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Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

  • 1.  Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-06-2019 16:53

    I'm not sure how Trimble creates their .ggf files, but on Monday December 9th the NGS is going to announce:

     

     

    NGS Industry Partners-

    I am writing to give you advance notice of a Critical Update to the GEOID18 little endian and ascii grid files. If you or your team downloaded and used either of these grid file types prior to November 26th, 2019 we urge you to replace them with the files currently available on the GEOID18 Downloads page. NGS will issue the public announcement copied below at around 4:00 pm Eastern Time, on Monday, December 9th. Please consider sharing this advance warning with any of your colleagues that may be affected by this update. 

     

    I assume these specific files are not the source material for Trimble's .ggf, but I'm hopeful for a little reassurance before I push out some deliverables derived from Trimble's Geoid18 file.

     

    Thanks!



  • 2.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-10-2019 15:12

    Hi David,

     

    The current Geoid 18 file indeed affected by the incorrect the source file. Rest assured, this issue is known to developers and an update is currently being verified by our QA team. 

     

    I would suggest holding off on using Geoid 18 ggf files until we implement the updated files.

     

    -Josh



  • 3.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-10-2019 15:18

    Joshua,

     

    We've already delivered some projects in GEOID18, and are in the middle of the pipeline for some others.  Unfortunately these potentially impacted projects aren't geographically isolated.  Will there be, or could there be, a map made (or even just a list) of the affected grid cells so that we could check if we are impacted?

     

    Thanks!

     

    -David



  • 4.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-10-2019 15:22

    I don't believe the TBC team will be releasing any releasing any resources detailing the affected areas. I would suggest reaching out to NGS directly with your request. 

     

    -Josh



  • 5.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-12-2019 15:34

    You can get a copy of the Trimble Grid Factory and make your own GEOID18 .ggf fils from the new raw data and bring it into your data collector or TBC or just grab one that I made and posted here Get the Geoid18 files that work in your data collector 



  • 6.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-12-2019 15:45

    I'm not so worried about getting a safe .ggf file at this point, though I appreciate the information, but rather I'd like to be able to quickly identify how many of my delivered projects since the September 10th changeover from 12B to 18 are impacted by these few erroneous grid cells.  The cost of redoing dozens of projects wouldn't be cheap.



  • 7.  Re: Does the NGS Critical Update of their GEOID18 little endian and ascii grid files impact Trimble's Geoid18US.ggf files?

    Posted 12-12-2019 16:16

    The measured ellipsoid heights won't change so just reprocess with the new GEOID18 and compare the orthometric heights.