International Terrestrial Reference Frame (ITRF) Matlab Toolbox

Version 1.2 (26 May 2025).

Coordinate transformations between different ITRS and ETRS89 realizations.

Synopsis:

crdvelout=itrf2itrf(crdvelin,from,to,yearin,yearout)   
crdout=itrf2itrf(crdin,from,to,yearin)  

Functions

Main functions:

itrf2itrf  - Transform coordinates/velocities between various ITRF's and ETRF2000, ETRF2014 and ETRF2020.  
pmmvel     - Get velocity from Plate Motion Model parameters.  

Other functions:

itrftp     - Get ITRF transformation parameters at a certain epoch  
itrftables - Print table with transformation parameters between ITRF's.    
itrf2etrf  - Transform coordinates/velocities between ITRFyy and ETRFyy.  

Support functions:

itrftpdef  - Define ITRF transformation parameters   
etrftpdef  - Define ETRF transformation parameters   
pmmpar     - Define Plate Motion Model parameters.     
dijkstra   - Find shortest path in a graph using Dijkstra's algorithm  
trafo3d    - 3D similarity transformation with 7 or 14 parameters  

Demo/test functions:

testitrf   - Test itrf2itrf using actual ITRF coordinates  
testpmm    - Test Plate Model Motion (PMM) functions  

Notes:

(1) itrf2itrf supports also transformations between ITRFyy and ETRF2000, ETRF2014 and ETRF2020.

(2) itrf2etrf only supports transformations between ITRFyy and ETRFyy, or vice versa, for the same year.

crdvelout=itrf2etrf(crdvelin,from,to,yearin,yearout)  
crdout=itrf2etrf(crdin,from,to,yearin)  

itrf2etrs is only useful for legacy ETRF. For operations involving ETRF2000, ETRF2014 and ETRF2020 you are better off with itrf2itrf.
To preform transformations between legacy ETRF split the transform in two steps, e.g.

        ITRFxx -> ETRFxx         itrf2etrf  
        ETRFxx -> ITRFxx         itrf2etrf  
        ITRFxx -> ETRFyy  :  
            ITRFxx -> ITRFyy     itrf2itrf  
            ITRFyy -> ETRFyy     itrf2etrf  
        ETRFxx -> ITRFyy  :  
            ETRFxx -> ITRFxx     itrf2etrf  
            ITRFxx -> ITRFyy     itrf2itrf  
        ETRFxx -> ETRFyy  :  
            ETRFxx -> ITRFxx     itrf2etrf  
            ITRFxx -> ITRFyy     itrf2itrf  
            ITRFyy -> ETRFyy     itrf2etrf  

(3) Dijkstra's algorithm to find the shortest path is used to construct all possible combinations of transformations.

Examples:

crdvelout=itrf2itrf(  ...  
  [  3899225.258   396731.815  5015078.341    -.0130    .0158    .0092 ; ...  
     3812141.404   395731.729  4995987.219     .0004   -.0013    .0002 ],...   
  'ITRF2005','ITRF2000',2008.4,2000.0)  

crdout=itrf2itrf(  ...  
  [  3899225.258   396731.815  5015078.341  ; ...  
     3812141.404   395731.729  4995987.219  ],...   
  'ITRF2005','ITRF2000',2008.4)  

crdvelout=itrf2itrf(  ...  
  [3924687.552  301132.856  5001910.904 -.0150 .0164 .0070], ...  
  'ITRF2000','ETRF2000',1997.0,1989.0)  

The Matlab functions in this package are free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation http://www.gnu.org/licenses/.

This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

(c) Hans van der Marel, Delft University of Technology, 2012-2025.