Where do the odom topics come from?

[Combuster54]

Hi,

I would like to ask where can I find where those types of odoms comes.

/odom
/odom/ground_truth
/odom/local
/odom/raw

I see that ground_truth is inside gazebo.xacro, but I couldn't able to find the where the others come from.
Can someone help me?

[wk1215]

我也想知道这个问题；以及我在测试的时候,同样的运动指令发现gazebo移动和rviz显示的差异较大?这个如何解决?