Light glow along a path and stairs following distance movement

Hi,

I am looking to illuminate a path to my house and up some stairs using a distance sensor to detect a persons position.

I have attached a sketch of what I am trying to achieve at various stages.

I wish to make 2 strips approx 5m long light up with a glow at the distance someone is detected along the path half a meter behind fading to off and half a meter in front of detection fading to off and follow the persons movements along the path until arrival at the stairs. Then 2m strips...

Light glow along a path and stairs following distance movement