Agents of Discovery players will find your GPS-based Challenges by using the GPS services on their mobile device. Challenges will unlock within a set proximity to the player. You can customize the Reveal Radius (previously known as the Scan Radius) by going to the My Missions page and clicking “Edit Map” for the chosen Mission.
If you have a small Mission, you may want to make your Reveal Radius smaller so players have to explore your entire Mission area to unlock all the Challenges. If you have a larger Mission, you may want to make the Reveal Radius larger so it is easier for players to find your Challenges. The Reveal Radius only applies to GPS or Mixed Missions.