swissgrid_reframe

swissgrid_reframe

JavaScript library for transforming coordinates between the Swiss projected coordinate systems (LV03 and LV95).

LV03 is the old reference frame derived from triangulation and was used in Switzerland until 2016. LV03 coordinates are by convention designated by the letters y for the easting and x for the northing, with origin at y = 600 000 m / x = 200 000 m. The origin is not at 0 / 0 to avoid confusion between easting and northing, this is sometimes called "false easting" and "false northing".

LV95 is the new reference frame derived from GNSS surveying and is used in Switzerland since 2016. LV95 coordinates are by convention designated by the letters E for the easting and N for the northing, with origin at E = 2 600 000 m / N = 1 200 000 m. This still avoids confusion between easting and northing, and the additional 2 000 000 m / 1 000 000 m offset also avoids confusion with LV03.

Due to local distortions of the LV03 reference frame, coordinates in LV03 and LV95 can differ by up to 1.6 meters. Swisstopo provides a dataset of triangles (CHENyx06) for local affine transformations to model these distortions which the swissgrid_reframe library uses to transform between LV03 and LV95.

See Swisstopo reference document about Swiss projected coordinate systems for more information.

Usage

import { lv03_to_lv95, lv95_to_lv03 } from "swissgrid_reframe";

lv03_to_lv95([722758.81, 87649.67]); 
// Result: [2722759.06, 1087648.19]

lv95_to_lv03([2722759.06, 1087648.19]);
// Result: [722758.81, 87649.67]

License

See LICENSE.txt.

See also

Similar software

The following software also uses CHENyx06 to transform between LV03 and LV95:

• GeoSuite: Windows software
• REFRAME DLL / JAR: .NET / Java libraries
• REFRAME web service: Based on REFRAME DLL, see example calls below
  • https://geodesy.geo.admin.ch/reframe/lv03tolv95?easting=722758.81&northing=87649.67
  • https://geodesy.geo.admin.ch/reframe/lv95tolv03?easting=2722759.06&northing=1087648.19

Swisstopo also provides an NTv2 grid for transformations between LV03 and LV95:

• Swisstopo NTv2 grid

Note that this has slightly lower precision than the CHENyx06-based transformations.

References

• Swisstopo reference document about Swiss projected coordinate systems
• Usage of PROJ at swisstopo
• Neue Koordinaten für die Schweiz - Der Bezugsrahmen LV95