This example demonstrates how to use ROS 2 Composition to convert the ZED Depth map messages into a virtual laser scan by using the depthimage_to_laserscan package.
Usage:
ros2 launch zed_depth_to_laserscan zed_depth_to_laserscan.launch.py camera_model:=<camera_model>the launch file will start the ZED Wrapper node, the Depth Image to Laser Scan converter node, RVIZ2 for data visualization, and a Robot State Publisher node to broadcast the ZED camera static frames.
You can disable RVIZ2 by using the launch argument rviz:=false.
You can also get the list of all the available launch parameters with
ros2 launch zed_to_laser_scan zed_to_laser_scan.launch.py -s
The launch file creates a ROS 2 container to run the two components:
# ROS 2 Component Container
container = ComposableNodeContainer(
name='zed_depth_to_laserscan',
namespace=camera_name_val,
package='rclcpp_components',
executable='component_container',
composable_node_descriptions=[
zed_wrapper_component,
zed_cvt_component
],
output='screen',
)The zed_wrapper_component variable defines the ZED node:
# ZED Wrapper component
zed_wrapper_component = ComposableNode(
package='zed_components',
namespace=camera_name_val,
plugin='stereolabs::ZedCamera',
name=zed_node_name,
parameters=[
# YAML files
config_common_path, # Common parameters
config_camera_path, # Camera related parameters
# Overriding
{
'general.camera_name': camera_name_val,
'general.camera_model': camera_model_val,
'svo.svo_path': svo_path,
'general.serial_number': serial_number
}
],
extra_arguments=[{'use_intra_process_comms': True}]
)the parameters are loaded from the YAML files defined by the variables config_common_path and config_camera_path. Note that camera_name, camera_model, svo_file, and serial_number are overridden by the launch options, so their values in the YAML files are ignored.
The zed_cvt_component variable defines the "Depth Image to Laser Scan" node:
# Depth to Laser scan component
zed_cvt_component = ComposableNode(
package='depthimage_to_laserscan',
namespace=camera_name_val,
plugin='depthimage_to_laserscan::DepthImageToLaserScanROS',
name='depthimage_to_laserscan',
parameters=[
config_path_cvt,
# Overriding
{
'output_frame': camera_depth_frame
}],
remappings=[
('depth', zed_node_name_val + '/depth/depth_registered'),
('depth_camera_info', zed_node_name_val + '/depth/camera_info')
],
#extra_arguments=[{'use_intra_process_comms': True}] # Uncomment when supported by the package
)the parameters are loaded from the YAML files defined by the variable config_path_cvt. The parameter output_frame is overridden by the value of the variable camera_depth_frame initialized above to match the name of the link broadcasted by the ZED node: camera_depth_frame = camera_name_val + '_left_camera_frame'.
The topic names depth and depth_camera_info are remapped to match the topic names published by the ZED node.
Unfortunately, we cannot leverage the Intraprocess Communication behavior and improve data transmission performance with zero-copy because the default QoS setting of the depthimage_to_laserscan::DepthImageToLaserScanROS component is not compatible [see issue]. If this will be fixed in the future you can uncomment the line #extra_arguments=[{'use_intra_process_comms': True}] # Uncomment when supported by the package.