Using anywhere from four to 12 piezoelectric sensors that are glued to the backsides of body panels or hooked into existing electronic infrastructure like Park Distance Control, Hella calls it "a sense of touch... for the whole outer shell." An algorithm processes the electric signal from pressure on the "structure-borne noise" on the body panel, and the company says that algorithm can figure out "where the scratch is and how intensive it is," or if it's come from something like hail or a falling tree. It's designed to work on any of the materials you'd find in modern body panels, from steel and aluminum to carbon fiber and thermoplastic.
If the IDDS is wired into the car's GPS or a telematics system like OnStar, it can record the details of when the damage happened, and if plugged into a car's numerous cameras it might be able to snap a picture of the offender. You – and the offender and your insurance company – would then have real-time information on what, where, when, and how the damage occurred. Hella wants to have the system on production cars by 2018, and it can't come a day too soon; those offside scratches while you were away may never have to haunt you again, and mall parking lots will never be the same.