WMS Time

wms 12 time 1 dimensions 1 transition 3 nexrad 1

Example of smooth tile transitions when changing the time dimension of a tiled WMS layer.

Demonstrates smooth reloading of layers when changing the time dimension continuously. Data shown: IEM generated CONUS composite of NWS NEXRAD WSR-88D level III base reflectivity.

main.js

import Map from 'ol/Map.js';
import View from 'ol/View.js';
import {getCenter} from 'ol/extent.js';
import TileLayer from 'ol/layer/Tile.js';
import {transformExtent} from 'ol/proj.js';
import StadiaMaps from 'ol/source/StadiaMaps.js';
import TileWMS from 'ol/source/TileWMS.js';

const interval = 3 * 60 * 60 * 1000;
const step = 15 * 60 * 1000;
const frameRate = 0.5; // frames per second
const extent = transformExtent([-126, 24, -66, 50], 'EPSG:4326', 'EPSG:3857');

let wmsTime = new Date();
let animationId = null;

const stadiaLayer = new TileLayer({
  source: new StadiaMaps({
    layer: 'stamen_terrain',
  }),
});
const tileWmsLayer = new TileLayer({
  extent: extent,
  source: new TileWMS({
    attributions: ['Iowa State University'],
    url: 'https://mesonet.agron.iastate.edu/cgi-bin/wms/nexrad/n0r-t.cgi',
    params: {'LAYERS': 'nexrad-n0r-wmst'},
  }),
});

const map = new Map({
  layers: [stadiaLayer, tileWmsLayer],
  target: 'map',
  view: new View({
    center: getCenter(extent),
    zoom: 4,
  }),
});

const el = document.getElementById('info');
function updateInfo(time) {
  el.innerHTML = time.toISOString();
}

function threeHoursAgo() {
  return new Date(Math.floor((Date.now() - interval) / step) * step);
}

function setTime() {
  wmsTime.setMinutes(wmsTime.getMinutes() + 15);
  if (wmsTime.getTime() > Date.now()) {
    wmsTime = threeHoursAgo();
  }
  tileWmsLayer.getSource().updateParams({'TIME': wmsTime.toISOString()});
  updateInfo(wmsTime);
}
setTime();

const stop = function () {
  if (animationId !== null) {
    window.clearInterval(animationId);
    animationId = null;
  }
};

const play = function () {
  stop();
  animationId = window.setInterval(setTime, 1000 / frameRate);
};

const startButton = document.getElementById('play');
startButton.addEventListener('click', play, false);

const stopButton = document.getElementById('pause');
stopButton.addEventListener('click', stop, false);

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WMS Time</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div role="group" aria-label="Animation controls">
      <button id="play" type="button">Play</button>
      <button id="pause" type="button">Pause</button>
      <span id="info"></span>
    </div>

    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "wms-time",
  "dependencies": {
    "ol": "10.5.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}