This is the method used to route pcbs when digital (noisy) and analog (hopefully not noisy) ground planes need to be kept separated.
In order for the circuit to work electrically, the grounds must be at the same potential, but to prevent the noisy digital currents from flowing along the analog ground plane, the intertie can only happen in just one place
This is the single point grounding principle. If you do not understand this principle, you have no business designing mixed signal analog-digital systems.