WCS Layer with Pixel Filter | ArcGIS API for JavaScript 3.26

The WCSLayer retrieves coverage (raster) data and renderers it on the client. It supports version 1.0.0, 1.1.x, and 2.0.1. For version 2.0.1, it supports servers that support GEOTIFF coverage and implements the following extensions: Scaling, Interpolation, Range Subsetting, CRS, and KVP/Get.

Code


<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
  <title>WCS Layer with Pixel Filter</title>
  <link rel="stylesheet" href="https://js.arcgis.com/3.26/dijit/themes/claro/claro.css">
  <link rel="stylesheet" href="https://js.arcgis.com/3.26/esri/css/esri.css">
  <style>
    html, body, #map {
      width: 100%;
      height: 100%;
      margin: 0;
      padding: 0;
    }

    #topic {
      font-weight: 600;
      font-size: 130%;
    }

    #status {
      background-color: #000000;
      color: #FFFFFF;
      border: solid 1px #FFFFFF;
      -moz-border-radius: 5px;
      -webkit-border-radius: 5px;
      border-radius: 5px;
      padding: 3px;
      position: absolute;
      right: 10px;
      bottom: 10px;
      z-index: 99;
    }

    .shadow {
      -moz-border-radius: 6px;
      -webkit-border-radius: 6px;
      border-radius: 6px;
      background-color: #FFFFFF;
      padding: 8px;
    }

    #footer {
      height: 90px;
      width: 300px;
      margin: 0 auto;
      padding: 15px;
      position: absolute;
      bottom: 20px;
      left: 20px;
      z-index: 30;
    }
  </style>
   <script src="https://js.arcgis.com/3.26"></script>
  <script>
    require([
      "dijit/registry",
      "dojo/dom",
      "dojo/mouse",
      "dojo/on",
      "dojo/parser",
      "dijit/form/ComboBox",
      "esri/config",
      "esri/domUtils",
      "esri/geometry/Circle",
      "esri/geometry/webMercatorUtils",
      "esri/graphic",
      "esri/layers/WCSLayer",
      "esri/map",
      "esri/symbols/SimpleFillSymbol",
      "dojo/domReady!"
    ], function(registry, dom, mouse, on, parser, ComboBox, esriConfig, domUtils, Circle, WebMercatorUtils, Graphic, WCSLayer, Map, SimpleFillSymbol) {
      parser.parse();
      var wcsUrl = "https://sampleserver6.arcgisonline.com/arcgis/services/ScientificData/MODIS_Landcover/ImageServer/WCSServer";

      var symbol = new SimpleFillSymbol().setColor(null).outline.setColor("blue");

      var map = new Map("map", {
        basemap: "dark-gray",
        center: [-60, 36],
        zoom: 4
      });

      //enable request of sea surface temperature image service via CORS
      var corsEnabledServers = esriConfig.defaults.io.corsEnabledServers;
      corsEnabledServers.push("sampleserver6.arcgisonline.com");
      //WCS GetCoverage uses the onlineResource url (in capabilities response) instead of wcsUrl.
      // This server explicitly specifies port 80 (for http requests)
      // and 443 (for https requests) in the online resource, so we need to push it in too.
      corsEnabledServers.push("sampleserver6.arcgisonline.com:443");

      /******************************************************************************************************
       * This WCS service serves discrete land cover data, which can be better rendered by colorizing them
       * Unlike image service, WCS model does not have raster attribute table resource
       *******************************************************************************************************/
      var colorMap = [
        [0, 0, 255], [0, 100, 70], [0, 92, 22], [0, 143, 26], [0, 160, 70], [55, 143, 0],
        [117, 128, 0], [117, 128, 0], [94, 83, 0], [94, 83, 0], [74, 222, 0], [104, 104, 104],
        [255, 255, 155], [255, 85, 0], [135, 158, 0], [255, 255, 255], [230, 152, 0]
      ];
      var landTypes = [
        "Water", "Evergreen Needleleaf forest", "Evergreen Broadleaf forest", "Deciduous Needleleaf forest",
        "Deciduous Broadleaf forest", "Mixed forest", "Closed shrublands", "Open shrublands", "Woody savannas",
        "Savannas", "Grasslands", "Permanent wetlands", "Croplands", "Urban and built-up",
        "Cropland/Natural vegetation mosaic", "Snow and ice", "Barren or sparsely vegetated"
      ];

      //Define the raster layer and add to map
      var wcsLayer = new WCSLayer(wcsUrl, {
        version: "1.0.0",
        pixelFilter: colorizer
      });

      map.addLayer(wcsLayer);
      map.on("mouse-move", onMapMove);
      map.on("mouse-down", function (){
        map.infoWindow.hide();
      });

      wcsLayer.on("update-start", function (){
        domUtils.show(dom.byId("status"));
      });
      wcsLayer.on("update-end", function (){
        domUtils.hide(dom.byId("status"));
      });

      on(dom.byId("footer"), mouse.enter, function (evt){
        if (map) {
          map.infoWindow.hide();
        }
      });

      //show pixel code, type
      function onMapMove(evt){
        if (!map || !wcsLayer || !wcsLayer.originalPixelData) {
          return;
        }

        map.graphics.clear();
        map.infoWindow.hide();
        map.infoWindow.resize(200, 150);

        var template = "<b>Land Cover</b><hr><b> Code: ${Code}</b></br><b>Type: ${ClassName}</b></br><b>Long: ${X}W</b></br><b>Lat: ${Y}N</b>";
        var resolution = wcsLayer.getCurrentResolution();
        var pixelBlock = wcsLayer.originalPixelData.pixelBlock;
        var width = pixelBlock.width;
        var pixels = pixelBlock.pixels[0];
        var offsetX = Math.round((map.extent.xmin - wcsLayer.originalPixelData.extent.xmin) / resolution.x);
        var offsetY = Math.round((map.extent.ymax - wcsLayer.originalPixelData.extent.ymax) / resolution.y);
        var reqX = evt.layerX - offsetX;
        var reqY = evt.layerY - offsetY;
        var pixelIndex = Math.floor(reqY * width + reqX);
        var latLongPoint = WebMercatorUtils.webMercatorToGeographic(evt.mapPoint);
        if (pixelBlock.mask === null || pixelBlock.mask[pixelIndex]) {
          var o = {
            Code: pixels[pixelIndex],
            ClassName: landTypes[pixels[pixelIndex]],
            X: latLongPoint.x,
            Y: latLongPoint.y
          };
          if (highlightedValue === -1 || o.Code === highlightedValue) {
            map.infoWindow.setContent(template.replace("${Code}", o.Code).replace("${ClassName}", o.ClassName)
              .replace("${X}", o.X.toFixed(6)).replace("${Y}", o.Y.toFixed(6)));
            map.infoWindow.show(evt.screenPoint,
              map.getInfoWindowAnchor(evt.screenPoint));
          }
        }

        var circle = new Circle({
          center: evt.mapPoint,
          radius: 1
        });

        var graphic = new Graphic(circle, symbol);
        map.graphics.add(graphic);
      }

      var highlightedValue = -1;
      on(registry.byId("landTypeCombo"),'change', function(val) {
        highlightedValue = landTypes.findIndex(function (x){
          return x === val;
        });
        wcsLayer.redraw();
      });

      // The pixel filter
      function colorizer(pixelData){
        if (!pixelData || !pixelData.pixelBlock) {
          return;
        }
        var pixelBlock = pixelData.pixelBlock;
        var pixels = pixelBlock.pixels;
        var mask = pixelBlock.mask;
        var numPixels = pixelBlock.width * pixelBlock.height;
        if (!pixels) {
          return;
        }
        var p1 = pixels[0];
        var pr = new Uint8Array(p1.length); //set up array for red values
        var pg = new Uint8Array(p1.length); //set up array for green values
        var pb = new Uint8Array(p1.length); //set up array for blue values
        var color, i;
        if (!mask && highlightedValue === -1) {
          for (i = 0; i < numPixels; i++) {
            color = colorMap[p1[i]];
            pr[i] = color[0];  //red
            pg[i] = color[1];  //green
            pb[i] = color[2];  //blue
          }
        }
        else {
          if (mask) {
            for (i = 0; i < numPixels; i++) {
              if (mask[i]) {
                if (p1[i] === highlightedValue) {
                  color = colorMap[p1[i]];
                  pr[i] = color[0];  //red
                  pg[i] = color[1];  //green
                  pb[i] = color[2];  //blue
                }
                else {
                  mask[i] = 0;
                }
              }
            }
          }
          else {
            mask = new Uint8Array(p1.length);
            for (i = 0; i < numPixels; i++) {
              //apply color based on temperature value of each pixel
              if (p1[i] === highlightedValue) {
                color = colorMap[p1[i]];
                pr[i] = color[0];  //red
                pg[i] = color[1];  //green
                pb[i] = color[2];  //blue
                mask[i] = 1;
              }
              else {
                mask[i] = 0;
              }
            }
            pixelData.pixelBlock.mask = mask;//attach the mask
          }
        }
        pixelData.pixelBlock.pixels = [pr, pg, pb];  //assign rgb values to each pixel
        pixelData.pixelBlock.statistics = null;
        pixelData.pixelBlock.pixelType = "U8";
      }
    });
  </script>
</head>
<body class="claro">
  <div id="map">
    <div id="status">
      Loading...
    </div>
    <div id="footer" class="shadow">
      <span id='topic'>Global Land Cover Data</span><br><br>
      <div>
        Show Land Type:
        <select data-dojo-type="dijit/form/ComboBox" id="landTypeCombo">
          <option selected>All</option>
          <option>Water</option>
          <option>Evergreen Needleleaf forest</option>
          <option>Evergreen Broadleaf forest</option>
          <option>Deciduous Needleleaf forest</option>
          <option>Deciduous Broadleaf forest</option>
          <option>Mixed forest</option>
          <option>Closed shrublands</option>
          <option>Open shrublands</option>
          <option>Woody savannas</option>
          <option>Savannas</option>
          <option>Grasslands</option>
          <option>Permanent wetlands</option>
          <option>Croplands</option>
          <option>Urban and built-up</option>
          <option>Cropland/Natural vegetation mosaic</option>
          <option>Snow and ice</option>
        </select>
      </div>
    </div>
  </div>
</body>
</html>

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