The image you're showing is what I suggested. That said, Tesla has updated its visualization graphics once or twice in the last few months, and it's possible that these proximity displays have changed slightly with those updates. In any event, they occur both when parking and when driving, even at quite high speed, past nearby objects. Since reading your thread, I've noticed that on my car, even a curb can trigger them sometimes. They show up when driving down the highway in a lane that abuts a concrete barrier, too. When passing objects (parked cars, telephone poles, etc.), they'll "blip" for a second or two. FWIW, this is also covered in the
Model 3 Owner's Manual. Check pp. 58-59 (as marked with page numbers in the PDF). The image on p. 58 shows the display with proximity "arcs," and item 6 on p. 59 describes what those arcs are: