[Qgis-user] ITRF00

[Even Rouault]

On vendredi 13 décembre 2019 12:00:23 CET malcolm wrote:
> Question on how QGIS chooses its transformations. I am assuming it is from
> some proj defaults?? I want to know because I do not see the current
> NAD83<>WGS84 transformation (ITRF00) which is used by HAZUS and Esri. Is
> there any way to add this upstream so it is used if not by default at least
> as an option in QGIS?

Which transformations do they use ?

I can get non-null transformations with PROJ if using NAD83(2011) as source 
CRS and ITRF2000 as target:

They go through ITRF2008 or ITRF2014 as intermediate. However as those are 
time-dependent transformations, you'd need to specify a coordinate epoch to 
get very accurate results, which is not (yet?) possible through QGIS AFAIK.


$ projinfo -s "NAD83(2011)" -t ITRF2000 --spatial-test intersects -o PROJ
Candidate operations found: 2
-------------------------------------
Operation n°1:

unknown id, Conversion from NAD83(2011) (geog2D) to NAD83(2011) (geocentric) + 
Inverse of ITRF2008 to NAD83(2011) (1) + Inverse of ITRF2000 to ITRF2008 (1) + 
Conversion from ITRF2000 (geocentric) to ITRF2000 (geog2D), 0.01 m, USA - 
CONUS and Alaska; PRVI

PROJ string:
+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert 
+xy_in=deg +xy_out=rad +step +proj=cart +ellps=GRS80 +step +inv +proj=helmert 
+x=0.99343 +y=-1.90331 +z=-0.52655 +rx=0.02591467 +ry=0.00942645 
+rz=0.01159935 +s=0.00171504 +dx=0.00079 +dy=-0.0006 +dz=-0.00134 
+drx=6.667e-05 +dry=-0.00075744 +drz=-5.133e-05 +ds=-0.00010201 +t_epoch=1997 
+convention=coordinate_frame +step +inv +proj=helmert +x=0.0019 +y=0.0017 
+z=0.0105 +rx=0 +ry=0 +rz=0 +s=-0.00134 +dx=-0.0001 +dy=-0.0001 +dz=0.0018 
+drx=0 +dry=0 +drz=0 +ds=-8e-05 +t_epoch=2000 +convention=position_vector 
+step +inv +proj=cart +ellps=GRS80 +step +proj=unitconvert +xy_in=rad 
+xy_out=deg +step +proj=axisswap +order=2,1

-------------------------------------
Operation n°2:

unknown id, Conversion from NAD83(2011) (geog2D) to NAD83(2011) (geocentric) + 
Inverse of ITRF2014 to NAD83(2011) (1) + Inverse of ITRF2000 to ITRF2014 (1) + 
Conversion from ITRF2000 (geocentric) to ITRF2000 (geog2D), 0.01 m, USA - 
CONUS and Alaska; PRVI

PROJ string:
+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert 
+xy_in=deg +xy_out=rad +step +proj=cart +ellps=GRS80 +step +inv +proj=helmert 
+x=1.0053 +y=-1.9092 +z=-0.5416 +rx=0.0267814 +ry=-0.0004203 +rz=0.0109321 
+s=0.00037 +dx=0.0008 +dy=-0.0006 +dz=-0.0014 +drx=6.67e-05 +dry=-0.0007574 
+drz=-5.13e-05 +ds=-7.00000000000001e-05 +t_epoch=2010 
+convention=coordinate_frame +step +inv +proj=helmert +x=-0.0007 +y=-0.0012 
+z=0.0261 +rx=0 +ry=0 +rz=0 +s=-0.00212 +dx=-0.0001 +dy=-0.0001 +dz=0.0019 
+drx=0 +dry=0 +drz=0 +ds=-0.00011 +t_epoch=2010 +convention=position_vector 
+step +inv +proj=cart +ellps=GRS80 +step +proj=unitconvert +xy_in=rad 
+xy_out=deg +step +proj=axisswap +order=2,1


Even


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