Global Mapper v25.0

New Questions

global_noobie
global_noobie Global Mapper UserTrusted User
edited July 2010 in Elevation Data
I'm not a GIS expert and I don't want or need to be as my involvement in this side of things is simply getting data in DEM format and exporting it.

However, I do have some direct questions and I was hoping someone could point me in the right direction so I can learn what I need to know without being bogged down with a ton of stuff that comes with it.

1) I would like to edit some existing DEM data I imported into GM. Its of a coastal region and there are some jagged lines where I assume the points are being centralised to a vertice, or whatever lingo you would use, so I need some king of drawing mode when I can smooth out these areas.

I did look at the tut page and while the main one claimed to address it there, it seemed quite complicated. I was hoping for some kind of pen tool to make it nice and easy.

2)How difficult is it to make a DEM from a photo, and how would the accuracy of the data compare to some height data or say 5 to 10 meter intervals?
Is it just not worth doing by hand?

The software has been working great for exporting DEM's, but like I said, I think/hope it would be easier for me to edit the imperfection of the DEM at a 2D level than playing around with the 3D mesh.

If someone can help, or give me some links/directions to this area I would be grateful, I'm not lazy, I just sense this is an area with many different ways of doing the same thing and I would just like to know the global mapper way so I can do my very specific task.

Thanks for any help, will keep checking back over next few days.

Comments

  • global_mapper
    global_mapper Administrator
    edited July 2010
    There isn't really a direct way to edit DEMs in Global Mapper. Currently your best bet would be to right-click on the DEM layer of the Control Center and select the option to create 3D point features from the elevation grid cell centers. You could then edit the elevations of those points or delete the bad ones, then right-click on the point layer and select the option to generate an elevation grid. This will create a new DEM from the edited points.

    There is not any way in Global Mapper to create a DEM from aerial imagery.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • global_noobie
    global_noobie Global Mapper User Trusted User
    edited July 2010
    There isn't really a direct way to edit DEMs in Global Mapper. Currently your best bet would be to right-click on the DEM layer of the Control Center and select the option to create 3D point features from the elevation grid cell centers. You could then edit the elevations of those points or delete the bad ones, then right-click on the point layer and select the option to generate an elevation grid. This will create a new DEM from the edited points.

    There is not any way in Global Mapper to create a DEM from aerial imagery.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com


    Thanks,

    But what if the format I ge the height data in is NOT DEM?

    I'm exporting to DEM, when I import the height data I believe its in "Arc Ascii Grid", does that make any difference. It would be great to be able to draw little mounds with a few simple pen/brush tools and have it do the heigh stuff for me.

    With 3D terrains, it does not have to be super accurate anyway, at leas for 3D visualisation and its a lot easier doing this at a 2D level than a fully 3D model.
  • global_mapper
    global_mapper Administrator
    edited July 2010
    It doesn't matter what your original terrain data format is, Global Mapper can export any loaded terrain surface to a new DEM format file.

    You can also do some terrain creation/editing by drawing an area feature using the Digitizer Tool for an area and providing an elevation attribute for it, then selecting that area with the Digitizer Tool, then right-clicking and selecting the Advanced Feature Creation option to create/flatten terrain from the area. Do this wherever you need mounds or something similar to create new terrain layers on top of whatever you have loaded, then you can export that to a new DEM combined with your other loaded terrain data.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • global_noobie
    global_noobie Global Mapper User Trusted User
    edited July 2010
    Thanks for the prompt communique'.