The radar is located in the upper-right corner of the screen. Its position can vary depending on whether you have a panel open and if you have enabled the stretch UI option. The Radar displays your heading, your field of view, and information about objects around you in the form of colored dots:

If the color of a dot is slightly dimmed, that indicated that the object in question is above or below you.

In addition to the dots white, pink and red dots will show up as a hollow square instead if the player is in your allegiance. Hostile players will show up as an X if you are also a player killer and they are not in your allegiance.