georaster-layer-for-leaflet

🇺🇦 “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"></script>

Usage

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

Demos

Why

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 => {
    parseGeoraster(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

Advanced Capabilities

Please read about our advanced capabilities including custom context drawing functions, displaying directional arrows, and masking in ADVANCED.md.

More Questions

Check out our Frequently Asked Questions

Videos

Support

Contact the package author, Daniel J. Dufour, at daniel.j.dufour@gmail.com

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