How to use CesiumJS to visualize data from a Session

Heightmap

Most of the time you want to use the heightmap of your project's session, instead of the default digital elevation height that Cesium provides. Use this code for a custom heightmap provider.

// variables
const dim = 128;
const minLevel = 6;
const maxLevel = 19;
const tilepx = 512;

// Construct the default list of terrain sources.
var terrainModels = [];
terrainModels.push(new Cesium.ProviderViewModel({
	name: "Project Terrain",
	category: "Terrain",
	iconUrl: Cesium.buildModuleUrl('Widgets/Images/TerrainProviders/Ellipsoid.png'),
	creationFunction: function () {
		return new Cesium.CustomHeightmapTerrainProvider({
			width: dim,
			height: dim,
			maximumLevel: maxLevel,
			callback: function (x, y, level) {
				if (level <= 10) { // ignore zoom levels 10 and lower
					return new Float32Array(dim * dim); // all zeros
				}
				const test = Cesium.Resource.fetchArrayBuffer('terrain/' + level + '/' + x + '/' + y + '.bin?worlddatum=true&token=$TOKEN&width=' + dim + '&height=' + dim);
				return test.then(function (buffer) {
					const array = new Float32Array(dim * dim); // all zeros
					const view = new DataView(buffer);
					for (let i = 0; i < dim * dim; i++) {
						array[i] = view.getFloat32(i * 4);
					}
					return array;
				});
			},
		});
	}
}));

Base Map WMS

You can use the following code to add and access your project's WMS. Additionally, you can provide the optional layer parameter: SATELLITE, TOPOGRAPHIC or GRAY.

var imageryViewModels = [];
const baseMaps = ["SATELLITE", "TOPOGRAPHIC", "GRAY"];
	for (let i = 0; i < baseMaps.length; i++) {
	imageryViewModels.push(new Cesium.ProviderViewModel({
		name: baseMaps[i],
		category: "Base Map",
		iconUrl: Cesium.buildModuleUrl('Widgets/Images/TerrainProviders/Ellipsoid.png'),
		creationFunction: function () {
			return new Cesium.WebMapServiceImageryProvider({
				url: 'wms',
				layers: baseMaps[i],
				maximumLevel: maxLevel,
				tileHeight: tilepx,
				tileWidth: tilepx,
				getFeatureInfoFormats: [new Cesium.GetFeatureInfoFormat("json", "application/json")],
				proxy: new Cesium.DefaultProxy('/proxy/'),
				parameters: {
					crs: "4326",
					forcexy: "true",
					bgcolor: "$BGCOLOR",
					walled: "false",
					token: "$TOKEN"
				},
				getFeatureInfoParameters: {
					crs: "4326",
					forcexy: "true",
					token: "$TOKEN",
				},
				clock: WMS_CLOCK,
				times: WMS_TIMES
			});
		}
	}));
}

Viewer initialization

The Cesium viewer is initialized as followed:

// Construct the viewer, with a high-res terrain source pre-selected.
var viewer = new Cesium.Viewer('cesiumContainer', {
	terrainProviderViewModels: terrainModels,
	selectedTerrainProviderViewModel: terrainModels[0],
	imageryProviderViewModels: imageryViewModels,
	selectedImageryProviderViewModel: imageryViewModels[$BASEMAP_INDEX],
	animation: false,
	timeline: false,
	homeButton: false,
	navigationHelpButton: false,
	navigationInstructionsInitiallyVisible: false,
	fullscreenButton: false,
	shadows: $SHADOW,
});

3D Tileset

A 3D tileset can be added by activating an asynchronous function and awaiting the tileset call:

const start = async function () {	
	tileset = await Cesium.Cesium3DTileset.fromUrl('3dtiles/tileset.json?token=$TOKEN&style=$STYLE&spacing=$SPACING&texture=$TEXTURE');
	viewer.scene.primitives.add(tileset);
}

Fly camera to Tileset

Once loaded, the camera can fly to the tileset by adding this after the tileset has been added to the scene (but before the end bracket of the start function)

boundingSphere = tileset.root.boundingVolume._boundingSphere
viewer.camera.viewBoundingSphere(tileset.root.boundingVolume._boundingSphere);
viewer.camera.flyToBoundingSphere(tileset.root.boundingVolume._boundingSphere);

Updating the Tileset

A tileset can be updated with the following code

var tileseturl = new Cesium.Resource({
	url: "3dtiles/tileset.json",
	queryParameters: {
		token: "$TOKEN"
	}
});
tileseturl.fetchJson().then(data => {
	if (tilesetversion == null) {
		tilesetversion = data.asset.tilesetVersion;
	} else if (data.asset.tilesetVersion > tilesetversion) {

		tilesetversion = data.asset.tilesetVersion;
		var tilerequest = Cesium.Cesium3DTileset.fromUrl('3dtiles/tileset.json?token=$TOKEN&style=$STYLE&spacing=$SPACING&texture=$TEXTURE');
		tilerequest.then((newtileset) => {

			viewer.scene.primitives.add(newtileset);
			tileset.show = false;
			viewer.scene.primitives.remove(tileset);
			tileset = newtileset;
		});
	}
});

Overlays

Overlays are also provided by a project's WMS. The code below allows you to add overlays to the Cesium viewer. Overlay layer is a variable that stores the current overlay layer, such that it can also be destroyed when it should no longer be visible. Parameters "maxLevel" and "tilepx" are defined above in #HeightMap.

const provider = new Cesium.WebMapServiceImageryProvider({
	url: 'wms',
	layers: overlayID,
	maximumLevel: maxLevel,
	tileHeight: tilepx,
	tileWidth: tilepx,
	proxy: new Cesium.DefaultProxy('/proxy/'),
	parameters: {
		crs: "4326",
		forcexy: "true",
		token: "$TOKEN",
		timeframe: timeframe,
		styles: difference ? "DIFFERENCE" : "",
		version: version
	},
	getFeatureInfoParameters: {
		crs: "4326",
		forcexy: "true",
		token: "$TOKEN",
		timeframe: timeframe,
		styles: difference ? "DIFFERENCE" : "",
		version: version
	}
});

viewer.imageryLayers.remove(overlayLayer);
var newOverlayLayer = new Cesium.ImageryLayer(provider, { minimumTerrainLevel: minLevel });
viewer.imageryLayers.add(newOverlayLayer);
overlayControl.setActiveOverlayLayer(newOverlayLayer);
if (overlayLayer != null) {
	overlayLayer.destroy();
}

Variables

• $TOKEN = API token.
• $BGCOLOR = Hexa-color.
• $BASEMAP_INDEX = nominal; SATELLITE=0, TOPOGRAPHIC=1 and GRAY=2.
• $SHADOW = boolean.
• $SPACING = distance number.
• $TEXTURE = String value. Allowed: "SMALL", "MEDIUM" or "LARGE".
• $STYLE = String value. Allowed: "WHITE", "COLORED".

See also

• Cesium
• 3D Tiles
• 3D Web Viewer