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Import mesh with no geo-reference

GolfgraffixGolfgraffix Global Mapper UserPosts: 35Trusted User
edited February 2010 in Elevation Data
Hi all,

Let me start by saying that i dont come from a mapping background so I hope my question makes sense.

I have an xyz file that contains elevation data for a 2km x 2km plot I also have a geotiff aerial image of the same area. If i create an elevation grid from the xyz file how do i get it to line up with the geotiff?

John

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited January 2010
    John,

    If your XYZ coordinates are in some map projection system then just selecting the proper projection system on import for the data should automatically make it line up.

    Otherwise what you can do after loading and gridding the XYZ file you can right-click on it in the Control Center and select the option to Reposition the layer, then use control points to align it with the GeoTIFF image of the area.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • GolfgraffixGolfgraffix Global Mapper User Posts: 35Trusted User
    edited February 2010
    Thanks Mike, Worked perfectly.

    I have another related question. I have imported the DXF and created an elevation grid from the height data and have rectified the aerial image.

    The elevation grid is an irregular shape and the aerial is square but bigger than the elevation grid. Therefore parts of the aerial have no height data associated. How would i go about importing some SRTM data to fill the gaps?

    Maybe an image will help explain better

    Image.jpg
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2010
    You can use the File->Download Online Imagery/Data menu command and pull in SRTM data from there. Just move it before the other layers in the Control Center to put it behind them. If your golf course is in the US I would recommend instead using the NED data set as it it much higher resolution that the SRTM data (i.e. 30m spacing instead of 90m spacing).

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • GolfgraffixGolfgraffix Global Mapper User Posts: 35Trusted User
    edited February 2010
    Thanks Mike,

    I had already tried what you explained but am having a problem where the two meshes meet.

    As i mention the DXF has an irregular shape, where it meets the SRTM data it has a very sharp edge. Is there any way to fix this?

    [IMG]http://www.golfgraffix.com/Untitled-1 copy.jpg[/IMG]
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2010
    You can fix this by using the feather blending feature in Global Mapper and feather blending to the polygonal boundary of your data. See http://globalmapper.com/helpv11/Help_ControlCenter.html#raster_feathering_tab for details on how to setup feather blending to smooth layer boundaries.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • GolfgraffixGolfgraffix Global Mapper User Posts: 35Trusted User
    edited February 2010
    Hi Mike

    Can you explain this feathering reature a bit more, I just cant seem to get it to work

    J
  • tjhbtjhb Global Mapper User Posts: 454Trusted User
    edited February 2010
    Feathering can be applied only around the edges of the whole raster—i.e. of its rectangular extent—irrespective of the visibility of pixels along any given edge.

    It's possible that what you want is feathering around the edge of the visible pixels of the raster. As far as I know, that is currently only possible in GM using a polygon to represent the shape of the visible pixels.

    It can be quite hard to make such a polygon, given a raster in which the visible pixels form an irregular shape. There's no way to do that in Global Mapper—again, as far as I know.
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