Isaac Sim 2022.2.0 Unable to add second ROS2 camera

I need to model an Intel Realsense camera for use with ROS2, and I’ve made several attempts today to build the ActionGraph from scratch which have all failed. I’m attaching the results from two attempts, including log output.

The first (01_realsense.usd) manages to open the two viewports (1 and 2) with the correct camera output, but the ROS2 topics are not getting published and I see errors in the terminal. Please note that everything was working correctly when I had only the left camera elements in the ActionGraph; the topics were published. It’s when I added the right camera elements that things went wrong. Here is the error output, note it is similar that reported in
ROS2 point cloud publisher is not working:

[WARN] [1673558664.762561150] [rclcpp]: logging was initialized more than once
2023-01-12 21:24:24 [242,023ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7f89b4e2c9d0>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_2'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_2_NodeWriterWriter'
2023-01-12 21:24:24 [242,023ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7f89b4e2cdd0>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_2'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_2_NodeWriterWriter'
2023-01-12 21:24:24 [242,023ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7f89b4e15250>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1_NodeWriterWriter_01'
2023-01-12 21:24:24 [242,023ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7f89b4e15650>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1_NodeWriterWriter_01'

The second (02_realsense.usd) is another attempt I made, this one crashes when opening. See the long error log attached.

01_log.txt (1.8 KB)
01_realsense.usd (1.1 MB)
02_log.txt (46.3 KB)
02_realsense.usd (1.1 MB)

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OK, here’s something interesting. I managed to get just one ROS2 camera working, see the realsense_good.usd attached to this post.

Then I simply ran the simulation, stopped it, and saved the file to realsense_bad.usd. No change to the model whatsoever. If I open realsense_bad.usd, the ROS2 topics do not get sent and I have the following error in terminal:

[WARN] [1673618006.011342929] [rclcpp]: logging was initialized more than once
2023-01-13 13:53:26 [43,323ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7fa852d30850>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1_NodeWriterWriter_01'
2023-01-13 13:53:26 [43,323ms] [Error] [omni.isaac.core_nodes.impl.extension] Could not process writer attach request (True, <omni.replicator.core.scripts.writers.NodeWriter object at 0x7fa852d30c50>, '/Render/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1'), Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_omni_kit_widget_viewport_ViewportTexture_1_NodeWriterWriter_01'

realsense_bad.usd (1.1 MB)
realsense_good.usd (1.1 MB)

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We are also experiencing similar issues, did you find a solution?

I wouldn’t call it a solution, but our current workaround is to take the entire Carter_ROS model, save it as flattened, and then remove all the elements other than the cameras. You’re left with a stereo camera that works properly (so far).

Another trick that helps is to change the viewport IDs from 0,1 to 1,2, so that you don’t lose control of your original viewport (0) when the simulation starts. Oh, and NEVER save the model after running it (playing the simulation). If you need to make changes, restart Isaac Sim and load a fresh copy of the model which has never run, make your change, then save it.

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Thanks for the detailed explanation.

We have a few fixes for this issue in 2022.2.1, releasing soon:

  • you can now change parameters on the camera helper node and pressing stop/play will update any settings that were changed.
  • the issue with saving and reloading should be fixed. In 2022.2.0 you will notice an extra /Render prim get created on save (usually visible in the layer tab). deleting the render product under that prim will also solve that error.
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