@swissgeo/coordinates

Projection definitions and coordinate utilities for SWISSGEO projects, with utilities to set up an OpenLayers map in LV95.

Overview

This package provides a comprehensive set of tools for working with geographic coordinates and map extents, with a focus on Swiss coordinate systems (LV95, LV03) and standard systems (WGS84, Web Mercator).

Installation

npm install @swissgeo/coordinates

Note: This package has proj4 as a peer dependency.

Note: If you intend to use the OpenLayers utilities, you will also need to install ol (optional dependency).

Features

• Projection Definitions: Built-in support for:
  • LV95 (EPSG:2056) - Swiss CH1903+ / LV95
  • LV03 (EPSG:21781) - Swiss CH1903 / LV03
  • WGS84 (EPSG:4326) - World Geodetic System 1984
  • Web Mercator (EPSG:3857) - WGS 84 / Pseudo-Mercator
• Coordinate Utilities: Formatting, reprojection, rounding, and validation.
• Extent Utilities: Normalization, reprojection, intersection, and center calculation.
• OpenLayers Integration: Helper functions for OpenLayers in regard to Swiss projection systems (TileGrids, Views).

Usage

Basic Usage

The default export provides access to all coordinate systems and utility modules.

import { LV95, WGS84, coordinatesUtils } from '@swissgeo/coordinates'

// Reproject a coordinate
const pointLV95 = [2600000, 1200000]
const pointWGS84 = coordinatesUtils.reprojectAndRound(LV95, WGS84, pointLV95)

Projections and Constants

You can import specific coordinate systems and constants:

import { LV95, constants } from '@swissgeo/coordinates'

console.log(LV95.epsg) // "EPSG:2056"
console.log(constants.LV95_RESOLUTIONS) // Array of resolutions for LV95

Coordinate Utilities

import { coordinatesUtils } from '@swissgeo/coordinates'

// Format coordinates for display
const formatted = coordinatesUtils.toRoundedString([2600000, 1200000], 2)
// => "2'600'000.00, 1'200'000.00"

// Parse CRS string to CoordinateSystem object
const crs = coordinatesUtils.parseCRS('EPSG:2056')
// => LV95

Extent Utilities

import { extentUtils, LV95, WGS84 } from '@swissgeo/coordinates'

const extentLV95 = [2485000, 1075000, 2837000, 1296000]

// Reproject an extent
const extentWGS84 = extentUtils.projExtent(LV95, WGS84, extentLV95)

// Get center of an extent
const center = extentUtils.getExtentCenter(extentLV95)

OpenLayers Integration

The package provides specialized helpers for OpenLayers in @swissgeo/coordinates/ol.

import {registerProj4 } from '@swissgeo/coordinates'
import { getLV95ViewConfig, getLV95WMTSTileGrid } from '@swissgeo/coordinates/ol'
import TileLayer from 'ol/layer/Tile'
import Map from 'ol/Map'
import View from 'ol/View'
import XYZ from 'ol/source/XYZ'
import { register } from 'ol/proj/proj4'
import proj4 from 'proj4'

// 1. Register projections in proj4 and OpenLayers
registerProj4(proj4);
register(proj4);

// 2. Use helpers to create View and TileGrid
const map = new Map({
  target: 'map',
  view: new View({
    ...getLV95ViewConfig(),
    // any other view configuration
  }),
  layers: [
    new TileLayer({
      source: new XYZ({
        url: 'https://wmts.geo.admin.ch/1.0.0/ch.swisstopo.pixelkarte-farbe/default/current/2056/{z}/{x}/{y}.jpeg'
        projection: LV95.epsg,
        tileGrid: getLV95WMTSTileGrid()
      })
    })
  ]
})

License

BSD-3-Clause

Repository

https://github.com/geoadmin/web-mapviewer