Transformations

This repository contains a modified proj.db that implements the following transformations according to the recommendations of the NSGI (see image below).

1. SQL which adds to the PROJ proj.db:

   • added NSGI to authority references
   • added extents of NSGI transformations
   • added additional NL datum (AGRS.NL)
   • added additional NL CRSs
   • added additional NSGI transformations

2. A Dockerfile with PROJ configured to use this NSGI authority as a base

These will form the base for the transformations that are defined or recommended by NSGI (Nederlandse Samenwerkingsverband Geodetische Infrastructuur). In the future additional transformations might be added to this repository.

⚠️ this repository contains 2 proj.db. The first (the default) proj.db has the sql scripts nl_nsgi_00... till ns_nsgi_50... applied. The second proj.time.dependent.transformations.db has the sql script 'nl_nsgi_60_time_dependent_transformations.sql' applied for adding time dependent transformations. For this second proj.db, a input epoch should be provided (when applicable), to prevent the use of the default reference epoch of the transformation. When one wants to use this second proj.db this can be done in the following ways.

Through a move command

mv proj.db proj.db.bak
mv proj.time.dependent.transformations.db proj.db

or through the creating of a symbolic link

ln -s proj.time.dependent.transformations.db proj.db

Docker

The Docker image is intended to be used as a base image, for applications that layer on top of PROJ; for instance use it with pyproj.

Build

docker build -t ghcr.io/geodetischeinfrastructuur/transformations:1.1.0 .

Run

To start an interactive terminal inside the container run:

docker run -it --rm --name nsgi-proj ghcr.io/geodetischeinfrastructuur/transformations:1.1.0

To invoke projinfo from your current terminal sessions run:

docker run --rm --name nsgi-proj ghcr.io/geodetischeinfrastructuur/transformations:1.1.0 projinfo

Test

To verify if the NSGI transformation EPSG:7931 -> EPSG:7415 works as expected, run the following in a terminal:

docker build -f validate/Dockerfile -t geodetischeinfrastructuur/pyproj:3.6.1 .
docker run --rm -it geodetischeinfrastructuur/pyproj:3.6.1 python

Then run the following Python code:

from pyproj import transformer
etrf = transformer.TransformerGroup("EPSG:7931", "EPSG:7415")
"{0[0]:.4f} {0[1]:.4f} {0[2]:.4f}".format(etrf.transformers[0].transform(52.115330444, 7.684748554, 41.4160))

Alternatively the following cs2cs cmd can be used:

cs2cs -f "%.4f" EPSG:7931 EPSG:7415 <<< "52.115330444 7.684748554 41.4160"

Both should result in the following output: '312352.6004 461058.5812 -2.5206'

Validation

Running the full validation file can be done by running the following docker run cmd.

docker run -d --rm -v `pwd`/validate:/validate geodetischeinfrastructuur/pyproj:3.6.1 python ./validate/validate.py ./validate/Z001_ETRS89andRDNAP.txt ./validate/validation-output.csv

Or by running the python script directly.

cd validate
python validate.py Z001_ETRS89andRDNAP.txt validation-output.csv

This should output a validate/validation-output.csv file containing the results. When correct the result would show no (or minimal) deviation.

LICENSE

The SQL used in this repository is licensed under a CC-BY license.

All other code in this repository is licensed under the MIT license.