URIProj

A TypeScript wrapper for loading remote CRS WKT definitions and extends the original uriproj by adding support for URNs and shorthand prefixes, making it easier to work with different CRS formats.

Features

• Supports specifying OGC URNs, URIs and : shorthands
• Uses OGC WKT2 definitions eliminating need for NADGRID TIFF files
• Caches definitions

Installation

npm install @murithigeo/uriproj

Quick Start

import { uriproj, load, fromAuthCode, toURI } from "@murithigeo/uriproj";

// Project coordinates from EPSG:4326 to OGC:CRS84
const converter = await uriproj({
  from: "EPSG:4326",
  to: "OGC:CRS84",
});

const projected = converter.forward({ x: -90, y: -180 });
console.log(projected); // { x: -180, y: -90 }

API Documentation

Formats

URIProj supports three CRS identifier formats:

1. Authority:Code (shorthand): EPSG:4326, OGC:CRS84
2. URI: http://www.opengis.net/def/crs/EPSG/0/4326
3. URN: urn:ogc:def:crs:EPSG:0:4326

The fromURI, fromURN and fromAuthCode functions allow conversions to other formats

The toURI allows conversions from an unknown string to an absolute URI

Loading a remote WKT definition

Loads a CRS definition from spatialreference.org and caches it locally. Automatically registers the definition with proj4. Accepts any supported CRS format.

import { load } from "@murithigeo/uriproj";

let wkt = await load("EPSG:4326");
wkt = await load("urn:ogc:def:crs:OGC:1.3:CRS84");
wkt = await load("http://www.opengis.net/def/crs/EPSG/0/4326");

console.log(wkt);

Retrieving a cached definition

Retrieve a cached CRS definition.

import { get } from "@murithigeo/uriproj";

const cached = get("http://www.opengis.net/def/crs/EPSG/0/4326");
if (cached) {
  console.log("CRS definition is cached:", cached);
}

Getting the Converter function

const converter = await uriproj({
  from: "OGC:CRS84", // If undefined, defaults to EPSG:4326
  to: "EPSG:32737",
});

Re-exported from proj4

Both proj4 and the Converter type are re-exported for convenience:

import { proj4, type Converter } from "@murithigeo/uriproj";

// Use proj4 directly if needed
proj4.defs("EPSG:4326");