ros_ign_bridge error for nest model sensor topic

[gezp]

I create a nest model sdf which contains a camera sensor with default topic, then i publish this topic to ros by using use ros_ign_bridge.but i get a error like this.so how to solve it? i have no idea now, thank you.

what():  Invalid topic name: topic name must not contain characters other than alphanumerics, '_', '~', '{', or '}':

this is topic info i use ign topic -l to get

/world/demo/model/my_robot/link/front_camera::camera/sensor/camera/image

[chapulina]

Nested models aren't fully supported in Ignition yet, see this PR in the works: gazebosim/gz-sim#258

Do you have simple world / launch files that reproduce your issue?

Also, what Ignition / ROS versions are you using?

[gezp]

I use ros2 foxy and ignition dome. now i know the reason of the error, because the characters "::" is valid in topic name for Ignition-transport ,but is invalid for ROS .i solved this by modifying the source code of ros_ign/ros_ign_bridge ros2 branch.

First, I copy replace_delimiter() function in convert.cpp to parameter_bridge.cpp, which is used to replace :: with / so that make topic name of ros valid. Then, I modify the case FROM_IGN_TO_ROS in main(). (i only change parameter_bridge.cpp)

Before:

        case FROM_IGN_TO_ROS:
          ign_to_ros_handles.push_back(
              ros_ign_bridge::create_bridge_from_ign_to_ros(
                ign_node, ros_node,
                ign_type_name, topic_name, queue_size,
                ros_type_name, topic_name, queue_size));
          break;

After:

        case FROM_IGN_TO_ROS:
          ign_to_ros_handles.push_back(
              ros_ign_bridge::create_bridge_from_ign_to_ros(
                ign_node, ros_node,
                ign_type_name, topic_name, queue_size,
                ros_type_name,replace_delimiter(topic_name, "::", "/"), queue_size));
          break;

[chapulina]

@gezp , do you have a minimal example of a world that results in topics with :: in them?

I think that ideally we should be substituting the :: for / from topics at the ign-gazebo level.