I am playing with SBuilder where a mesh at LOD8 is needed as a base to make hi-res scenery. I currently have STRM30 ( I assime this is 30m between points) which is close to LOD10. How do I convert it to LOD8 for use in SBuilder?Dick Boley @KLBE

>I currently have STRM30 (I assume this is 30m between points)Hi,Just to clear up a frequent confusion, the number "30" from "SRTM30" means arcseconds, not meters.http://www.src.com/datasets/SRTM30_Info_Page.htmlSRTM30 has the same horizontal grid spacing as GTOPO30, i.e., approximately (depends on the latitude) 1km.http://edcdaac.usgs.gov/gtopo30/gtopo30.aspHere

It's not easy - you need to resample the SRTM data (and as emerson points out, you've got a long way to go to LOD8!), however you can't just increase the size. Going from 3 arc second data which is 1201 pixels square, the increased 1 arc second data is now 3601 pixels. Don't simply increase the size by 300% or you'll get extra rows. SBuilder has a DEM tool to upsample for you, but i don't know if it will upsample 30 arc sec. After upsampling, you simply apply filters to your liking to smooth the results. I prefer to pick points that are known altitudes, and after smoothing, return and using "levels" in gimp, set those points back to the correct altitude...