Visual cues in a full 3D game to help the player to identify the location of each object

Question

I am working on adding some visual cues to the player to help identify where each objects are in 3D. In many space games, there is usually an indicate on the edge of screen that reflects the direction towards that particular object. For example, an indicator in the upper middle edge of screen may indicate that particular object is straight ahead and an indicator in the lower middle of edge screen may indicate that object is directly behind.

If the game is mostly 2D, such as most FPS shooters, this would not be a difficult problem. Then the indicator is basically a top down radar. But with full 3D, Im unsure how to translate this inherently 3D information to 2D in a intuitive, yet meaningful way. If just using the 2D radar method, then I cant convey pitch/elevation information. For example, an indicator in the upper middle edge of screen can not differentiate between an object that is straight head in the same plane as the player versus something that the player needs to tilt 45 degrees upwards to see.

Is there something better than the top down radar method?

Answer 1

If we consider a 'classic' top-down view minimap, we can consider that the minimap is at the plane of z = 0.

To help show the 3d dimension, you could add an additional plane at x = 0 and another at y = 0, and project a line between the object and the 3 planes.

Of course, you'll have to modify the angle of view of the 3d map with regard to the current view of the

Another thing you could try is have the map around the 'ship' in the environment and have have the objects in space project a line down (or up) on that map: this gives an idea where the other objects are relatively to the 'ship'.

Eve Online does this and it gives a nice feeling. In the following screenshot, we can see that the space station is at a bit more than 10 km, with the player's ship is in the centre of the concentric circles.