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Question

DGN V7 arc features not converting when switching coordinate systems


louis_boekhoudt
Contributor
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Hi, I am transforming microstation files (DGN V7) from an local (ADN1953) coordinate system to microstation files (dgn V7) another local coordinate system (AGN2005). The arc features are not going over.

3 replies

daveatsafe
Safer
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  • Safer
  • July 24, 2018

Hi @louis_boekhoudt,

FME attempts to retain arcs as arcs when reprojecting data, but this is not always possible. In this case, FME will stroke the arc into a linestring, to ensure that its path in the new coordinate system is correct.

Without seeing your log file, I can't be sure, but what is likely happening is that the arc has been stroked to linestrings, but the igds_type is still set to igds_arc, causing the writer to skip the feature.

If you do the conversion in FME Workbench, you can use an AttributeRemover to remove the igds_type attribute, forcing the writer to figure out what the type is from the actual geometry.


louis_boekhoudt
Contributor
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HI.

 

case nr:138241

 

I did reload the FME desktop version 2017.1 and rerun the conversion it went perfect.

 

So I think there must be something wrong in this case with the FME dektop 2018.1.

 

Louis


daveatsafe
Safer
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  • Safer
  • July 26, 2018

Hi @louis_boekhoudt,

Thank you for sending us the repro case.

We introduced 3D arcs as a new geometry in FME 2018. We do seem to have a few issues writing these new arcs to Microstation DGNv7.

I have created problem reports for our development team, and will notify you as soon as they are fixed.

There is a workaround to avoid the missing arcs:

- Instead of setting the source and destination coordinate systems, use a CsmapReprojector transformer to do the reprojection.

- Before the reprojector, use an AttributeCopier to copy the attribute igds_type to _type.

- After the reprojector, use another AttributeCopier to copy _type back to igds_type.

I'm sorry, but there is no workaround right now for the bad arcs within a polygon path, unless you use an Arcstroker to stroke the arcs to linestrings before reprojecting.


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