ASTER GDEM Version 2

ai3dai3d Global Mapper UserPosts: 25Trusted User
edited April 2015 in GIS Data Sources
Is this dataset available yet as a built in to GlobalMapper. I couldnt find it.

If it is not, can we get it included as I believe its a 10m resolution DEM for the globe.

Thanks

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited May 2012
    I'm not aware of a server that's hosting that data in a way that it can be streamed into Global Mapper. If you know of one we would love to add it as a built-in source!

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • ai3dai3d Global Mapper User Posts: 25Trusted User
    edited May 2012
    Hi Mike

    I saw that it was available at the 3 sites here http://asterweb.jpl.nasa.gov/gdem.asp

    I assume that these do not allow streaming. Well hopefully they will allow streaming in the near future.
  • tjhbtjhb Global Mapper User Posts: 452Trusted User
    edited May 2012
    I think that's unlikely. It would be difficult to incorporate agreement to their usage policy (which is very open, but has specific limitations on dissemination).

    https://lpdaac.usgs.gov/products/aster_policies
  • JBourretJBourret Global Mapper User Posts: 2
    edited November 2013
    My goal is to utilize ASTER GDEM V2 map files to create a terrain profile along a great circle path. I have tried to figure this out on my own, but have yet to find success.

    Global Mapper opens the GeoTIFF files and allows me to view the metadata, but how can I simply view or understand how this file is structured? How can I have a program of mine read the GeoTIFF and get elevations along a great circle path?

    Any help would be greatly appreciated - thank you.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2013
    If you load the terrain GeoTIFF into Global Mapper you can use the Path Profile tool to draw your path and it should follow the great circle path by default. Then you will see the terrain surface on the path profile dialog. If you need to do this in your own application you could use the Global Mapper SDK to load the terrain GeoTIFF (use GM_LoadLayerList), then use GM_GetPathProfile to sample along a path or GM_GetLocationElevation to sample individual elevations along whatever path you need.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • JBourretJBourret Global Mapper User Posts: 2
    edited November 2013
    Hey Mike,

    Thank you so much for your reply - I really appreciate it. We have an existing program that does RF analysis based on terrain. We have the capability to use SRTM maps that are in 16-bit signed integer format (DTED 1). But we had information on exactly what was in the header: how many characters it was, where each piece of information was located in the header, and on what line the terrain matrix started.

    We would like to know the same header information for the GeoTIFF so we can read the data in the header and then skip to the first row of terrain data. I have been unable to locate any information that includes explicit details about the structure of the header. Could you or a source you know of provide this header information?

    Another option is to use Global Mapper to Batch Convert GeoTIFF files into DTED 2 files, but this seems like it may be less efficient.

    What do you think?

    Thanks,
    Jack
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2013
    Jack,

    The GeoTIFF format is much more complex than a flat DTED file so there isn't just a fixed offset to get to the data. There are libraries (libtiff and libgeotiff) for reading this data, but you might be a lot better off using something like the Global Mapper SDK as it will load a huge number of formats and then provide easy access to the data in the same manner for every format. See Global Mapper SDK for details on the SDK, including a download with samples.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • GayleShierGayleShier Global Mapper User Posts: 12Trusted User
    edited February 2014
    thanks for sharing the Global Mapper SDK .. i will do check it out
  • tmorristmorris Global Mapper User Posts: 1
    edited April 2015
    Hi,

    I see that in Global Mapper 16.1 that ASTER GDEM v2 is available as an online data source. However I am having an issue with the bit depth of the provided data. when I load this data set into my Global Mapper project and then export it as a 16bit .png I do not actually get 16bit data. The image properties list it as 16bit but upon close inspection you can tell that the exported heightmaps contain the same data as an 8bit image.

    That is, if I export the dataset as an 8bit .png and as a 16bit .png, both images are exactly the same.

    Is this an issue with the dataset or potentially an issue with my project?

    Thanks ahead of time.
Sign In or Register to comment.