LIDAR and Gridding

txrplstxrpls Global Mapper UserPosts: 83Trusted User
edited April 2014 in Elevation Data
I am having a heck of a time getting a grid to construct where there is blank data from ground filtering in the LAS file. This has worked for me before. Am I holding my lips wrong? BTW the help file for griding is way out of date.

Mark

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2014
    Mark,

    Are you using the Grid Tightness slider when doing the gridding. You'll want that towards the loose setting to fill in gaps where there is no data.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    Thanks Mike. I knew I was holding my lips wrong. I have used the Lidar module to process a few projects that I have flown with my eBee UAV with great success. The last land I flew is giving me fits. Using the auto classify ground option, I either filter to much or not enough. Is it possible to select different areas and select the min elevation in that area and reclassify those points?
  • CassandraQCassandraQ Global Mapper User Posts: 34Trusted User
    edited April 2014
    A specific geographic area can be selected when running the Automatic Ground Point classification function by selecting the "Specify Bounds" button in the lower left side of the dialog box. Polygon features can be used to specify the geographic bounds of the operation as well as lat\long or by drawing a box. A minimum value can be entered for that area.

    Thanks,
    Cassandra
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    CassandraQ wrote: »
    A specific geographic area can be selected when running the Automatic Ground Point classification function by selecting the "Specify Bounds" button in the lower left side of the dialog box. Polygon features can be used to specify the geographic bounds of the operation as well as lat\long or by drawing a box. A minimum value can be entered for that area.

    Thanks,
    Cassandra

    Hi Cassandra,

    I know that. The issue is that auto ground classification is not working as well with this file. What I am thinking is to select a treed area with a polygon and sorting that area by elevation and selecting the lower points and classifying them as ground points. I think this should be possible.

    Mark
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Mark,

    In the very near future I plan on adding an option to filter selected Lidar points by elevation (among other things), but for now what you could do is use the Path Profile tool and draw a path through your data, then on the menu for the Path Profile dialog select to change the corridor width and make it much wider, which should give you a path profile with all of the points near the path. You can then easily select them in a side view and classify them as needed right in the path profile dialog.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    Thanks Mike, I knew you would have a solution. I thought in one of the webinars that you could also sort the data by elevation in a table.

    -Mark
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Mark,

    You can use the Search option (binoculars on toolbar) to see all of the attributes of the loaded data, including Lidar, and sort by elevation. You can also search just on-screen features, so you could zoom to an area of interest, then open the search and select to search on-screen only, then sort by elevation and select and edit that way.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    Mike,

    Thanks, I was just playing with that. It would be nice if the seach had an option to use a polygon boundary.

    Mark
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Mark,

    If you first select by polygon in the Digitizer Tool there is now a 'Search Selected Features' button on the search dialog so you can search only those features selected in the Digitizer Tool, which should allow you to do that.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Global Mapper
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    Is that something you just added?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Yes that's something new in the last month or so. If you get v15.1.8 from Global Mapper Downloads it includes that change.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    Mike,

    Unless I have done something wrong, there is no binning options in the grid creation dialog. is this a bug that crept in?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Are you trying to grid only Lidar point cloud data? The binned gridding methods only apply to Lidar point clouds. If you have anything else included in the gridding, including lines, areas, or normal points, the binned gridding methods will not be available.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • txrplstxrpls Global Mapper User Posts: 83Trusted User
    edited April 2014
    That was the problem. Somehow I got an area feature in the data.
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