Remember there is a built-in orb locator for all agents in Crackdown 2. All you do is push UP on the D-Pad.

If you want a really good view of where the Orbs are, pause the game. Then unpause the game and immediately push UP on the D-Pad.

The onscreen map briefly has a very nice aerial view when coming back from the pause screen so the Orb detector will pick up more locations.