I imported a google heighmap of North America 50% to scale. Was awesome. Performance was a little painful. Now, as soon as i added anything other then the landscape, full meltdown. lol… checkerboard landscape worked fine tho.
255x255 is a bit much, unless you want something like 5,000 players on your map.
You are effectivly making a 160 mile x 160 mile map. average walk @ 3mph. looking about 53 hours to walk from one side to the other. about 2.5 days … roughly.
Wont happen. We can say “oh yeah, well, you can do it”. In all serious talk here, you can, but dont. You will struggle with optimizations for the next … well, whens the 2k nvidia series come out? lol
you can use lots of culling and this and that, but, in the end, like i said, 2.5 days to walk across it and unless you have like 5k users per map (and you wont) then your just making big for the sake of “wouldnt it be neat if…”.
Who am i to say not to tho, feel free. Its your vision, im just letting you know (in measurable terms) the size you are looking to create.