"Invisible" dog fences are Baked and WKTE;this takes the concept a little further, and will be particularly useful to those with wayward pets.
The device consists of a pair of lightweight goggles that the dog wears, connected to a backpack, which contains an image generation processor and a data library,
a battery, and a GPS unit.
The owner sets up one or more "geofences"; as the dog approaches the geofence, the system generates a virtual reality image of a very deep trench - like a haha - with a very high, blank wall on the other side. The image is sufficiently real that the dog will not proceed any further.
The DeLuxe version has an option to generate imaging such that the dog percieves itself to be between very high fences, which route it back to the owner's location, controlled by an app on their cellular phone handset. They can also pick up the view from a webcam on the pet's collar.
It is a relatively simple task for the owner to set up "safety" fences along the kerbs of all the roads in their home area.
A version for cats is being developed which works in the same way, except that on a coded command sent by the Borg Collective the cat hears (and sees) a pack of slavering dogs pursuing it, and busy major highways appear as nothing more than an area of open parkland ...