Added point_cloud_transport

[ahcorde]

We started to port point_cloud_transport from ROS 1 to ROS 2. This issue track the progress ros-perception/point_cloud_transport#1

I will open this PR as a draft because the package is not released yet, we need to discuss it makes or not to include this dependency.

It helps me a lot to debug issue in the point_cloud_transport.

[john-maidbot]

These helpers seem useful to other users, not just rviz. Should we move these helpers inside pointcloud transport (they might already exist)? I can make a PR for that if you agree

[ahcorde]

This might add some knowledge about the point cloud plugins that are installed. I prefer to keep point_cloud_transport agnostic

[john-maidbot]

Since this function is already explicitly a specialized sensor_msgs::msg::Poincloud2 class, does it need to be a template?

[ahcorde]

The ImageTransportDisplay class has the same structure. I would like to keep it the same for consistency.

[FranzAlbers]

Thanks for working on point_cloud_transport and the rviz2 plugin, @ahcorde!

I've noted that it's currently not possible to subscribe to two Draco compressed point clouds at the same time.
RViz2 crashes when two topics ending with /draco are subscribed with Pointcloud2 displays:

terminate called after throwing an instance of 'rclcpp::exceptions::ParameterAlreadyDeclaredException'
  what():  parameter 'SkipDequantizationPOSITION' has already been declared
Aborted

The topics don't even need to be published, just typing in the second /draco topic in the topic field lets RViz2 crash.

[ahcorde]

I recently added this commit ros-perception/point_cloud_transport_plugins@45c42b0 fixing the parameter names which was backported to iron and humble.

can you check if you are using these changes too ?

[FranzAlbers]

Sorry for the late reply, I had some days off.
I am already using that commit, but the crash occurs nevertheless.

It seems like SkipDequantizationPOSITION and the other SkipDequantization parameters are declared in draco_subscriber.cpp, which was not touched by that commit.
Currently, there is only one parameter SkipDequantizationPOSITION parameter for all Draco subscribers in rviz2. If a second Draco subscriber is initialized, the same parameter is declared again, and rviz2 crashes.

The crash does not occur if I comment the content of the DracoSubscriber::declareParameters() function, but in this case, these parameters cannot be changed at all.

[sinamoghimi73]

Hello, I'm trying to visualize the point cloud published by point_cloud_transport::Publisher. I get the data with ros2 topic echo ... but when trying to load in rviz2 I get the following warning:
requesting incompatible QoS. No messages will be sent to it. Last incompatible policy: RELIABILITY_QOS_POLICY

and nothing appears in rviz2. I would be grateful if you could guide me.

[ahcorde]

Hello, I'm trying to visualize the point cloud published by point_cloud_transport::Publisher. I get the data with ros2 topic echo ... but when trying to load in rviz2 I get the following warning: requesting incompatible QoS. No messages will be sent to it. Last incompatible policy: RELIABILITY_QOS_POLICY

and nothing appears in rviz2. I would be grateful if you could guide me.

@sinamoghimi73 you should be able to change the QoS, check the following image:

[adityapande-1995]

Changes look good to me, will try this out locally once, and then approve !

[ahcorde]

friendly ping @adityapande-1995

[adityapande-1995]

🚀

[ahcorde]

• Linux
• Linux-aarch64
• Windows

[ahcorde]

this PR ros-perception/point_cloud_transport#64 on point_cloud_transport should fix the issue on the Windows CI

[ahcorde]

• Windows

[ahcorde]

• Linux
• Linux-aarch64
• Windows