Is the reference to an online connection to 10m DEMs correct?

I don't think it is for a couple of reasons.  In the metadata the pixel size is about 9.55m.  I have a 10m DEM for the quadrangle I'm working in and the pixels are 10m.  Also if you follow-the data source link it takes you to USGS site and the National Map and further clicking on links dead ends before the old 10m DEMs.  It appears that only the USGS NED 1/3 arc-second 1 degree ArcGrid files are now available through the federal sites.  Is Global Mapper accessing that data source?  As a test, I compared10-ft interval contours generated with the online Global Mapper data to 10-ft interval countours from the downloaded 10m DEM.  They differ.

I'm using the contours to estimate ground surface and I need to be able to reference my source data.  Because of the difference in the contour sets, I really don't want to "do over" so I can reference them to a source that I am confident others can get the same results with. 

Any clarification would be helpful.  Thanks.

Answers

  • bmg_bobbmg_bob Global Mapper Programmer Posts: 1,681
    Hello,

    I suggest that you contact Blue Marble Geographics support directly via e-mail (geohelp@bluemarblegeo.com) to get this question answered.

    Cheers,
    Bob
  • MicheleMichele Posts: 28
    With all due respect,
    In these cases, where no data is attached or attachable to show the problem, wouldn't be better to answer here on the forum so, in the future, people that search for an answer for this kind of question, can find it directly?
    Recently I noticed a lot of questions that were answered with "send your data to Blue Marble". This doesn't build a base of knowledge accessible to other users and only makes you spend time answering it every time it is asked.
    Sorry for the Out of Topic and Best regards
    Michele
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