GlobalMapper and Erdas IMG format

PatGPatG Global Mapper UserPosts: 54Trusted User
edited June 2011 in Bug Report
Mike,
We have come across an issue with IMG raster elevation files exported from GlobalMapper v11.01.

I have attached a copy of a GM surface and the corresponding corrected ERDAS surface. The issue is that ERDAS will not read the embedded header info that Global mapper creates and it does not recognize that there is elevation information also (see error message screen grab). So you have to delete the projection information re-add it and then add the elevation info within Erdas.

Can you advise if this is easily fixed?

PS I have tried uploading my zip file with the "Manage attachments" but I had to use the "Basic uploader" to see my file in the attachment window. It would then not close the window when selecting "done" (nothing happened) and I could not see the attachment in the "preview post" option. Am I missing something here?

PPS Tried the attachment upload again after posting this message and editing and this seemed to work as expected and I can now see the attachment.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited May 2011
    Pat,

    Can you first try getting the latest v11.02 build of Global Mapper to see if that makes a difference? I have placed a new build at http://www.globalmapper.com/global_mapper11.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v11.xx installation folder to give it a try. If you are using the 64-bit v11 version there is a new build at http://www.globalmapper.com/global_mapper11_64bit.zip .

    I don't have Erdas Imagine, but both files load fine into Global Mapper. There were some changes made to how datum information was written to .img files prior to the v12 release so there might be something different in the v11.02 build that fixes this for you. The projection looks like a pretty standard one.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • PatGPatG Global Mapper User Posts: 54Trusted User
    edited June 2011
    Mike,
    Tried it in ver 11.02 and issue is still there. I tried a demo copy of ver 12 but as it is unable to export data I can't successfully test it. Looks like I will need to upgrade to be able to check.

    PS: Your response was so quick it must be a record but I just wanted to say how much it is appreciated....
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    Pat,

    If you email me at support@globalmapper.com I can give you a demo license to try v12.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • PatGPatG Global Mapper User Posts: 54Trusted User
    edited June 2011
    Mike,
    We tested ver 12 and have found the same problem. Raster or Elevation data exported by GM in ERDAS "img" format cannot be loaded properly in ERDAS IMAGINE 2011. The errors are as described in my top post. Would it be possible to look into this?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    Pat,

    I took a look and it appears that the problem was the name stored for the spheroid by Global Mapper was 'WGS84' rather than 'WGS 84' (note the space), which apparently breaks Erdas. I have updated the name stored by Global Mapper so you can test that. I have placed a new build at http://www.globalmapper.com/global_mapper12.zip with the change for you to try. Simply download that file and extract the contents into your existing v12.xx installation folder to give it a try. If you are using the 64-bit v12 version there is a new build at http://www.globalmapper.com/global_mapper12_64bit.zip .

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • PatGPatG Global Mapper User Posts: 54Trusted User
    edited June 2011
    Mike,
    We tried the new ver 12 after downloading (we are running the 64bit) but we are still getting the same error. For some reason ERDAS still does not recognise the spheroid and won't load the file properly. I will try and look at the same image output by ERDAS and GM in binary to see where the Headers differ and maybe that will show something up....
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    Pat,

    So you get the exact same error, or does it now say that the 'WGS 84' spheroid is not recognized rather than just 'WGS84'? That was the change made, the addition of the space. I wonder if this is something new that only affects ERDAS 2011, this is the first type of report like this and the storage of the WGS84 datum has been the same for a while. I don't suppose you could provide a file to ERDAS support and see if they can shed some light on the situation.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • PatGPatG Global Mapper User Posts: 54Trusted User
    edited June 2011
    Mike,
    Our operator has already gone home for today but I believe that the error now comes up with "WGS 84 Spheroid" not recognised. I will send the test images that we have recently produced from both ERDAS and GM12 to our ERDAS support and ask them to tell us what the problem might be. They are likely to be able to very quickly identify what the issue might be...

    Standby for further update once I have received their response...
  • PatGPatG Global Mapper User Posts: 54Trusted User
    edited June 2011
    Mike,
    I have the same TIFF image saved as an IMG format using ERDAS and GM12. Looking at the Headers it would appear that the GM version is not completely writing the Header correctly. I have attached screen grabs of the binary files and you can clearly see that the GM version appears to missing a portion of the projection info as if it has been truncated part way through. If you look at the top row in the ERDAS file you see the word "projection". In the GM12 version it appears as only "ion" missing the "project" portion of the word. Also The "WGS 84" that appears in the ERDAS version is completely missing in the GM12 version.

    Let me know if this narrows down the problem...
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited June 2011
    Pat,

    I will have to investigate, the Erdas .img files are read and written using an open source library in Global Mapper so I'm not personally familiar with what the format looks like. I think from looking at a couple of samples really fast though that Global Mapper is just writing the data out in a different order than Erdas, but I'm not completely sure yet.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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