Low real time factor and sky rendering issue

[lijianwen1997]

Describe the bug
I cloned the latest VRX repo and ran the simultor with default settings. However, the real time factor was very low (38%). If I increase the step size to 0.05, it can increase to 78% but I don't think it is the right way to solve the problem. Plus the sky is not rendered properly. I tried both nvidia-driver-470 and nvidia-driver-530 but it did not help. It will be great if you can let me know how to increase the real time rate and fix the rendering issue.

To Reproduce

1. Run ros2 launch vrx_gz competition.launch.py

System Configuration:

• OS: Ubuntu 22.04
• ROS Version: ROS 2, Humble
• Gazebo Version: Gazebo Sim 7.5.0
• Graphics Card: Nvidia RTX 2080
• GPU Driver: nvidia-driver-530 / nvidia-driver-470
• CPU: i7-8700
• Memory: 32 GB (only 30% is used when VRX is running)
• VRX

Screenshots

Additional notes
We also reproduced this low RTF and redenring issue on a Laptop with i7-8565 CPU and UHD 620 GPU.

[M1chaelM]

We usually see these symptoms when the system is unable to access the GPU (so it makes sense that you would see this on the laptop). Are you using Docker or running directly on hardware?

Assuming you are running directly on hardware:

• If you could try driver version 470 for now that would be helpful for troubleshooting.
• What is the output of nvidia-smi?

[lijianwen1997]

Thanks very much for your help!
I am running directly on hardware. I changed the driver to 470 but it did not fix the issues. The output of nvidia-smi when vrx is running is as below:

What's more, I saw ruby 3.0 has been stopped unexpectedly. Not sure if that caused the issues.

[lijianwen1997]

https://gazebosim.org/docs/garden/troubleshooting#prime-select-command-line-tool

I visited gazebo troubleshoot page and configured Gazebo to always use Nvidia and it fixed the sky rendering issue! The RTF increased to 60%.

Please let me know if you have any suggestions to increase the RTF.

[caguero]

@tejalbarnwal was kind enough to test a few things:

• Confirm that commenting the cameras and laser of the WAM-V restores RTF to 100%.

https://github.com/osrf/vrx/blob/main/vrx_urdf/wamv_gazebo/urdf/wamv_gazebo.urdf.xacro#L162-L166

• Try out a simplified version of the WAM-V ideally with just a single link (no joints) and the minimum amount of plugins. Maybe just one buoyancy plugin and one hydrodynamics plugin. See if this makes any difference.

[tejalbarnwal]

Hey,
I tested out disabling the 3D lidar and the camera sensors, and I found the following outcomes:

Test Condition	RTF
With Lidar and Cameras	0.82
Without Lidar	approximately 0.82
Without cameras and disabled Lidar visualization	0.95
Without cameras and enabled Lidar visualization	fluctuating between 0.82 and 0.96(average around 0.89)
Without cameras and Lidar	0.995

It appears that the cameras may be the primary cause of the reduced RTF. I plan to assess a basic URDF with minimal joints and plugins later tonight.