Takeoff takes a really long time? Isaac sim running slow overall?

[andrewjong]

Want to debug this figure out what's going on.

[andrewjong]

John Keller:
I modified the omnigraph for our drone to print the (delta system time) / (delta physics time) to the screen. This shows how many times slower than real time the physics is. The "default" drone is the one we currently use in our sim, "no ascent" is our drone with the ascent sitl omnigraph nodes removed, and "no sensors" is our drone with the camera and lidar omnigraph nodes removed but still containing the ascent sitl node. "Blank world" just as a ground plane and a code, "Neighborhood" has houses and streets etc..., and "Construction" is a construction site with a lot of objects.

• Blank world
  • default: 2.1
  • no ascent: 1.8
  • no sensors: 1.0
• Neighborhood
  • default: 4.3
  • no ascent: 3.7
  • no sensors: 1.8
• Construction
  • default: 11.0
  • no ascent: 10.3
  • no sensors: 4.0
    Adding a second default drone to Construction gave 16 and a third drone gave 23. (In these tests the ascent node for the other two drones didn't initialize correctly because the domain_id and robot_name parameters need to be different and even though I changed them, they don't seem to actually get updated without saving and reopening the world. I didn't do this because it would take a long with the Construction world, but I think the results still show the issue.)
    It looks like the main things slowing down the physics are the sensors, the complexity of the environment and the number of drones. The ascent omnigraph node slows it down slightly, probably because running it in gdb is using one core, but I don't think its significant compared to the other factors. Also, the rendering fps is separate from the physics.

This is with a 3090 and a 12th Gen Intel(R) Core(TM) i7-12700K

Physics runs at 60 Hz by default. In Construction with one drone at 60 Hz, its 11x real time, at 10 Hz its 10.5x real time. If I increase it above 60 Hz it will start to get worse (80 Hz 14x, 100 Hz 20x) but it seems like values below 60 don't speed it up very much.
I tried playing with the different settings, like which solver it uses, enabling the gpu, etc.. but nothing had a significant impact.

[andrewjong]

Seems Isaac sensor rendering is the culprit. No good solution we can do on our end. Perhaps in the future we will switch to something more efficient.