[Talk-us-massachusetts] Fwd: GPS on Benchmarks Campaign from the National Geodetic Survey

[Andy Anderson]

Thanks, Greg, that’s really helpful!

— Andy

> On Apr 15, 2021, at 3:27 PM, Greg Troxel <gdt at lexort.com> wrote:
> 
> 
> Andy Anderson <aanderson at amherst.edu> writes:
> 
>> The implication is that they don’t have good information about the
>> location of most of these.
> 
> I was skeptical of this suggestion (that navigation-solution positions
> owuld be helpful), but their page indeed says they want non-survey-grade
> measurements of marks that are marked "SCALED" meaning they guess the
> location from a topo map.  I don't think there are that many of those.
> 
> They also want recovery notes for marks that have not been recovered in
> 30 years.
> 
> They do want survey-grade ellipsoidal height measurements of benchmarks.
> 
> https://www.ngs.noaa.gov/GPSonBM/
> https://www.ngs.noaa.gov/GPSonBM/observe.shtml
> 
> You can get a shapefile of all the marks via the database search page at
> 
> https://www.ngs.noaa.gov/datasheets/index.shtml
> 
> I've attached a screenshot of loading that layer into QGIS with an OSM
> basemap.
> 
> I was then able to do category-based symbolization and find the ones
> marked "scaled".  An example is
> 
> https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=MY2109
> 
> 
> 
> 
> <marks.png>

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