There's already precedent about this involving radiated IR, which ruled that police may not use such tools without a warrant, as it violates what people normall

There's already precedent about this involving radiated IR, which ruled that police may not use such tools without a warrant, as it violates what people normally consider to be private information. It's possible that different rulings will come in the future, but you have people defending drug dealers to thank for essentially ruling that this requires a warrant at present.