by toprob » Fri Apr 27, 2007 10:06 am
FSX default mesh for NZ is based on SRTM 90 metre data, which for use in FS2004 was resampled to 76 metres. I assume the same applies for FSX. That's why to get the full effect of the default mesh you set your mesh to 76 metres.
Trying to increase the resolution by resampling is basically making up the intermediate detail, so really you are looking at a 90 metre resolution.
SRTM data for around Milford is damaged -- hence the huge rounded mountains, which I've always imagined are scans of clouds. Incidentally, you can fix the elevation to some degree by using a non-SRTM mesh such as Christian's, but the topo data (rivers etc) is kind of locked to the damaged data, so it will still display funny.
Christian's freeware 75 metre mesh is not based on SRTM data, so it doesn't have the messed-up Milford, and it is also resampled from much higher resolution data -- the same data which produced the 20 metre mesh (I assume) so it is inherently more accurate.
That's why Christian's freeware mesh will display better in FSX -- although since there are changes to the way mesh is created in FSX, it may or may not perform as well. What we really need is a 75 metre mesh recompiled for native FSX. However I don't notice any real performance hit from his 20 metre mesh in FSX.
It is possible these days to obtain SRTM data greater than 90 metre resolution, but I don't know if that is available for NZ, and I don't know if it is used in this new mesh. Looking at the Milford screenshot suggests that this is based on newer data.