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GeoTIFF exports for ArcGIS

dcoggindcoggin Global Mapper UserPosts: 259Trusted User
edited March 2010 in Technical Support
Mike,

I have to share DEMs I've produced with other companies and am trying to switch from FLOATGRID to GeoTIFF for sharing with ArcGIS-using colleagues. When I first sent Global Mapper produced 32-bit floating point elevation value GeoTIFFs to another company using ArcGIS they say the GeoTIFFs appear to have no elevation change (all one solid color). They look fine in Global Mapper. I then downloaded a small sample of the USGS NED DEM in GeoTIFF format and sent that to the other company to try. They can view that fine in ArcGIS and view elevation values. Global Mapper displays both. The ArcGIS user says that he cannot view any statistics for the Global Mapper GeoTIFF but can view statistics for the USGS GeoTIFF. I did provide the .AUX file for the downloaded USGS GeoTIFF, so I'm not sure if that makes a difference. The only thing I noticed as different looking at the metadata for the two tiles in Global Mapper was that the USGS GeoTIFF uses "Pixel is Area" as opposed the Global Mapper that uses "Pixel is Point". Any ideas?

Thanks for the new Global Mapper version. I haven't used it yet, but was very happy to see the new legend development tool.


David

Comments

  • dcoggindcoggin Global Mapper User Posts: 259Trusted User
    edited March 2010
    In case it helps, I sent copies of both GeoTIFFs, one from GM, one from USGS, to the Support e-mail.

    David
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    David,

    I took a look but couldn't find anything obvious that would cause ArcGIS to not like the Global Mapper files. The Global Mapper file does use 'Pixel is Point', but that is actually the more common interpretation for elevation GeoTIFF files. The 'Pixel is Area' interpretation is normally used for images. The other difference that I found was that the USGS file was missing some tags, like a min/max sample/elevation range, that the Global Mapper file does generate.

    Do the 16-bit elevation GeoTIFF files from Global Mapper work in ArcGIS? Have you tried supplying a 32-bit file to the ArcGIS support to see if they can answer why they don't work? The .aux files are a proprietary ESRI format for storing statistics about the file, but should not be required.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • dcoggindcoggin Global Mapper User Posts: 259Trusted User
    edited March 2010
    Mike, I don't have ArcGIS so I can't get support, but I did export a 16-bit version and sent that to an ArcGIS friend along with a sample GeoTIFF downloaded from the USGS NED DEM that I sent without the .aux file. As I expected ArcGIS can't read either. It's the .aux file that makes the difference.

    ESRI provides a Python script to import FLOATGRID to automate that import, but it's still not easy for some users. I'm wondering if there is another format that ArcGIS will import in a more friendly manner. If I don't get any answers from this post I may start a new thread as I expect some Global Mapper users have dealt with the same problem. Thanks for looking into it Mike. It's frustrating that as big as ESRI is they can't provide a little more interoperability in their products.

    David
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    David,

    You should be able to use the Arc ASCII Grid format with ESRI products easily, although knowing them it probably requires an expensive add-on just to add one format.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • dcoggindcoggin Global Mapper User Posts: 259Trusted User
    edited March 2010
    Yes, I was just trying to avoid the ASCII grid as I work with very large (multiple county) areas.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2010
    You could also try a BIL export. It would be smaller than an Arc ASCII Grid, but would still be large as it's uncompressed.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • kbrown67kbrown67 Global Mapper User Posts: 3
    edited March 2010
    dcoggin wrote: »
    Mike, I don't have ArcGIS so I can't get support, but I did export a 16-bit version and sent that to an ArcGIS friend along with a sample GeoTIFF downloaded from the USGS NED DEM that I sent without the .aux file. As I expected ArcGIS can't read either. It's the .aux file that makes the difference.

    ESRI provides a Python script to import FLOATGRID to automate that import, but it's still not easy for some users. I'm wondering if there is another format that ArcGIS will import in a more friendly manner. If I don't get any answers from this post I may start a new thread as I expect some Global Mapper users have dealt with the same problem. Thanks for looking into it Mike. It's frustrating that as big as ESRI is they can't provide a little more interoperability in their products.

    David
    Suggest to your ArcGIS user to delete the existing .aux file for the image you are referencing. As Mike suggested, the .aux file contains statistics for the image file. If you reprocessed the image and saved by overwriting the original, the results in ArcMap will be effected by the original .aux file and the image will be displayed as the original file was. By deleting the .aux file and then re-opening the image in ArcMap, a new .aux file will be created based on the reprocessed image and it will display correctly!
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