I created window with 4 ViewportWidgets each streaming a camera from the scene.
Even though I provide an exact prim path to the camera that I want the viewport to, it randomly shows other cameras, and then sometimes even crashes Isaac Sim.
Strangely, it seems the viewports stabilize if your mouse cursor is over one of the viewport widgets.
I don’t understand why mousing over the camera would have any effect on which camera is rendered, or the performance.
Thank you for reporting this issue with the ViewportWidget streams in Isaac Sim. It appears you’re experiencing some instability and unexpected behavior with camera rendering in multiple viewports.
I would strongly recommend upgrading to the latest version of Isaac Sim, which is currently version 4.2.0.
upgrading to the latest version of Isaac Sim, which is currently version 4.2.0
Yes, I would like to use the latest version. I tried to upgrade and had other problem so reverted back to 4.0.0 until the installation and libraries issues are resolved.
Given this thread implied a bug or issue with Isaac Sim and there hasn’t been more activity from other users confirming or reproducing I guess very few other people are using this feature.
Anyways, I wanted to provide an update in case this gets looked at in the next version of Isaac Sim.
I can confirm this viewport instability issues still persists on Isaac 4.2.
Here is another small animation. (Perhaps not having to click to watch video will increase likelihood of others understanding the issue)
You can see the cameras start as expected, then as the mouse moves off window the cameras rotate streams randomly or even go blank. It would be bad if cameras did not work, but the fact that they can provide the wrong stream to the different camera input is what was most alarming since it could mislead users.
Also, I don’t understand why this would be related to mouse movement. There is likely some optimization which assumes the mouse off window means it can reduce computation requirements and there is mismanagement of memory pointers.
Mitigation
I have also confirmed there is a workaround if others depend on this feature.
If you right click the header and select “Move to External Window” and move your mouse out fast enough the issue does NOT occur. Meaning even when mouse is off the window, the cameras remain stable which is what the behavior should always be.
This likely confirms that external windows use different set of behaviors and management which prevents the issue.
