mirror of
https://github.com/Viglino/ol-ext.git
synced 2026-01-18 17:11:52 +00:00
319 lines
9.6 KiB
HTML
319 lines
9.6 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<!--
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Copyright (c) 2015-2018 Jean-Marc VIGLINO,
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released under CeCILL-B (french BSD like) licence: http://www.cecill.info/
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-->
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<title>ol-ext: Elevation layer</title>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="description" content="[ol-ext] Elevation map" />
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<meta name="keywords" content="ol, openlayers, layer, elevation, altitude, geoportail" />
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<!-- jQuery -->
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<script type="text/javascript" src="https://code.jquery.com/jquery-1.11.0.min.js"></script>
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<!-- Openlayers -->
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<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@latest/ol.css" />
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<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/ol@latest/dist/ol.js"></script>
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<!-- ol-ext -->
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<link rel="stylesheet" href="../../dist/ol-ext.css" />
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<script type="text/javascript" src="../../dist/ol-ext.js"></script>
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<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
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<script src="https://unpkg.com/elm-pep"></script>
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<!-- filesaver-js -->
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<script type="text/javascript" src="https://cdn.rawgit.com/eligrey/FileSaver.js/aa9f4e0e/FileSaver.min.js"></script>
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<link rel="stylesheet" href="../style.css" />
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<style>
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pre {
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padding: .2em 1em;
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margin: .2em 1em;
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background: #ddd;
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width: auto;
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display: inline-block;
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}
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</style>
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</head>
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<body >
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<a href="https://github.com/Viglino/ol-ext" class="icss-github-corner"><i></i></a>
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<a href="../../index.html">
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<h1>ol-ext: x-bil elevation layer</h1>
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</a>
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<div class="info">
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This example use a TileWMS layer with an x-bil (Band Interleaved by Line) image format and a
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<a href="https://openlayers.org/en/latest/apidoc/module-ol_Tile.html#~LoadFunction">tileLoadFunction</a>
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to encode altitude as RGB pixels.
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<br/>
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The following equation will decode pixel values to height values:
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<br/>
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<pre>height = -12000 + ((R * 256 * 256 + G * 256 + B) * 0.01)</pre>
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<br/>
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It ensure a 2 digit precision and a maximum deep watter trench up to -12000 m.
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<br/>
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Use the <i>ol.ext.getElevationFromPixel</i> function to get elevation from RGB pixel value.
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</div>
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<!-- DIV pour la carte -->
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<div id="map" style="width: 100%; height: 600px;"></div>
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<label>
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<input type="checkbox" onchange="hide.setDisplay(this.checked)"/>
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display elevation map
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</label>
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<script>
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var plan = new ol.layer.Geoportail({
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layer: 'GEOGRAPHICALGRIDSYSTEMS.PLANIGNV2',
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className: 'plan',
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});
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// The map
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var map = new ol.Map ({
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target: 'map',
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view: new ol.View ({
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zoom: 0,
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center: [951487, 3467896]
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}),
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layers: [ plan ]
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});
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map.addControl(new ol.control.LayerSwitcher());
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map.addControl(new ol.control.Permalink({ visible: false }));
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map.addControl(new ol.control.SearchNominatim({ zoomOnSelect: 16 }));
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// A set of elevation layers
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var layers = [
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{
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title: 'MNT SRTM3',
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url: 'https://data.geopf.fr/wms-r/wms',
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layer: 'ELEVATION.ELEVATIONGRIDCOVERAGE.SRTM3',
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//extent: [ -20037554.725947514, -8625918.87376409, 20037554.725947514, 8625918.87376409 ]
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},{
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title: 'MNS',
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url: 'https://data.geopf.fr/wms-r/wms',
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layer: 'ELEVATION.ELEVATIONGRIDCOVERAGE.HIGHRES.MNS',
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extent: [ -578959.605490584, 5203133.393641367, 921974.2487313666, 6643289.75487211 ]
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}, {
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title: 'MNT-RGE-Alti',
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url: 'https://data.geopf.fr/wms-r/wms',
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layer: 'ELEVATION.ELEVATIONGRIDCOVERAGE.HIGHRES',
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extent: [ -7007874.496280316, -1460624.494037931, 5043253.3127169, 6639937.650114076 ]
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}, {
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title: 'MNT BDAlti V1',
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url: 'https://data.geopf.fr/wms-r/wms',
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layer: 'ELEVATION.ELEVATIONGRIDCOVERAGE',
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extent: [ -7007874.496280316, -1460624.494037931, 5043253.3127169, 6639937.650114076 ]
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}
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];
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// Add tile layer
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var layer = layers[2]
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var elev = new ol.layer.Tile ({
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title: layer.title,
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displayInLayerSwitcher: false,
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extent: layer.extent,
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minResolution: 0,
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maxResolution: 197231.79878968254,
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source: new ol.source.TileWMS({
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url: layer.url,
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projection: 'EPSG:3857',
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attributions: [ 'Geoservices-IGN' ],
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crossOrigin: 'anonymous',
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params: {
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LAYERS: layer.layer,
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FORMAT: 'image/x-bil;bits=32',
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VERSION: '1.3.0'
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}
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})
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});
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map.addLayer(elev);
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// Tile load function to convert elevation
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var alti = ol.ext.imageLoader.elevationMap();
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elev.getSource().setTileLoadFunction(alti);
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// Hide the layer (but keep it on the map)
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var hide = new ol.filter.CSS({ display: false });
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elev.addFilter(hide);
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// Prevent layer smoothing
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elev.once('prerender', function(evt) {
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evt.context.imageSmoothingEnabled = false;
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evt.context.webkitImageSmoothingEnabled = false;
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evt.context.mozImageSmoothingEnabled = false;
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evt.context.msImageSmoothingEnabled = false;
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});
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// Add a popup to display elevation
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var popup = new ol.Overlay.Tooltip();
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map.addOverlay(popup)
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map.on('pointermove', function(e) {
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var pix = elev.getData(e.pixel);
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var h = ol.ext.getElevationFromPixel(pix);
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popup.setInfo(h > -5000 ? h.toFixed(2)+' m' : '');
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});
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// SHADE
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/**
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* Generates a shaded relief image given elevation data. Uses a 3x3
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* neighborhood for determining slope and aspect.
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* @param {Array<ImageData>} inputs Array of input images.
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* @param {Object} data Data added in the "beforeoperations" event.
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* @return {ImageData} Output image.
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*/
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function shade(inputs, data) {
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const elevationImage = inputs[0];
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const width = elevationImage.width;
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const height = elevationImage.height;
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const elevationData = elevationImage.data;
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const shadeData = new Uint8ClampedArray(elevationData.length);
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const dp = data.resolution * 2;
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const maxX = width - 1;
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const maxY = height - 1;
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const pixel = [0, 0, 0, 0];
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const twoPi = 2 * Math.PI;
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const halfPi = Math.PI / 2;
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const sunEl = (Math.PI * data.sunEl) / 180;
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const sunAz = (Math.PI * data.sunAz) / 180;
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const cosSunEl = Math.cos(sunEl);
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const sinSunEl = Math.sin(sunEl);
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let pixelX,
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pixelY,
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x0,
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x1,
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y0,
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y1,
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offset,
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z0,
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z1,
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dzdx,
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dzdy,
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slope,
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aspect,
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cosIncidence,
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scaled;
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function calculateElevation(pixel) {
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// The method used to extract elevations from the DEM.
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// In this case the format used is
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// red + green * 2 + blue * 3
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//
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// Other frequently used methods include the Mapbox format
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// (red * 256 * 256 + green * 256 + blue) * 0.1 - 10000
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// and the Terrarium format
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// (red * 256 + green + blue / 256) - 32768
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//
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// return pixel[0] + pixel[1] * 2 + pixel[2] * 3;
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return -12000 + ((pixel[0] << 16) + (pixel[1] << 8) + pixel[2]) * 0.01;
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// return -12000 + ((pixel[0] * 256 * 256 + pixel[1] * 256 + pixel[2]) * 0.01)
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}
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for (pixelY = 0; pixelY <= maxY; ++pixelY) {
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y0 = pixelY === 0 ? 0 : pixelY - 1;
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y1 = pixelY === maxY ? maxY : pixelY + 1;
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for (pixelX = 0; pixelX <= maxX; ++pixelX) {
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x0 = pixelX === 0 ? 0 : pixelX - 1;
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x1 = pixelX === maxX ? maxX : pixelX + 1;
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// determine elevation for (x0, pixelY)
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offset = (pixelY * width + x0) * 4;
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pixel[0] = elevationData[offset];
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pixel[1] = elevationData[offset + 1];
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pixel[2] = elevationData[offset + 2];
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pixel[3] = elevationData[offset + 3];
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z0 = data.vert * calculateElevation(pixel);
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// determine elevation for (x1, pixelY)
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offset = (pixelY * width + x1) * 4;
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pixel[0] = elevationData[offset];
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pixel[1] = elevationData[offset + 1];
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pixel[2] = elevationData[offset + 2];
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pixel[3] = elevationData[offset + 3];
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z1 = data.vert * calculateElevation(pixel);
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dzdx = (z1 - z0) / dp;
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// determine elevation for (pixelX, y0)
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offset = (y0 * width + pixelX) * 4;
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pixel[0] = elevationData[offset];
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pixel[1] = elevationData[offset + 1];
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pixel[2] = elevationData[offset + 2];
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pixel[3] = elevationData[offset + 3];
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z0 = data.vert * calculateElevation(pixel);
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// determine elevation for (pixelX, y1)
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offset = (y1 * width + pixelX) * 4;
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pixel[0] = elevationData[offset];
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pixel[1] = elevationData[offset + 1];
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pixel[2] = elevationData[offset + 2];
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pixel[3] = elevationData[offset + 3];
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z1 = data.vert * calculateElevation(pixel);
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dzdy = (z1 - z0) / dp;
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slope = Math.atan(Math.sqrt(dzdx * dzdx + dzdy * dzdy));
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aspect = Math.atan2(dzdy, -dzdx);
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if (aspect < 0) {
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aspect = halfPi - aspect;
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} else if (aspect > halfPi) {
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aspect = twoPi - aspect + halfPi;
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} else {
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aspect = halfPi - aspect;
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}
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cosIncidence =
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sinSunEl * Math.cos(slope) +
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cosSunEl * Math.sin(slope) * Math.cos(sunAz - aspect);
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offset = (pixelY * width + pixelX) * 4;
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scaled = Math.round(255 * cosIncidence);
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shadeData[offset] = 0;
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shadeData[offset + 1] = 0;
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shadeData[offset + 2] = 0;
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shadeData[offset + 3] = scaled;
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}
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}
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return {data: shadeData, width: width, height: height};
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}
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const raster = new ol.source.Raster({
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sources: [elev.getSource()],
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operationType: 'image',
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operation: shade,
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});
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var shade = new ol.layer.Image({
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title: 'Shaded relief',
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className: 'shade',
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opacity: .5,
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source: raster,
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})
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var blurFilter = new ol.filter.CSS({ filter: 'blur(2px)' });
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shade.addFilter(blurFilter)
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map.addLayer(shade)
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map.getView().on('change:resolution', function() {
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blurFilter.setFilter('blur('+Math.round(map.getView().getZoom()/4)+'px)')
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})
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var controls = {
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vert: 5,
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sunEl: 0,
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sunAz: 180
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}
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raster.on('beforeoperations', function (event) {
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// the event.data object will be passed to operations
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const data = event.data;
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data.resolution = event.resolution;
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for (const id in controls) {
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data[id] = Number(controls[id]);
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}
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});
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</script>
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</body>
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</html> |