Filtering small elevation grid data

stihlstihl Global Mapper UserPosts: 52Trusted User
edited March 2014 in Elevation Data
Hello,

Is it possible to filter out a set size of loose data in an elevation grid in GM v15.1?

For example; filter out any data that's larger than a set size.


Thanks

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2014
    I'm not quite sure what you mean. Do you want to filter out certain elevation ranges from the grid?

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • stihlstihl Global Mapper User Posts: 52Trusted User
    edited March 2014
    Hi Mike,

    What I mean is the following.

    The screenshot shows a current project. What I'd like to do is to filter out all the small seperate grid areas that do not belong to any bigger chunk.

    The greenish chunks represent cementblocks that are there to protect the coast against the waves. The blue noise is mostly water. I've tried getting rid of most of the water by altering the elevation values and then exporting the new elevation grid. However the unaesthetic noise remains. Any way to smoothen it or filter it out by using a fixed sample size or anything like that?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2014
    It looks like it might be best to draw a polygon with the Digitizer Tool around the data you want to keep, then select that with the Digitizer Tool, then go to the Cropping tab of the Options dialog for the grid layer and select the crop the data to the selected area. Then all of the data outside the selected area(s) will be treated as invalid.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • tjhbtjhb Global Mapper User Posts: 454Trusted User
    edited March 2014
    How about exporting a copy of the data with a strong median filter applied, then setting the original data to 0 (or whateer sea level is) wherever the smoothed copy is 0.
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