EPSG:4671 — Voirol 1879
Voirol 1879 (EPSG:4671) — a Geographic (degrees) system on the clrk80ign datum, used in Algeria. Parameters, proj4, WKT, accuracy ±0.1 m, plus a free converter to WGS84…
At a glance
- EPSG
- 4671
- Name
- Voirol 1879
- Kind
- Geographic (degrees)
- Family
- Geographic (longitude/latitude)
- Ellipsoid
- clrk80ign
- Accuracy
- ±0.1 m (vs PROJ)
- Countries
- Algeria
Area of use
| West | -2.95° |
| South | 31.99° |
| East | 9.09° |
| North | 37.14° |
Projection parameters
| Projection | longlat |
| Ellipsoid | clrk80ign |
+proj=longlat +ellps=clrk80ign +no_defs
GEOGCS["GCS_Voirol 1879",DATUM["D_Clarke_1880_IGN",SPHEROID["Clarke_1880_IGN",6378249.2,293.4660212936269]],PRIMEM["Greenwich",0],UNIT["Degree",0.0174532925199433],AUTHORITY["EPSG","4671"]]
Sample conversion
Algeria capital: WGS84 3.05880, 36.75380 → EPSG:4671 3.0588000, 36.7538000
Values are within ±0.1 m at the test point.
About the Geographic (longitude/latitude) family
Voirol 1879 is a geographic coordinate system: positions are longitude and latitude in degrees on its reference ellipsoid, not metres on a plane. It is the datum layer that projected grids (UTM, national belts) are built upon.
Because it is unprojected, distances and areas cannot be measured directly from its degrees — convert to a metric projected system (or use a geodesic calculation) first. This page's converter does exactly that.
Related systems
- EPSG:4206 — Agadez
- EPSG:4304 — Voirol 1875
- EPSG:4307 — Nord Sahara 1959
- EPSG:10299 — RGSH2020
- EPSG:22229 — RGSH2020 / UTM zone 29N
- EPSG:22230 — RGSH2020 / UTM zone 30N
- EPSG:32629 — WGS 84 / UTM zone 29N
- EPSG:32630 — WGS 84 / UTM zone 30N
- EPSG:32631 — WGS 84 / UTM zone 31N
- EPSG:32632 — WGS 84 / UTM zone 32N
Useful links: Converter · Batch converter · File converter · Country page
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FAQ
- What is EPSG:4671?
- It is the coordinate system “Voirol 1879”, a Geographic (degrees) system in the Geographic (longitude/latitude) family, identified worldwide by the code EPSG:4671.
- What datum does it use, and how accurate is it?
- It is based on the clrk80ign ellipsoid with no default transform to WGS84 (ballpark). The residual at the test point is about ±0.1 m versus PROJ; for centimetre work use a geodetic adjustment service.
- Where is this system used?
- It is used in Algeria. This page shows its area of use as a coordinate rectangle above.
- How do I convert EPSG:4671 to WGS84?
- Use the free coordinate converter above (preloaded with this system) to convert to WGS84, UTM, or any other system, within a ±0.1 m residual.
You may also need: Arab-world coordinate converter · Surveying file format converter · Batch coordinate file converter