Huge backdrop/skybox help.

I am making an opening scene which involves a view of the city I am making. The scene has the player on a train approaching the city, then entering it. The problem is, my city is HUGE and oddly shaped, so I wanted to see if there was a way to reduce polygon counts by using a skybox effect.

This is the layout:

Its bad, but you can kinda see what I am doing.

All help is appreciated.

Can’t give you advice without more information or photos. How much of the city does the character interact with? There shouldn’t really be a reason why you couldn’t use the same 3d skybox as detail while the character is outside as in unless they have access to the entire thing.

More information about what you intend to do and what you already have in place would be very helpful.

If I understand what you want correctly then a 3d skybox would work

A train with the player on it travels inside the first wall of the city (as he escapes), you do not see inside the city, im going to have a loading screen beforehand. I just want the player to be able to see all the visible walls of the city, the citadel, and the tops of the rooftops as the train rolls in. Don’t mind the trains height (Its a monorail) so everything can be fit in, HAMMER just wont let me build a city that large without surpassing all of the limits.

Stick the train in a separate, sealed-off part of the map shaped like a long corridor, which is the path it takes. Make a copy of the city and scale it to 1/16th and delete the areas which aren’t visible from any point along the train’s path. Make this your 3D skybox and project it so that you can see it from inside your corridor. When the player gets to the stop, teleport them to an identical traincar in the real city, so the transition is seamless.

(aka do what Valve did in the opening part of Portal 2, listen to the commentary for details)