European Datum 1950 | EPSG:4230 (ED50)

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Introduction

ED50 is a European geodetic datum established in 1950. It is based on the overall adjustment of the European triangulated network and adopts Clarke ellipsoid parameters. It is mainly used for topographic surveying, mapping and early geographic information system (GIS) applications in Europe.

Coordinate System Composition

1. Datum

• Based on the European terrain fitting, plate movement is not considered, and there is an offset of about 100 meters from the WGS84 datum.

2. Ellipsoid

• Clark 1880 (IGN variant)
  • Semi-major axis: 6,378,249.2 meters
  • Reciprocal of flattening: 293.46602

3. Coordinate representation

• Geographic coordinates: longitude and latitude (such as <font style="background-color:rgb(253, 253, 254);">3.14°E, 48.85°N</font>).
• Projection coordinates: commonly used UTM 31N (such as <font style="background-color:rgb(253, 253, 254);">(488500, 5412500)</font> meters).

4. Storage and declaration

• Vector data (Shapefile, GeoJSON) must contain<font style="background-color:rgb(253, 253, 254);">.prj</font> or <font style="background-color:rgb(253, 253, 254);">crs</font> declaration:

1

EPSG:4230

5. Differences from WGS84

• Seven-parameter conversion (translation, rotation, scaling) is required, with an error of about 100 meters.

Pros

1. **Historical data compatibility: **ED50 is the core benchmark of traditional European geodesy. A large number of historical maps, topographic maps and early surveying and mapping data are built based on this benchmark.
2. **Local accuracy advantage: **In central and western Europe (such as France, Spain, and parts of Italy), ED50 has high triangulation adjustment accuracy and is suitable for small-scale, high-precision surveying tasks.
3. **Technical heritage value: **As a milestone in the history of European geodesy, the data and methods of ED50 laid the foundation for subsequent benchmarks (such as ETRS89) and are of great significance to the study of historical geographical changes.

Cons

1. Large global positioning deviation: ED50 does not take into account plate movement, and its coordinates have significant deviations from modern benchmarks (such as WGS84, ETRS89), with an average deviation of hundreds of meters.
2. High conversion complexity: The conversion between ED50 and modern benchmarks requires Helmert seven parameters or complex grid models, which are cumbersome to calculate and easy to introduce errors.
3. Insufficient dynamics: It cannot reflect crustal movement (such as glacial isostatic adjustment, earthquake deformation), resulting in distortion of long-term observation data.

Application Scenario

It is suitable for the conversion of traditional geodetic and historical map data in central and western Europe, especially for scenarios that require compatibility with old European geographic data.

Example

1. ED50 ovierview.

2. ED50 and WGS84.

Related GIS Coordinate Systems

GDA2020

ED50

GCS

CGCS2000

References

1. https://en.wikipedia.org/wiki/ED50
2. https://epsg.io/4230
3. https://www.gim-international.com/content/article/european-datum-1950-a-history