Transform translators
A transform translator converts a value from one representation into another without changing what it means. Today the family is coordinate projections: taking the global WGS84 position a device reports and expressing it in a national or local grid instead.
They are chained, running on top of whatever translator produced the position.
Why project coordinates
A GNSS device reports WGS84, degrees of latitude and longitude on a global ellipsoid. Swedish municipalities, utilities and surveyors do not work in that. Their maps, property boundaries, pipe networks and case systems are held in SWEREF 99, a flat grid in metres.
Handing a WGS84 position to those systems means someone converts it, every time, in whatever tool is nearest, and small differences in method turn into positions that disagree by metres. Doing it in a translator means the projected coordinate is a stored field on the device, computed the same way for every device, ready for the GIS system to consume directly.
Because it is a normal field, everything else in Yggio works on it unchanged: views, exports, reports and the API.
The translators
| Translator | Projects onto | EPSG | Zone |
|---|---|---|---|
transform-wgs84-to-sweref-99-tm | SWEREF 99 TM | EPSG:3006 | Sweden's national grid, one zone for the whole country. Central meridian 15°E, scale factor 0.9996 |
transform-wgs84-to-sweref-99-12-00 | SWEREF 99 12 00 | EPSG:3007 | Local zone, central meridian 12°E |
transform-wgs84-to-sweref-99-13-30 | SWEREF 99 13 30 | EPSG:3008 | Local zone, central meridian 13.5°E |
Each writes the projected coordinate to location and keeps prevPosition, the previous position, alongside it.
Choosing a zone
Use SWEREF 99 TM unless you have been told otherwise. It covers all of Sweden in a single zone and is what national datasets and most map services expect.
The local zones exist because a single national projection distorts distances the further you get from its central meridian. Municipalities and utilities that survey their own area to the centimetre often keep their data in the local zone nearest to them, and if your data has to line up with theirs, match what they use. The number in the name is the central meridian: 12 00 for 12°E, 13 30 for 13.5°E.
Getting this wrong does not produce an obvious error. It produces coordinates that look plausible and land in the wrong place, so confirm the zone with whoever owns the receiving system.
Parameters
None. The projection is fully determined by the target zone, which is fixed by the choice of translator, so there is nothing to configure. Add the one matching the grid your data has to line up with.
For the full A–Z index of every translator, see the translators overview.