Zombie spawn range

Hey guys, I have been playing dayz for ages, but never figured how zombies spawn. I.e. I am interested if they spawn if a player is <350 m ( official) to the zombie location or the town location? E.g. I am at one side of Novodmitrivsk seeing zombie at the opposite side, which is ~500 m away from me. Does it mean there is another player or is that from me, since I am 50m away from Novo.