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<p>Hi Steve,</p>
<p>Assuming lon=-100 lat=40 z=0, I believe (not sure! and in
particular if that's geodetically meaningful to chain so many
transformations) you should use a pipeline like the following one,
which will do:</p>
<p>- conversion to cartesian coordinate space</p>
<p>- apply the ITRF2000 to ITRF2014 transformation preserving
observation epoch of 2022.1</p>
<p>- apply the ITRF2014:NOAM model using a target epoch of 2010
(hence the +inv, as naturally the transformation would use
+t_epoch as the "source") for a point at observation epoch of
2022.1</p>
<p>- force the observation epoch to 2010</p>
<p>- apply the ITRF2014 to ITRF2000 transformation (at epoch 2010)</p>
<p>- conversion to lat, lon coordinate space<br>
</p>
<p>echo -100 40 0 2022.1 | cct -d 8 +proj=pipeline \<br>
+step +proj=cart +ellps+GRS80 \ <br>
+step +inv +init=ITRF2014:ITRF2000 \<br>
+step +inv +init=ITRF2014:NOAM +t_epoch=2010 \<br>
+step +proj=set +v_4=2010 \<br>
+step +init=ITRF2014:ITRF2000 \<br>
+step +inv +proj=cart +ellps+GRS80</p>
<p>I get:</p>
<p> -99.99999790 40.00000064 0.00755196 2010.0000<br>
<br>
</p>
<p>If using ITRF2008 instead of ITRF2014, I get:</p>
<p> -99.99999854 40.00000065 0.00909276 2010.0000<br>
</p>
<p><br>
</p>
<p>I've also tried using a plate-fixed CRS as an intermediate using
what is available in EPSG</p>
<p>First with NAD83(CORS96) since there's a direct transformation
for it in EPSG (not quite "direct" since when looking at the
comments, it already results from concatenation of ITRF96>97
and IERS ITRF97>2000 transformations)</p>
<p> (order is lat, lon here)</p>
$ echo 40 -100 0 2022.1 | cs2cs -d 8 "ITRF2000" "NAD83(CORS96)" |
cct -d 8 +proj=set +v_4=2010 | cs2cs -d 8 "NAD83(CORS96)"
"ITRF2000"<br>
40.00000067 -99.99999766 -0.00447640 2010.0000<br>
<br>
<p>Or if using NAD83(2011) (there's a transformation between
NAD83(2011) and ITRF2008 in EPSG (concatenation of ITRF96>97
and IERS ITRF97>2008 transformations), and PROJ will use the
ITRF2008 to ITRF2000 transformation in addition<br>
</p>
$ echo 40 -100 0 2022.1 | cs2cs -d 8 "ITRF2000" "NAD83(2011)" | cct
-d 8 +proj=set +v_4=2010 | cs2cs -d 8 "NAD83(2011)" "ITRF2000"<br>
40.00000066 -99.99999765 -0.00447668 2010.0000<br>
<p><br>
So results are somewhat consistent, at least in the lat, lon space
(not for z values)</p>
<p>Best regards,<br>
</p>
<p>Even</p>
<p><br>
</p>
<div class="moz-cite-prefix">Le 07/02/2022 à 14:49, Steve Riddell a
écrit :<br>
</div>
<blockquote type="cite"
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<p class="MsoNormal">The data for the ITFR2008 & ITRF2014
plate motion models are delivered with PROJ as init files.
From the documentation, 8.7, I think I see how an +init proj
string can be used for changing epochs between ITFR frames
(e.g. ITRF2000 to ITRF2005), but can someone please give an
example of using the plate models? For example, if I have a
point in ITRF2000 epoch 2022.1 and I want to use the NOAM
plate model to move it to 2010.0, what would be the +init
string? I’m assuming cct would be an appropriate application
for processing this string?</p>
<p class="MsoNormal">Thanks for any assistance!</p>
<p class="MsoNormal">Steve</p>
</div>
<br>
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