The system on my SE is quite different. A four-segment arc wrapping the rear of the car. Each segment has three alert settings which turn green, then amber, then red, as an obstacle gets closer, accompanied by beeping of increasing frequency. One the beep is continuous, STOP, for the love of all that's holy.
I reverse up to my garage doors to green or maybe amber, two central segments only. Red doesn't give me enough room to open the garage door. Once the door is open the warning segments vanish, but as I reverse in the two side segments quickly go red, sensing the sides of the doors. Once the rear of the car is inside, the right-hand segment clears but the left-hand one stays at red, warning me that the garage wall is that close. As I reverse towards the stack of plastic boxes at the back of the garage the central segments come on again, green then amber then red.
I can go just into the red segments and still have enough room behind the car to walk through to plug in the granny charger, and know the door will clear the nose of the car when I close it. If I get to the point where the beep is continuous, I know that clearance at the rear is uncomfortably tight to walk behind the car.
In conjunction with the excellent wing mirrors it works a treat. I would have killed to have had that on my Golf. I don't get on with these fish-eye cameras at all.