[PROJ] WGS84/NAD83 Original to {current} transforms

[mhw-at-yg]

Hello,

Within the Yukon and NWT (Canada), how do you convert spatial data
horizontal datum from NAD83-Original (circa 1994) to NAD83-CSRS (2002+)?

I’ve been up and down NRCAN’s geodetic reference site[0] and a bunch of
other ones and am more confused than when I started. The consensus on the
net seems to be to use NTv2 to migrate from Original to CSRS, but there are
no grid shift files for the territories [1],[2].

Esri (ArcGIS Desktop) and Safe (FME) use transforms which are a null
operation, all that happens is a change in the name, the coordinates are
left unaltered. However looking at the v7 velocity grid[3] it looks like
there have been significant shifts since the 1990s.

Most of our new data acquisitions from survey and LiDAR are coming in as
CSRS. When combining with our old data and project-on-the-fly I’ve observed
different coordinates for the same points depending on how the locations are
reported. So we need to bring our holdings into a common coordinate system
to be assured our analyses are the most correct they can be, but how?

[0]:
https://www.nrcan.gc.ca/maps-tools-and-publications/tools/geodetic-reference-systems/18766
[1]: https://webapp.geod.nrcan.gc.ca/geod/tools-outils/grids.php (List)
[2]: https://webapp.geod.nrcan.gc.ca/geod/data-donnees/transformations.php
(Download, sign in but free account)
[3]: https://webapp.geod.nrcan.gc.ca/geod/tools-outils/nad83-docs.php

Thanks in advance for your advice,

Matt Wilkie
Geomatics Analyst
Environment | Information Management & Technology
T 867-667-8133 | Yukon.ca




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-Matt
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