OK,this is what do and I`m sure it`s the best way to get pretty accurate height data from GE into BTB in the shortest time.This method requires 3D Route Builder installed.First thing you have to do is making a path in GE, but
don`t join up start and end points,make sure and leave a gap between these two points which should be equal to the node spacing.Save the path as KML file.Next go to
http://www.gpsvisualizer.com/elevation and in the
Upload a file box insert your saved KML file from GE.Then choose
Output format(choose
GPX) and click
Convert & add elevation button.Save it and rename the file to
yourtrackname.gpx ,for example
LagunaSeca.gpx if you make this track.That`s it,you`ve got elevation data of your track, but obviously they aren`t very accurate,because I`ve seen many times wrong height data from GE like from
15-20 or even higher feet spikes in the track itself,not accurate at all,right?That`s why we need a program like 3D Route Builder to get better,more accurate elevation data and smooth them as well.In 3D Route Builder click
FILE\OPEN ROUTE and load your
GPX file which you got from
GPS VISUALIZER site.When you see the elevation data with an altimeter line showing in the program press
Ctrl+A and select in blue all the columns.Next go to
ROUTE\ALTITUDE\UPDATE FROM GEO TOOL and see how the program updates the altitude of gpx extracting better,more accurate elevation data.Next in the same menu go to
SMOOTHING and mess around with
POINT AVERAGING settings.To check out the
SMOOTHING amount just zoom in close to the track.When the program finishes the
SMOOTHING processing click
FILE\EXPORT and save it as
GPX file and then
EXPORT again,but this time as
KML file.Open BTB and go to
FILE\IMPORT\GOOGLE EARTH and load your
GPX file exported from 3D Route Builder.While importing make sure that
OPEN ENDED(POINT TO POINT) in
TRACK TYPE section is checked and that
ALL in
SAMPLING one is checked either ! Don`t worry when you choose
OPEN ENDED,you can easily join these two points up in BTB and make it as the START/FINISH line.
Apart from laser scanning,which is obviously super accurate and the best method of obtaining all kind of data like elevations,coordinates,dimensions of buildings on the track and so on this is the best way of getting pretty accurate GPS data from GE into BTB comparing to other standard "home"methods and doesn`t require the hell of a work.I use this method and I`m really happy with the end results.How to get really accurate data of terrain I use completely different procedure.By the way I use BTB only for a rough layout and terrain and then I import it into 3ds Max and then I start fine tuning a track and terrain mesh by editing polys,UVW mapping,shaders and so on.There`s no way you can get a fantastic-looking track with photo realistic materials ,textures and shaders using just BTB.The reason why so many people uses BTB instead of 3ds Max while building tracks is only one it`s very easy to use,but let`s face it there`s nothing like 3ds Max where you can use different track modelling techniques like lofting(BTB uses technique very similar to lofting in 3ds Max,not exactly the same,but similar and a way much easier to use ),FFB Box modelling etc.Besides, if you have got gMotor2 Tool plugins installed in 3ds Max it`s a lot quicker and easier to make a track and modelling buildings in 3ds Max is such a fun,the hardest part is always finding hi res photo reference material. The difference between a great-looking track and one which looks like crap is very often skin deep.
I hope it helps.