Recentering the Nav

I can't find any documentation on this, but it looks like green is moving traffic and red is not-so-moving traffic. I haven't figured out what the ridges mean.

 

that's what I thought.
the ridges must have some meaning

 

I think that the recenter button may only appear when you are in navigation mode not when you are in map mode. The home button works in both cases. This is on the 11" display, no idea about other displays. I haven't checked recently though but I am pretty sure that when I was navigating with the system, there was a recenter button on the bottom after my wife was trying to look at something on the screen (she likes to see if the navigation will tell her what body of water we just passed).