How to set frame_id for Rviz?

[ktnguyen2]

In [https://github.com/NVIDIA-AI-IOT/redtail/wiki/Testing-in-Simulator#rviz-visualization](the wiki), it was mentioned to set 'frame_id' accordingly. How do you know what to set 'frame_id' to?

I am trying to use the redtail_debug node in Rviz with only the caffe_ros node and gscam node, and I am having trouble visualizing the pose. Under camera topic, I get that the camera frame does not exist.