Global Mapper v25.0

cutting holes in DEM

dstapp
dstapp Global Mapper User
edited December 2013 in Elevation Data
Hello - I have to two DEM's with different accuracies (30m and 10m). The 10m is surrounded by the 30m and I would like to combine them into one DEM. When I File>Export>Elevation Grid the resulting DEM file size is way bigger than the two combined. Not sure what happened but that wont work for me. Essentially I'd like to cut a hole in the 30m from the 10m boundary and combine the two keeping the respective accuracies.

Thanks in advance,

Dave

Comments

  • global_mapper
    global_mapper Administrator
    edited December 2013
    Dave,

    If you combine them into one they will both be resampled to the same accuracy, so if you export at 10m resolution the 30m resolution part will be 9 times the size. The only format that will keep them at their originals is the Global Mapper Package format, but of course that's only usable in Global Mapper.

    I could suggest enabling feathering for the 10m layer so it smoothly blends into the 30m data (do this on Feathering tab of Options dialog for 10m layer), but your output will still be much larger if you have to have everything in one file. If you need just one layer and format isn't important the Global Mapper Grid format is also a good option as it compresses extremely well, but it too only works in Global Mapper.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation