Hi Steve,
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:
- conversion to cartesian coordinate space
- apply the ITRF2000 to ITRF2014 transformation preserving observation
epoch of 2022.1
- 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
- force the observation epoch to 2010
- apply the ITRF2014 to ITRF2000 transformation (at epoch 2010)
- conversion to lat, lon coordinate space
echo -100 40 0 2022.1 | cct -d 8 +proj=pipeline \
+step +proj=cart +ellps+GRS80 \
+step +inv +init=ITRF2014:ITRF2000 \
+step +inv +init=ITRF2014:NOAM +t_epoch=2010 \
+step +proj=set +v_4=2010 \
+step +init=ITRF2014:ITRF2000 \
+step +inv +proj=cart +ellps+GRS80
I get:
-99.99999790 40.00000064 0.00755196 2010.0000
If using ITRF2008 instead of ITRF2014, I get:
-99.99999854 40.00000065 0.00909276 2010.0000
I've also tried using a plate-fixed CRS as an intermediate using what is
available in EPSG
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)
(order is lat, lon here)
$ 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"
40.00000067 -99.99999766 -0.00447640 2010.0000
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
$ 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"
40.00000066 -99.99999765 -0.00447668 2010.0000
So results are somewhat consistent, at least in the lat, lon space (not
for z values)
Best regards,
Even
Le 07/02/2022 à 14:49, Steve Riddell a écrit :
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?
Thanks for any assistance!
Steve
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