[Talk-us-massachusetts] Braintree buildings+(Datum shift)

[Andy Anderson]

Thinking about this more, in the context of what they are trying to do with the new IGS and its relationship to the new North American Terrestrial Reference Frame of 2022, the NAD83 and WGS84 relationship might be more of a parallel development  — NAD83 could have been designed with the same understanding of the geoid that was used shortly thereafter to define WGS84, and for that reason they ended up being closely aligned in North America.

> On Dec 31, 2019, at 9:18 AM, Greg Troxel <gdt at lexort.com> wrote:
> 
> Andy Anderson <aanderson at amherst.edu> writes:
> 
>> My understanding is that because there is a degree of freedom in
>> choosing these, WGS84 was designed to match well in North America.
> 
> I have never heard that, and my understanding is that the design aimed
> for a global fit.
> 
> Yes, NATRF2022 is coming.  I expect that at some point MassGIS will
> convert.  I also expect precise transformations to be published.  So
> this will not be mysterious, but something we need to be careful about.
> 
> As for epcoh of measurement - that's something that OSM has no concept
> of now, so it basically remains an error source.  As far as I can tell
> GIS in general is not really dealing with that.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 529 bytes
Desc: Message signed with OpenPGP
URL: <http://lists.openstreetmap.org/pipermail/talk-us-massachusetts/attachments/20191231/a88d2f0c/attachment.sig>