proj4-fully-loaded

Proj4JS Projector Fully Loaded with Projections

install

npm install -S proj4-fully-loaded

motivation

One of the most popular questions I hear from users of georaster is how do I use a GeoTIFF that's in UTM or another projection not included in the default build of proj4. I've created this library, so users can use georaster and georaster-layer-for-leaflet without worrying about how to find and load the projection information for their data.

usage

Use it just like you would proj4, except you don't have to load your projection.

const proj4 = require("proj4-fully-loaded");

const pointIn4326 = [-85.3097, 35.0456];

// EPSG:32617 is automatically included in proj4-fully-loaded
const pointInUTM = proj4("EPSG:4326", "EPSG:32617").forward(pointIn4326);
// pointInUTM is [106823.88325412886, 3886600.558377227]

manual way

For your reference, here is the way to manually load the projection information without the proj4-fully-loaded library.

const proj4 = require("proj4");

// find and load projection specific definition
// taken from http://epsg.io/32617
proj4.defs("EPSG:32617", "+proj=utm +zone=17 +datum=WGS84 +units=m +no_defs");

const pointIn4326 = [-85.3097, 35.0456];

const pointInUTM = proj4("EPSG:4326", "EPSG:32617").forward(pointIn4326);
// pointInUTM is [106823.88325412886, 3886600.558377227]

what about file size?

One of the inevitable questions will be, "don't you increase your bundle size by loading all this projection information?" This is a very valid question. This library (as compared to vanilla proj4) should only increase your bundle size by about 175 Kilobytes. If you are creating a library or application that supports multiple projections, please consider using this library and evaluating if the trade off is worth it. If you are building something that supports just one specific projection, you probably want to save size and load projection information using the approach above.

support

If you have any questions or comments, please post an issue here or email me at daniel.j.dufour@gmail.com