Jochem Lesparre and Lennard Huisman�Kadaster, Netherlands Partnership Geodetic Infrastructure��Modernised transformation between�century old national CRS and ETRS89 ��Towards a State Plane Coordinate System 2025 Skopje (online)

National projected (state plane) CRS

Two ways to modernise the Coordinate Reference System (CRS):

​

1. Introduce a new, homogeneous national CRS

+ Easy for geodesists and professional surveyors

− Complex for end users of geo-data and surveyors from other fields

− Expensive and long transition period

​

• Modernise the transformation between existing national CRS and ETRS89

​

​

​

​

2

Netherlands’ national projected coordinates: RD

1888-1904 1^st-order triangulation

1898-1928 Densification triangulation

1930-2014 Maintenance of triangulation points

1960-1978 Revision of coordinates low-order points

3

Netherlands’ national projected coordinates: RD

1888-1904 1^st-order triangulation

1898-1928 Densification triangulation

1930-2014 Maintenance of triangulation points

1960-1978 Revision of coordinates low-order points

2000-now Redefined by GNSS + transformation

4

2014-2018 Project: Switch to ETRS89?

Motivation:

Official transformation in survey equipment and software

but 25 cm error in GIS software: transformation too “complex”

​

​

5

What projection of ETRS89?

• Users want a single projection (metres)
• INSPIRE recommended projections have larger scale error than RD

​

​

6

​

​

scale cm/km

New projection of ETRS89 for the Netherlands?

• Custom TM for the Netherlands similar scale error as RD
• New coordinates are confusing and even impossible for some users
• Transformation from RD to ETRS89 needed in GIS

to migrate old datasets to new projection

• New projection needed if RD is in GIS?

​

​

​

​

scale cm/km

7

The old transformation

3 steps:

• 7-parameter datum transformation
• Stereographic map projection
• Correction/distortion grid (25 cm)

​

8

The modernised transformation

​

2 steps:

• 7-parameter datum transformation
• Correction/distortion grid (25 cm)
• Stereographic map projection

9

datum transformation grid

Difference with old transformation

< 1 cm within administrative borders at sea level

​

​

​

10

Result

​

With the new transformation in EPSG, we can

continue to use RD as national projection next to

ETRS89, as everyone can transform back and forth

without losing accuracy!

​

​

​

​

​

• Unprojected ETRS89 for geodetic applications (ETRF2000 epoch 2010.50)
• National projected RD for surveying and geo-data (EPSG:28992)
• Free official transformation RD-ETRS89 available in surveying and GIS software

​

Conditions to keep old national CRS

• Transformation method complies with ISO model of EPSG
• Enough datapoints to estimate correction grid
• Spatially-correlated and smooth distortions
• Commonly supported projection with scale close to 1
• Good datum transformation (precision and size of rotation parameters)

12

Conclusions

• No new national CRS needed in the Netherlands now
• The datum transformation can accommodate new ETRFs (e.g. ETRF2020)
• Ready to switch to new projected CRS when needed

​

​

A new CRS could create more practical problems than it solves,

as many end users might keep using the old CRS

​

​

Questions?

​

​

​

​

​

​

​

​

​

​

​

rd@kadaster.nl