@ asasinuxp
I looked a little deeper to BTB & other apps (3D Route & GE), I was wrong, I'm sorry....all bulls***
So, what I would do :
1.) Create your route with GE (using the newest one, version 6) & save it as kml. (< 500 pts limitation export => so create more routes if needed to glue them after)
2.) Load it in 3D Route Builder, select all & update Altitude from Geo Tool
3.) Check the new update in GE (automatically done)
4.) Export as CSV after been filtered & keep just the 3 variables => altitude, longitude & latitude
5.) Import in BTB as CSV file with sampling on to 2 -10 if routes points are real close to each other + data to 'Long, Lat & Height'
6.) Eventually, activate 'Ignore 1st line' if not manually edited. Check Brendon CSV example.
7.) Roughly re-adjust the street points (Node/Control Points), so you get a nice interpolated street. => pay more attention in turns. => Try to keep distance evenly.
8.) Once you've been thru all 25 km (would be maybe 3 Routes 'merged' together 'manually' in CSV file) curves, export the street only.
9.) Export as X file
10.) Load it in your favorite app or 3DsimEd
10a.) If you don't have any X importer, load 3DsimED
10b.) Rename eventually the material & mesh
10c.) Explode the whole prior to export as DAE/3DS, best is DAE (standard in industry)
10d.) Export
10e.) Load that file in your 3D app (check for plugins => importer/exporter if not existing)
11.) Select all polys & merge the vertices together since X files splits each poly with its material.
12.) Now the magical part, in tight curves, introduce with your 3D tools more edges to get a real nice interpolation. Prior to that, 'quadrangulate' (Maya talk) the mesh to ease your work.
13.) Iterate thru all curves/turns that needs some more polys & repeat the technique. UV's will be fine since you tinkering inside the mesh.
Done !
For sure, I've tested it even further, so from my BTB terrain (Left/Right merged), you can then work from there & attach anything to it, as I suggested it to you, maybe a 'baked' outside terrain which aligns till your skydome.
Another cool thing, since I haven't figured with all my programs here, how to exactly extract a real terrain & bake it to polys, you could create another Route which 'contours' your map size (something like a curve network but with GE Routes) & afterward loft/birail the border edges....
I hope you understand somehow what I mean.
All this was 'successfully' tested today & thx to you really...
Enjoy guys !!!
P.S: I found 1 tutorial to extract/convert real terrain into HM/Relief Maps (
http://www.massgate.net/read.php?77960,111959,171840) & it even works !! Wow....