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Don't know about your overall problem but NGA is probably the
National Geospatial Agency and NOAA is National Oceanic and
Atmospheric Agency: i.e., not just a typo.<br>
<br>
J.<br>
<br>
<div class="moz-cite-prefix">On 7/1/20 16:49, Patrick Young wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CADXYQQ668tVgz0g5ZzNfCTPKSnG9up1tQ7d6c59+QcrtagOKRw@mail.gmail.com">
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<div dir="ltr">Hello,
<div><br>
</div>
<div>I am trying to figure out how to convert some elevations I
have into heights above ellipsoid via the cs2cs tool. I am
using proj 7.0.1, and I've run projsync --all to snag all the
grids.</div>
<div><br>
</div>
<div>Here is an example of what isn't working for me:</div>
<div><br>
</div>
<div>echo 565890.947 4192011.754 55 | cs2cs +proj=utm +zone=10
+datum=NAD83 +units=m +no_defs +geoidgrids=us_noaa_g2018u0.tif
+to +proj=utm +zone=10 +datum=NAD83 +units=m +vunits=m
+no_defs<br>
565890.95 4192011.75 55.00<br>
</div>
<div><br>
</div>
<div>I am confused as to why the elevation value isn't changing
for me. My (extremely limited) understanding is that I am
asking for 55m to be converted from a height referenced
against the NADV88 geoid to one referenced against the NAD83
ellipsoid. Am I using the wrong geoid grid? From the grid
readme, it mentions "us_nga_g2018u0.tif : Conterminous US,
referenced to NAD83(2011). Vertical datum: NAVD88"
(presumably the nga <-> noaa is a typo in the readme) so
I think I'm using the right one.</div>
<div><br>
</div>
<div>Thanks for any help,</div>
<div>Patrick</div>
</div>
<br>
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<br>
<pre class="moz-signature" cols="72">--
John Helly, University of California, San Diego / San Diego Supercomputer Center / Scripps Institution of Oceanography / 760 840 8660 mobile / <a class="moz-txt-link-freetext" href="http://www.sdsc.edu/~hellyj">http://www.sdsc.edu/~hellyj</a>
ORCID ID: orcid.org/0000-0002-3779-0603</pre>
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