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I have a building shapefile in my country which, when imported is in CRS EPSG 4326 - WGS 84. I need to project this to typical latitude, longitude values (If my GIS knowledge is right, to EPSG 3857 - WGS 84)

The initial map is multiple times the Google map / Openstreet Map in extent.

I exported this as a TAB file with the 3857 CRS. Exported like this; export dialog box settings - default

When the layer gets imported to the map, it becomes the right dimensions. But it is now centered at the map (at latitude 0, longitude 0)

map moved to center

I need to move this to my country.

  • How do I do this movement? Is there a setting/tool or a straightforward method?
  • Am I right to assume the initial shapefile that I had, does not contain the coordinate data for it to be properly positioned in a lat, lon map?
  • If I am to offset this to my country, do I have to manually add the coordinate values to all polygons?

I am new to GIS, in fact it is not my field. I am using GIS tools to do some telecommunication analytics.

Vince
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Tharaka Devinda
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    Without providing your data, it's impossible to say if your initial shapefile contained the coordinate data correctly. The rest of your question seems to depend on this: so can you provide your data for testing? Are you aware of the difference between re-projecting and changing the layer CRS? See: https://gis.stackexchange.com/a/383437/88814 – Babel Jul 05 '21 at 13:00
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    While close to 0;0, it is more than 90m north of it, so it seems not related to having assigned a CRS vs projecting the data. – JGH Jul 05 '21 at 13:10
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    Web Mercator isn't "typical latitude, longitude values". Web Mercator uses units of meters (though they don't actually represent meters anywhere not on the Equator). EPSG 4326 uses degrees. If you specify the extents of the shapefile and the country it's supposed to be in, we might be able to help. – Vince Jul 05 '21 at 14:49
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    Note that EPSG 4326 IS the "typical" geographic coordinate system with latitude and longitude values expressed on the WGS84 ellipsoid while EPSG 3857 is a projected coordinate system with X an Y value expressed as meter (and also use the WGS84 ellipsoid)? Anyway even your data should initially display correctly regardless of their CRS, your problem is probably caused by data having the wrong CRS information to start with. I would suggest to try to assign (not re-projecting !) EPSG 4326 to your data and see if they display right – J.R Jul 05 '21 at 15:01

1 Answers1

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Your data is not in EPSG 4326 - WGS 84 originally.

If it was it would display correctly over your country before you try to reproject it.

It does have some coordinates because it displays.

But you need to figure our what projection the original data is in. Either from where you downloaded it (some metadata), or by trying out some projections until you find one where after applying it lines up with the map correctly.

HeikkiVesanto
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