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Thread: Atoll DTM resolution

  1. #1
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    Default Atoll DTM resolution

    Hi,

    I am using this guide to create maps for Atoll: https://tholeibrahim.wordpress.com/2...tion-in-atoll/

    Works flawlessly, the only issue is that the DTM data I have access to has 0.5 meter resolution, really high res LiDar scan is the source. In some cases, you can see even the truck tracks in the sand on it. But when I convert it with GlobalMapper, the resolution drops quite a bit by the time I import it to Atoll.

    I noticed that if I try to select a lower than 1 meter Sample Spacing when I export the GRD data from Global Mapper, Atoll won't be able to import it, 1 meter seems to be the lowest Atoll accepts.

    Question is, can I keep the resolution as good as the source data somehow when I export from GlobalMapper to Atoll?

    This is how my GlobalMapper export settings looks like atm: GlobalMapper.jpg

    Thanks in advance!

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  3. #2
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    Default Re: Atoll DTM resolution

    Hi!
    What is the size of the DTM file created in Global Mapper? What is the size of the imported DTM file in Atoll?

    BR Slava

  4. #3
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    Default Re: Atoll DTM resolution

    The diff is huge. The original DTM is 490MB, the output is 64MB. Same exact area. The input is a TIF file.

    If I lower the Sample Spacing in GlobalMapper from the current 1 meter to 0.5 meters, the output is 240MB, but Atoll is not willing to import anything below 1 meter, it specifically complains about it.

    This is how it looks when I try to import a 0.5 meter Sample Spacing export into Atoll:

    Atoll_import_fail.jpg
    Last edited by subway; 2022-08-24 at 09:27 PM

  5. #4
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    Default Re: Atoll DTM resolution

    what is the format of the imported file?
    BR Slava

  6. #5
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    Default Re: Atoll DTM resolution

    Quote Originally Posted by slava121 View Post
    what is the format of the imported file?

    The LiDar scan is in TIF format, that is imported into Global Mapper. Then it is exported from Global Mapper in Vertical Mapper Grid file (GRD), which is imported to Atoll.

  7. #6
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    Default Re: Atoll DTM resolution

    try to export the file in 5 meters resolution and import it into Atoll.
    BR Slava

  8. #7
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    Default Re: Atoll DTM resolution

    Quote Originally Posted by slava121 View Post
    try to export the file in 5 meters resolution and import it into Atoll.

    I am already at 1 meter resolution, why would I try 5 meters? Question is how to go below 1 meter so that Atoll accepts it.

  9. #8
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    Default Re: Atoll DTM resolution

    There is no information in Atoll what is the minimum resolution allowed when importing . a file with a resolution of 1 meter is loaded into Atoll?
    BR Slava

  10. #9
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    Default Re: Atoll DTM resolution

    Quote Originally Posted by subway View Post
    I am already at 1 meter resolution, why would I try 5 meters? Question is how to go below 1 meter so that Atoll accepts it.
    Hi, in GM try different ways of resampling, when choose 1m resolution to export

  11. #10
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    Default Re: Atoll DTM resolution

    Hi subway, try ticking the "Always Generate Square Grid Cells" box in the export settings, which you have unticked in your GM capture above. Years ago I did some test with exporting BIL terrain data out of Global Mapper, some tools could handle 32 or 16 bit non-square pixels (like Radio Mobile), whereas other tools would only work with square pixels (like Pathloss). I haven't used Atoll in anger, so can't hep you with that side of things but the square pixel thing is worth trying. Note that non-square pixel datasets will be smaller than square pixels.

    BR's, Stan.

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