well, that means you want it to be high quality, not just a textured plane. so i would suggest 1 of 2 things:
1. use a textured plain for each star/star cluster/solar system that you want to show. rotate each plane to face the camera.
Pros:
-easier to do(less media required)
-uses less polys than other methods
Cons:
-some things will look very flat
2. use very small spheres for stars/star clusters and planes for much smaller groups of objects. add a shader or set object light 0 for the spheres to make them look very bright. rotate all planes that you use to face the camera.
Pros:
-looks much better
-shaders will sometimes react better on the non-plane objects
Cons:
-uses a lot more polys than other methods
-uses more media(textures for more objects than just planes; and possibly custom shaped objects besides spheres and planes)
hope that helps. also, to make it look more like a hologram, you could have it expand from a central point when it's activated(like in Star Wars), or use planes to make static lines go through the hologram every few seconds(im not sure exactly what those lines are called
)
