Importing points in Lat-Long ITRF2000

[Anonymous]

Hi,

I've been receiving CSV in Lat-long in ITRF2000 lately. I've been able to create a format file for importing in Lat-Long WSG84 that works well, but the ITRF2000 is not in the list of choices for the coordinate zone transformation. I really need the ITRF2000 because there is an approx 1.3m gap in X-Y between both systems.
Is there a way I can import in the ITRF2000 system?

Thanks,

[Pointdump]

Julie,
Welcome to the Autodesk Forums.
More information please. I've never seen data in ITRF2000. Where did your data come from? ITRF2000 is neither a Projected(length units on flat plane) nor a Geographic(degree units) Coordinate System.

Dave

[rl_jackson]

Glad you popped in on this @Pointdump I did a little research and it's not a current datum and almost seems astrologically (could be wrong). Also it's not the most current datum as they have updated with NGS and such. I think Wikipedia have a 2014 or 16. It also deals with tectonic plate shifts. Way above my head

[ChicagoLooper]

Only location I can think of that may use an ITRF projection is Japan but I don't think the OP's points are in that country. Or are they?

[Pointdump]

Hi Rick,
From the attached PDF:
These Earth Centered, Earth Fixed ECEF coordinates are the ones used by most
satellites systems to designate an earth position. This is done because it gives precise values
without having to choose a specific ellipsoid. Only the center of the earth and the orientation of
the axis is needed. To convert to angular coordinates, more information is needed. Some high
precision applications remain in ECEF to avoid additional error. High precision geodetic bench
marks have both angular and ECEF coordinates recorded in the data bases.
C. Terrestrial Reference Frames
At the highest accuracy, geodesy is done in a ECEF coordinate system. Different
organizations have defined a series of these over the last few decades. They are defined by
specifying the locations of a small set of reference bench marks. These definitions are in ECEF.
The idealized system is called a reference frame. The points used in practice, are called a
“realization” of that frame.
An ECEF system is essentially a Cartesian (x-y-z) system. In order to obtain latitude,
longitude and height, an ellipsoid model must be added. Some reference frames have ellipsoids
specified, some do not.
The official US Department of Defense (DoD) system is called World Geodetic
System 84 (WGS84). The Department of Commerce (DoC), though the National Geodetic
Survey (NGS), produces frames that cover the US and its possessions. Both the DoD and DoC
systems are in very close agreement with the best international systems.

And when you get an OPUS Report, the XYZ is usually unnoticed because we're after Lats & Longs or State Plane:

REF FRAME: NAD_83(2011)(EPOCH:2010.0000) IGS08 (EPOCH:2015.8587)

X: -2172347.946(m) 0.009(m) -2172348.790(m) 0.009(m)
Y: -4759571.097(m) 0.003(m) -4759569.765(m) 0.003(m)
Z: 3636193.122(m) 0.002(m) 3636193.001(m) 0.002(m)

LAT: 34 58 48.38540 0.000(m) 34 58 48.39820 0.000(m)
E LON: 245 28 2.09979 0.009(m) 245 28 2.04771 0.009(m)
W LON: 114 31 57.90021 0.009(m) 114 31 57.95229 0.009(m)
EL HGT: 234.164(m) 0.003(m) 233.389(m) 0.003(m)
ORTHO HGT: 264.676(m) 0.017(m) [NAVD88 (Computed using GEOID12B)]

UTM COORDINATES STATE PLANE COORDINATES
UTM (Zone 11) SPC (0203 AZ W)
Northing (Y) [meters] 3873618.012 441662.105
Easting (X) [meters] 725219.163 141890.887
Convergence [degrees] 1.41504978 -0.44876334
Point Scale 1.00022519 0.99999626
Combined Factor 1.00018843 0.99995951

Dave

[Pointdump]

Julie,
Getting back to your post:
"...ITRF2000 is not in the list of choices for the coordinate zone transformation."
I honestly don't know if C3D can transform >>>ITRF2000<<< to WGS84.
"Is there a way I can import in the ITRF2000 system?"
No way I can think of. You might need to use a 3rd party conversion.
Dave

[ChicagoLooper]

How did you create a 'file format for importing in Lat-Long WGS84?' How you answer this question could be the key in eliminating that 1.3m gap.

Lat-Long WGS84 is a global coordinate system that covers all of Planet Earth. If your ITRF coordinates fall on earth, then those ITRFs will invariably overlap with their LL84 counterparts. If there's a 1.3m gap I'm guessing it's due to the precision of your Lat-Long coordinates. How many decimal places are in your Lat-Longs. If they're in decimal degrees, do you have a minimum of 6 decimals? If they're DMS, do you have 2, 3 or 4 decimals in the seconds? Can you increase the precision of your Lat-Longs?

The more decimal places you have in your Lat-Longs the more accurate your points. BTW, do your coordinates land in Japan?

[jhill]

What's your required precision?

"In absolute positioning, the frame WGS84 (G1150) is materialized not by the coordinates
of marks on the surface of the Earth - as the NAD83 (CORS96) is - but by the
coordinates of points in space, namely, the 3-D location of the GPS satellites (given by
their precise or broadcast satellite ephemerides). Recent investigations [True, 2004] have
shown that for all practical purpose, the WGS84 (G1150) frame is identical to the
International Terrestrial Reference Frame of year 2000 (ITRF2000). Thus, except for
very accurate geophysical calculations (crustal dynamics; tectonic strain determination,
etc.), the WGS84 (G1150) is supposed to be aligned with the ITRF2000. In another
words, both have the same origin, orientation, and scale."

https://www.ngs.noaa.gov/CORS/Articles/WGS84NAD83.pdf

Transformation Details

NAME: WGS 84 (G1150) to ITRF2000 (1)

CODE: 7670

TRANSFORMATION VERSION: NGA-Wld 2001.0

TRANSFORMATION VARIANT: 1

ACCURACY: 0.02

AREA OF USE: World

SOURCE CRS: WGS 84 (G1150)

TARGET CRS: ITRF2000

TRANSFORMATION PARAMETERS: Parameter Value / File Ref Sign Reversible Unit X-axis translation 0 YES metre Y-axis translation 0 YES metre Z-axis translation 0 YES metre X-axis rotation 0 YES arc-second Y-axis rotation 0 YES arc-second Z-axis rotation 0 YES arc-second Scale difference 0 YES parts per million

https://georepository.com/transformation_7670/WGS-84-G1150-to-ITRF2000-1.html

You could also use a 3rd party translator:

https://mygeodata.cloud/cs2cs/

I would recommend including a known point to check the conversion.