Could not process writer attach request...OmniGraphError: Tried to create a node in a path without a graph

Robotics & Edge Computing Robotics - Isaac Isaac ROS
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I am trying to use a Nova_Carter_ROS sample robot in my scene. Every time I start the simulation there are multiple errors showing up on the terminal and none of the RTX Lidar data will work over ROS2 but the IMU and other topics are publishing:

2024-10-12 22:47:25 [294,501ms] [Error] [omni.isaac.core_nodes.impl.base_writer_node] Could not process writer attach request (<omni.replicator.core.scripts.writers.NodeWriter object at 0x7fe7bc73e140>, '/Render/RenderProduct_Replicator_02'), OmniGraphError: Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_Replicator_02_NodeWriterWriter'
2024-10-12 22:47:25 [294,501ms] [Error] [omni.isaac.core_nodes.impl.base_writer_node] Could not process writer attach request (<omni.replicator.core.scripts.writers.NodeWriter object at 0x7fe7bc73f1c0>, '/Render/RenderProduct_Replicator'), OmniGraphError: Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_Replicator_NodeWriterWriter'
2024-10-12 22:47:25 [294,501ms] [Error] [omni.isaac.core_nodes.impl.base_writer_node] Could not process writer attach request (<omni.replicator.core.scripts.writers.NodeWriter object at 0x7fe7bc73f460>, '/Render/RenderProduct_Replicator_01'), OmniGraphError: Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_Replicator_01_NodeWriterWriter'
2024-10-12 22:47:25 [294,501ms] [Error] [omni.isaac.core_nodes.impl.base_writer_node] Could not process writer attach request (<omni.replicator.core.scripts.writers.NodeWriter object at 0x7fe7bc73f6d0>, '/Render/RenderProduct_Replicator'), OmniGraphError: Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_Replicator_NodeWriterWriter'
2024-10-12 22:47:25 [294,501ms] [Error] [omni.isaac.core_nodes.impl.base_writer_node] Could not process writer attach request (<omni.replicator.core.scripts.writers.NodeWriter object at 0x7fe7bc73f700>, '/Render/RenderProduct_Replicator_01'), OmniGraphError: Tried to create a node in a path without a graph - '/Render/PostProcess/SDGPipeline/RenderProduct_Replicator_01_NodeWriterWriter'

Steps to reproduce:

  1. Start IsaacSim v4.1 or v4.2 with the ROS2 bridge enabled
  2. Drop a Nova_Carter_ROS sample robot into the scene
  3. Start the simulation
  4. Observe the crash log in the terminal window and see that no lidar related data is publishing as a ROS2 topic while the imu and odom data is publishing normally

I tried to include the USD file I’m using for the scene but it says that file type is not allowed.

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Solution It appears as though an extra “Render” layer can get saved in the layer stack when you run the simulation and then save the changes to the USD after running it. To fix this issue, delete the “Render” layer in the Layer stack and it should work the next time you run the simulation.

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