🇺🇦 "Leaflet was created 11 years ago by Vladimir Agafonkin, an Ukrainian citizen living in Kyiv." - (LeafletJS)

georaster-layer-for-leaflet

Display GeoTIFFs and soon other types of rasters on your Leaflet Map

Install

npm install georaster-layer-for-leaflet

GeoRaster Prerequisite

GeoRasterLayer requires that input be first converted into GeoRaster format. You can install GeoRaster with the following command:

npm install georaster

Load Package via Script Tag

<script src="https://unpkg.com/georaster-layer-for-leaflet/dist/georaster-layer-for-leaflet.min.js">

Usage

new GeoRasterLayer({ georaster }).addTo(map);

Demos

Why

Support for nearly all projections, thanks to proj4-fully-loaded and epsg.io
Super faster rendering thanks to a simple nearest neighbor interpolation
Use of web workers means seamless integration that doesn't block main thread
Loads large geotiffs greater than a hundred megabytes
Supports custom rendering including custom colors, directional arrows, and context drawing
Doesn't depend on WebGL
Mask data inside or outside a given geometry

The GeoRasterLayer Class

A custom class for rendering GeoTIFF's (including COG's) on a leaflet map. The layer extends L.GridLayer, see the docs for inherited options and methods.

Usage Example

Source Code: https://github.com/GeoTIFF/georaster-layer-for-leaflet-example/blob/master/main.js

var parse_georaster = require("georaster");

var GeoRasterLayer = require("georaster-layer-for-leaflet");
// or: import GeoRasterLayer from "georaster-layer-for-leaflet";

// initalize leaflet map
var map = L.map('map').setView([0, 0], 5);

// add OpenStreetMap basemap
L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
    attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
}).addTo(map);

var url_to_geotiff_file = "example_4326.tif";

fetch(url_to_geotiff_file)
  .then(response => response.arrayBuffer())
  .then(arrayBuffer => {
    parse_georaster(arrayBuffer).then(georaster => {
      console.log("georaster:", georaster);

      /*
          GeoRasterLayer is an extension of GridLayer,
          which means can use GridLayer options like opacity.

          Just make sure to include the georaster option!

          Optionally set the pixelValuesToColorFn function option to customize
          how values for a pixel are translated to a color.

          https://leafletjs.com/reference.html#gridlayer
      */
      var layer = new GeoRasterLayer({
          georaster: georaster,
          opacity: 0.7,
          pixelValuesToColorFn: values => values[0] === 42 ? '#ffffff' : '#000000',
          resolution: 64 // optional parameter for adjusting display resolution
      });
      layer.addTo(map);

      map.fitBounds(layer.getBounds());

  });
});

Options for GeoRasterLayer

The layer extends L.GridLayer, see the docs for inherited options and methods.

Option	Type	Default	Description
georaster	GeoRaster		Use `georaster` from georaster-library. `georaster` or `georasters` is required.
georasters	GeoRaster[]		Use different `georasters` from georaster-library. `georaster` or `georasters` is required.
resolution	number	32	The resolution parameter is how many samples to take across and down from a dataset for each map tile. Typical tiles are 256 x 256 pixels (higher resolution are 512 x 512) which would be a optimal resolution of 256. It's not recommended to set the resolution higher then 512.
debugLevel	number	0	Available debug levels: 0 - 5
pixelValuesToColorFn	(values: number[]) => string	null	Customize how values for a pixel are translated to a color.
bounds	LatLngBounds	null	https://leafletjs.com/reference.html#latlngbounds
proj4	Function		https://github.com/proj4js/proj4js
resampleMethod	string	nearest	bilinear \| nearest
mask	string \| Feature \| FeatureCollection \| Polygon \| MultiPolygon	null	You can hide all the pixels either inside or outside a given mask geometry. You can provide a JSON object as a mask geometry or a URL to a GeoJSON.
mask_srs	string \| number	"EPSG:4326"	Default mask srs is the EPSG:4326 projection used by GeoJSON
mask_strategy	string	outside	inside \| outside
updateWhenIdle	boolean	true	https://leafletjs.com/reference.html#gridlayer-updatewhenidle
updateWhenZooming	boolean	false	https://leafletjs.com/reference.html#gridlayer-updatewhenzooming
keepBuffer	number	25	https://leafletjs.com/reference.html#gridlayer-keepbuffer

Methods

Method	Returns	Description
getBounds()	LatLngBounds	Returns the bounds of the layer
getMap()	Map	Returns the map which contains the layer
getMapCRS()	CRS	Returns map CRS if available else EPSG3857
getColor(values: number[])	string \| undefined	Returns the colors of the values
updateColors(pixelValuesToColorFn, options = { debugLevel: -1 })	this	Causes the tiles to redraw without clearing them first. It uses the updated `pixelValuesToColorFn` function. You can set a debugLevel specific to this function by passing in an options object with a debugLevel property. For example, you can turn on the console debugs for this method by setting `debugLevel = 1` in the options (even if you created the layer with `debugLevel = 0`).
getTiles()	Tile[]	Returns tiles as array
getActiveTiles()	Tile[]	Returns active / visible tiles as array
isSupportedProjection()	boolean	Returns if the projection is supported
getProjectionString(projection: number)	string	Returns the projection string for example "EPSG:3857"
getProjector()	Projection	Returns the current projection