Global Mapper Pro

DEM from elevation contours - terrace effect

vax
vax Global Mapper UserTrusted User
edited December 2012 in Technical Support
Hello,

recently I tried to generate DEM from contours that have embedded elevation data. I made it through layer right-click/create elevation grid.

At places where elevation or slope direction changes rapidly - this is ridges or valleys, a terrace-effect can be observed.

It seems that this effect is typical for the algorithm used (probably) in GM. There is also a special one - called DEST - that is specifically designed to resolve the terracing effect. My question is - does Global Mapper support the DEST interpolation method and if so, how to enable it?

Comments

  • global_mapper
    global_mapper Administrator
    edited April 2011
    There is not currently any support for using the DEST resampling algorithm when creating DEMs from contours in Global Mapper.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • tjhb
    tjhb Global Mapper User Trusted User
    edited April 2011
    Mike,

    If you were curious about the difference DEST makes to "ordinary" triangulation, I could send a couple of examples from Manifold, one using DEST and the other not.

    It makes little difference for gridding very closely spaced data, such as LiDAR data, but a massive difference to gridding coarser data such as contours (with or without added height points). Having proper valleys and ridgelines everywhere makes the DEM substantially more "readable" and pleasing to the eye.

    Tim
  • global_mapper
    global_mapper Administrator
    edited April 2011
    Tim,

    I wouldn't mind seeing a couple of examples. Do you know if DEST is a documented algorithm somewhere or is it some custom Manifold thing that they have developed? I couldn't find any reference to it outside of Manifold.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • vax
    vax Global Mapper User Trusted User
    edited April 2011
    Hi Mike,

    here is a link to the original publication on the DEST interpolator - http://www.agu.org/journals/ABS/2004/2004JF000150.shtml
    I can also provide you several selected patches of vectorized contour lines, where the terrace effect is quite strong.

    Regards,
    vax
  • global_mapper
    global_mapper Administrator
    edited April 2011
    vax,

    Thanks, I'll add this to the todo list.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • stretch
    stretch Global Mapper User
    edited December 2012
    Wow, those DEST examples look impressive. Also worth considering for implementing in GM are some of the modules in GRASS http://grasswiki.osgeo.org/wiki/Contour_lines_to_DEM
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