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Issue reprojecting Shapefiles from EPSG:5650 to EPSG:25832 (ThinkGeo 14.2)

#1

Hello,

I am working with ThinkGeo UI (v14.2) and I’m facing issues reprojecting Shapefiles from ETRS89 / UTM zone 33N (zE-N) ( EPSG:5650 ) to EPSG:25832 .

I have tried using both GdalProjectionConverter and ProjectionConverter , but without success. The data is either not displayed correctly or the transformation does not seem to take effect.

My questions:

  1. Are there known issues with the EPSG:5650 definition in the version 14.2?
  2. Is there a specific requirement for the ExternalProjectionParameters string when dealing with the “zE-N” variant of UTM?
  3. Should I prefer GdalProjectionConverter over the standard ProjectionConverter for these specific European CRS?

Any suggestions or a small code example would be greatly appreciated.

Regards,
Torsten

#2

Hi Juergen,

We couldn’t recreate the issue. Here is our test code using v14.2.1:

using System.Globalization;
using ThinkGeo.Core;

const int SourceEpsg = 5650; // ETRS89 / UTM zone 33N (zE-N)
const int TargetEpsg = 25832; // ETRS89 / UTM zone 32N

// EPSG:5650 uses a zone-prefixed easting (33,500,000 m for zone 33).
var sourcePoint = new PointShape(33500000, 4649776);

GdalConfig.ConfigureGdal();
using var gdalConverter = new GdalProjectionConverter(SourceEpsg, TargetEpsg);
gdalConverter.Open();
var gdalPoint = gdalConverter.ConvertToExternalProjection(sourcePoint) as PointShape;
gdalConverter.Close();

var corePoint = ProjectionConverter.Convert(SourceEpsg, TargetEpsg, sourcePoint) as PointShape;

Console.WriteLine($"Source EPSG:{SourceEpsg} (E,N): {sourcePoint.X.ToString(CultureInfo.InvariantCulture)}, {sourcePoint.Y.ToString(CultureInfo.InvariantCulture)}");
Console.WriteLine($"GdalProjectionConverter -> EPSG:{TargetEpsg} (E,N): {gdalPoint?.X.ToString(CultureInfo.InvariantCulture)}, {gdalPoint?.Y.ToString(CultureInfo.InvariantCulture)}");
Console.WriteLine($"ProjectionConverter -> EPSG:{TargetEpsg} (E,N): {corePoint?.X.ToString(CultureInfo.InvariantCulture)}, {corePoint?.Y.ToString(CultureInfo.InvariantCulture)}");

the output:

image
image1175×97 7.85 KB

which aligns well with the expected result:

So can you let me know how to recreate the issue?

And for your questions:

  1. there’s no known issues, nor specific requirement about epsg: 5650. Check out the changelog here: https://docs.thinkgeo.com/products/desktop-maps/changelog/ to find the projection related updates.
  2. I would recommend GdalProjectionConverter, which is more up to date, if you can.

Thanks,
Ben

#3

Hi Ben,

Thanks for your answer. To clarify my previous post: I am using ThinkGeo Version 14.4.0 , specifically the ThinkGeo.Core.Gdal package.

I have attached one of the shapefiles I am working with.

I’ve encountered two main issues:

  1. When I load this file into the “HowDoI” sample without using a ProjectionConverter , nothing is displayed on the map.
  2. When I try to use the GdalProjectionConverter (Internal: 5650 , External: 25832 ) and call GetBoundingBox() , it returns an invalid result (or an invalid feature).

Could you please take a look at the attached file and provide some suggestions on how to handle this projection correctly?

Best regards,
TorstenTestfelder.zip (12.8 KB)

#4

Hi Juergen,

It’s recreated and fixed in the latest beta087, thanks for the demo! Let us know if you see any new issues.

Thanks,
Ben