leaflet-velocity

A plugin for Leaflet (v1.0.3, and v0.7.7) to create a canvas visualisation layer for direction and intensity of arbitrary velocities (e.g. wind, ocean current).

Live Demo: https://danwild.github.io/leaflet-velocity/

• Uses a modified version of WindJS for core functionality.
• Similar to wind-js-leaflet, however much more versatile (provides a generic leaflet layer, and not restricted to wind).
• Data input format is the same as output by wind-js-server, using grib2json.

Example use:

var velocityLayer = L.velocityLayer({
  displayValues: true,
  displayOptions: {
    // label prefix
    velocityType: "Global Wind",
    
    // leaflet control position
    position: "bottomleft",
    
    // no data at cursor
    emptyString: "No velocity data",
    
    // see explanation below
    angleConvention: "bearingCW",
    
    // display cardinal direction alongside degrees
    showCardinal: false,
    
    // one of: ['ms', 'k/h', 'kt']
    speedUnit: "ms",
    
    // direction label prefix
    directionString: "Direction",
    
    // speed label prefix
    speedString: "Speed"
  },
  data: data, // see demo/*.json, or wind-js-server for example data service

  // OPTIONAL
  minVelocity: 0, // used to align color scale
  maxVelocity: 10, // used to align color scale
  velocityScale: 0.005, // modifier for particle animations, arbitrarily defaults to 0.005
  colorScale: [], // define your own array of hex/rgb colors
  onAdd: null, // callback function
  onRemove: null, // callback function
  opacity: 0.97, // layer opacity, default 0.97

  // optional pane to add the layer, will be created if doesn't exist
  // leaflet v1+ only (falls back to overlayPane for < v1)
  paneName: "overlayPane"
});

The angle convention option refers to the convention used to express the wind direction as an angle from north direction in the control. It can be any combination of bearing (angle toward which the flow goes) or meteo (angle from which the flow comes), and CW (angle value increases clock-wise) or CCW (angle value increases counter clock-wise). If not given defaults to bearingCCW.

The speed unit option refers to the unit used to express the wind speed in the control. It can be m/s for meter per second, k/h for kilometer per hour or kt for knots. If not given defaults to m/s.

Public methods

method	params	description
setData	{Object}	update the layer with new data
setOptions	{Object}	update the layer with new options

Build / watch

npm run watch

Reference

leaflet-velocity is possible because of things like:

• L.CanvasOverlay.js
• WindJS
• earth

Example data

Data shown for the Great Barrier Reef has been derived from CSIRO's eReefs products

License

MIT License (MIT)