/zed_node/enable_obj_det std_srvs/srv/SetBool data:\ true\

and the service server will reply:

waiting for service to become available...
requester: making request: std_srvs.srv.SetBool_Request(data=True)

response:
std_srvs.srv.SetBool_Response(success=True, message='Object Detection started')

Assigning a GPU to a camera #

To improve performance, you can specify the gpu_id of the graphic card that will be used for the depth computation in the common_stereo.yaml configuration file. The default value (-1) will select the GPU with the highest number of CUDA cores. When using multiple ZEDs, you can assign each camera to a GPU to increase performance.