Really?
I still have (somewhere… :person_facepalming: ) a few ultrasonic rangefinders, and they were surprisingly accurate, at least at big objects. Indoors, they were accurate to a fraction of an inch.
I could ping the opposite wall, and with a slight change in “aim”, ping a cabinet or wall-unit, and it’d reflect the shorter distance.
I mainly used them just to play with, but I was hella impressed how accurate they are, especially hearing the faint click-click-click as it’d calculate the distance after locking on.
Was also fun to confuse it by slowly waving it closer/nearer/closer/nearer/… and hear it clicking away but not getting any consistent reading to lock onto. Almost felt bad for the critter. 