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Coordinate system handling differences between FME 2020 and FME 2024 (DGNV8 Reader)

  • July 3, 2026
  • 4 replies
  • 95 views

helmoetz
Supporter
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Hello,

We are currently upgrading an FME-based application for one of our customers from FME 2020 to FME 2024, and we have encountered an issue that appears to be related to coordinate system handling.

The application uses FME to convert a set of DGNV8 drawings into an MS SQL Server database. For some drawings, we observe a positional shift of approximately 10 centimeters (a few decimeters at most) after processing.

In the DGNV8 Reader, the Coordinate System parameter in the Navigator window is set to "".

When inspecting the source datasets with FME Data Inspector in FME 2020, all drawings are reported as having an Unknown Coordinate System, regardless of which file is opened.

However, in FME 2024, we see different behavior:

  • For some drawings, Data Inspector reports the coordinate system as EPSG:28992.
  • For other drawings, it reports NationalRD-NL.

The drawings belonging to the latter group appear to be shifted relative to the other drawings.

My questions are:

  1. Is this behavior related to differences in coordinate system support and handling between FME 2020 and FME 2024?
  2. What would be the recommended approach to prevent these positional shifts?
  3. Would it make sense to explicitly set the DGNV8 Reader's Coordinate System parameter to EPSG:28992? If so, could this implicitly trigger a coordinate transformation during the reading process?
  4. What exactly is the NationalRD-NL coordinate system? I am not familiar with it. Based on the parameters I have checked, it appears to differ from the commonly used Dutch coordinate system EPSG:28992 (Amersfoort / RD New).

Any insights or recommendations would be greatly appreciated.

Thank you in advance.

4 replies

daveatsafe
Safer
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  • Safer
  • July 7, 2026

Hi ​@helmoetz,

We added coordinate system reading to the Microstation reader in FME 2023.1. If there is a coordinate system set in the DGN file, newer versions of FME will read it and assign it to the incoming features.

If a feature with no coordinate system is sent through a Reprojector that only has an output coordinate system set, the feature is not reprojected, but is tagged with the output coordinate system. If a feature with a coordinate system set is sent through that same Reprojector, it is reprojected to the output coordinate system.

The coordinate systems NationalRD-NL and EPSG:28992 use the same projection parameters, but are based on a different datum definitions, that have slightly different transformations to WGS84. This will cause a datum transformation when reprojecting from one to the other in the Reprojector in the workspace.

The simplest way to restore the behavior seen in FME 2020 is to replace the Reprojector with a CoordinateSystemSetter to set the coordinate system to EPSG:28992. This will simply set the coordinate system without doing any reprojection, whether there is an existing coordinate system or not. Alternatively, you could set the Coordinate System in the DGN reader to EPSG:28992 to override coordinate system read from the file.

 


helmoetz
Supporter
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  • Author
  • Supporter
  • July 8, 2026

Thanks for your anwer ​@daveatsafe, this indeed is what we are going to apply. 


geomancer
Evangelist
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  • Evangelist
  • July 8, 2026

NationalRD-NL may well be Oracle SRID 90112


george.schenk
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NationalRD-NL is not a CRS as far as I can tell. I am also working on that project and these are the details of that projection:

FME Configuration: Source coordinate system for reader DGNV8_1[DGNV8] set to `NationalRD-NL' as read from input data
Coordinate System `NationalRD-NL' parameters: CS_NAME=`NationalRD-NL' DESC_NM=`National RD/NAP -- References DutchRD rather than Amersfoort' DT_NAME=`DutchRD' GROUP=`LEGACY' MAP_SCL=`1' MAX_LAT=`89.99972220000001' MAX_LNG=`95.3876388888889' MIN_LAT=`-37.84383944444445' MIN_LNG=`-84.6123611111111' ORG_LAT=`52.15616055555555' ORG_LNG=`5.387638888888889' PROJ=`OSTERO' QUAD=`1' SCL_RED=`0.9999079' SOURCE=`Active GPS Reference System for the Netherlands (AGRS.NL)' UNIT=`METER' X_OFF=`155000' Y_OFF=`463000' ZERO_X=`0.001' ZERO_Y=`0.001'

This is what  AGRS.NL points to:

https://gnss1.tudelft.nl/dpga/

It is part of the GNSS infrastructure in the Netherlands.