Defining and changing unknown CRS into WGS84

Question

I came across a shapefile (no information available about the original CRS) with some unknown Reference System (City of Stuttgart in Germany). Example of coordinates looks like 3465878, 5482952. I assume it is lat/lon.

How can I change the CRS to the decimal system of WGS84 with QGIS 3?

Is it possible to overlay it to another shapefile with the borders and match the CRS?

You need to determine the original CRS to be able to apply the correct transformation to WGS84. see this to learn how :https://gis.stackexchange.com/questions/7839/identifying-coordinate-system-of-shapefile-when-unknown — J.R, Oct 01 '19 at 13:19
Have you tried one of Zones from DHDN / 3-degree Gauß-Krüger, or one Zone from ETRS89 UTM North? — Taras, Oct 01 '19 at 13:25
3465878, 5482952 (I assume lat/lon)) Obviously not lat long otherwise you'd expect lat values +/- 90 degrees and long +/- 180 degrees but your values are in the 100,000's so more likely to be units of metres — nmtoken, Oct 01 '19 at 13:34

Taras · Answer 1 · 2019-10-10T07:04:20.757

Step 1. Defining unknown CRS

I would suggest double-checking if suddenly there is a prj-file, placed in the shapefile location.

If not, you can try using projfinder. For instance, when one tried it with provided coordinates (3465878, 5482952)

There are two options:

EPSG:31467 Name:DHDN / 3-degree Gauss-Kruger zone 3, as was mentioned by @MrXsquared
EPSG:31463 Name:DHDN / 3-degree Gauss zone 3 (deprecated)

I would proceed with EPSG:31467 because EPSG:31463 is not maintained anymore.

EPSG:31467

DHDN / 3-degree Gauss-Kruger Zone 3

WGS84 Bounds: 7.5000, 47.2700, 10.5000, 55.0600
Projected Bounds: 3386564.9400, 5237917.9109, 3613579.2251, 6104500.7393
Scope: Large and medium scale topographic mapping and engineering survey, cadastral survey
Last Revised: Sept. 24, 2008
Area: Germany - 7.5°E to 10.5°E

Step 2. Changing unknown CRS into WGS84

It is already a well-known topic in the GIS domain. So, I would highly suggest to simply searching it online.

There are several references that I may point out:

Step 3. Overlaying with another shapefile

The vital trick is that all of your shapefiles that have to be overlapped must match the same CRS.

Very useful website. Will bookmark it. – MrXsquared Oct 01 '19 at 14:57 — MrXsquared, Oct 01 '19 at 14:57
Yeap, Mr. @spacedman first demonstrated it to me – Taras Oct 01 '19 at 14:59 — Taras, Oct 01 '19 at 14:59

score 3 · Answer 2 · answered Oct 01 '19 at 14:45

I am pretty sure this is GK3 (EPSG:31467).

Go to layer properties --> Source and set source CRS to EPSG:31467

Then do the transformation (Export as...) to WGS84.

If everything is located perfectly, you are good to go. (If not, I was wrong about the CRS...)

Defining and changing unknown CRS into WGS84

2 Answers2

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