cesiumjs-entities

CesiumJS Entities & DataSources

Version baseline: CesiumJS 1.139 -- ES module imports: import { ... } from "cesium"; Ownership rule: *Graphics classes belong here; *Geometry classes belong in cesiumjs-primitives. Properties (SampledProperty, CallbackProperty, MaterialProperty subtypes) belong in cesiumjs-time-properties.

Architecture

The Entity API is the high-level, data-driven layer of CesiumJS. Entities combine position, orientation, and one or more Graphics types into a single object managed by an EntityCollection. DataSources load external formats (GeoJSON, KML, CZML, GPX) and populate an EntityCollection automatically. Visualizers and GeometryUpdaters translate Entity descriptions into Primitives each frame.

DataSource --> EntityCollection --> Entity
                                     |-- position / orientation
                                     |-- billboard / point / label / model / polygon / polyline / ...
                                     |-- properties (PropertyBag)

• viewer.entities is a shortcut to the default DataSource's EntityCollection
• viewer.dataSources holds all loaded DataSources; each owns an EntityCollection

Entity Basics

Point

import { Viewer, Cartesian3, Color, HeightReference } from "cesium";

const viewer = new Viewer("cesiumContainer");
const entity = viewer.entities.add({
  id: "my-point",                 // optional; auto-generated GUID if omitted
  name: "Sample Point",
  position: Cartesian3.fromDegrees(-75.59777, 40.03883),
  point: {
    pixelSize: 10,
    color: Color.YELLOW,
    outlineColor: Color.BLACK,
    outlineWidth: 2,
    heightReference: HeightReference.CLAMP_TO_GROUND,
  },
});
viewer.zoomTo(entity);

Billboard with Label

import { Viewer, Cartesian3, Cartesian2, Color, VerticalOrigin, HeightReference, LabelStyle } from "cesium";

const viewer = new Viewer("cesiumContainer");
viewer.entities.add({
  position: Cartesian3.fromDegrees(-122.4175, 37.7749),
  billboard: {
    image: "/assets/marker.png",
    scale: 0.5,
    verticalOrigin: VerticalOrigin.BOTTOM,
    heightReference: HeightReference.CLAMP_TO_GROUND,
  },
  label: {
    text: "San Francisco",
    font: "14px sans-serif",
    fillColor: Color.WHITE,
    outlineColor: Color.BLACK,
    outlineWidth: 2,
    style: LabelStyle.FILL_AND_OUTLINE,
    pixelOffset: new Cartesian2(0, -36),
    heightReference: HeightReference.CLAMP_TO_GROUND,
  },
});

Polygon (flat, extruded, with holes)

import { Viewer, Cartesian3, Color, PolygonHierarchy } from "cesium";

const viewer = new Viewer("cesiumContainer");
// Flat polygon
viewer.entities.add({
  polygon: {
    hierarchy: Cartesian3.fromDegreesArray([-115, 37, -115, 32, -107, 33, -102, 31, -102, 35]),
    material: Color.RED.withAlpha(0.5),
    outline: true,
    outlineColor: Color.BLACK,
  },
});
// Extruded polygon with hole
viewer.entities.add({
  polygon: {
    hierarchy: new PolygonHierarchy(
      Cartesian3.fromDegreesArray([-99, 30, -85, 30, -85, 40, -99, 40]),
      [new PolygonHierarchy(Cartesian3.fromDegreesArray([-97, 32, -87, 32, -87, 38, -97, 38]))]
    ),
    extrudedHeight: 300000,
    material: Color.BLUE.withAlpha(0.6),
    closeTop: true,
    closeBottom: true,
  },
});

Polyline

import { Viewer, Cartesian3, Color, ArcType } from "cesium";

const viewer = new Viewer("cesiumContainer");
viewer.entities.add({
  polyline: {
    positions: Cartesian3.fromDegreesArray([-75, 35, -125, 35]),
    width: 5,
    material: Color.RED,
    arcType: ArcType.GEODESIC,
    clampToGround: true,
  },
});

3D Model

import { Viewer, Cartesian3, HeadingPitchRoll, Transforms, Math as CesiumMath, Color } from "cesium";

const viewer = new Viewer("cesiumContainer");
const position = Cartesian3.fromDegrees(-123.075, 44.045, 5000);
const hpr = new HeadingPitchRoll(CesiumMath.toRadians(135), 0, 0);

viewer.entities.add({
  position,
  orientation: Transforms.headingPitchRollQuaternion(position, hpr),
  model: {
    uri: "/assets/CesiumAir/Cesium_Air.glb",
    minimumPixelSize: 64,
    maximumScale: 20000,
    silhouetteColor: Color.RED,
    silhouetteSize: 2,
  },
});

Box, Cylinder, Ellipsoid, Ellipse

import { Viewer, Cartesian3, Color } from "cesium";
const viewer = new Viewer("cesiumContainer");

viewer.entities.add({  // Box
  position: Cartesian3.fromDegrees(-107, 40, 300000),
  box: { dimensions: new Cartesian3(400000, 300000, 500000), material: Color.BLUE.withAlpha(0.5) },
});
viewer.entities.add({  // Cylinder (topRadius: 0 for a cone)
  position: Cartesian3.fromDegrees(-100, 40, 200000),
  cylinder: { length: 400000, topRadius: 200000, bottomRadius: 200000, material: Color.GREEN.withAlpha(0.5) },
});
viewer.entities.add({  // Ellipsoid (sphere when all radii equal)
  position: Cartesian3.fromDegrees(-93, 40, 300000),
  ellipsoid: { radii: new Cartesian3(200000, 200000, 300000), material: Color.RED.withAlpha(0.5) },
});
viewer.entities.add({  // Ellipse (circle when axes equal)
  position: Cartesian3.fromDegrees(-86, 40),
  ellipse: { semiMajorAxis: 300000, semiMinorAxis: 300000, material: Color.PURPLE.withAlpha(0.5) },
});

Corridor, Rectangle, Wall

import { Viewer, Cartesian3, Color, Rectangle, CornerType } from "cesium";
const viewer = new Viewer("cesiumContainer");

viewer.entities.add({  // Corridor: path with width
  corridor: { positions: Cartesian3.fromDegreesArray([-80, 40, -90, 40, -90, 35]), width: 200000, material: Color.ORANGE.withAlpha(0.6), cornerType: CornerType.ROUNDED },
});
viewer.entities.add({  // Rectangle by geographic bounds
  rectangle: { coordinates: Rectangle.fromDegrees(-110, 20, -80, 25), material: Color.GREEN.withAlpha(0.5), extrudedHeight: 50000 },
});
viewer.entities.add({  // Wall: vertical curtain
  wall: { positions: Cartesian3.fromDegreesArrayHeights([-115, 44, 200000, -90, 44, 200000]), minimumHeights: [100000, 100000], material: Color.CYAN.withAlpha(0.7) },
});

EntityCollection Operations

viewer.entities.getById("my-point");               // retrieve by ID
viewer.entities.getOrCreateEntity("some-id");       // get or create
viewer.entities.values;                             // Entity[] (read-only)
viewer.entities.remove(entity);                     // remove by reference
viewer.entities.removeById("my-point");             // remove by ID
viewer.entities.removeAll();                        // clear all

// Batch updates -- suspend events for bulk add/remove
viewer.entities.suspendEvents();
for (let i = 0; i < 1000; i++) viewer.entities.add({ /* ... */ });
viewer.entities.resumeEvents();  // fires one collectionChanged event

viewer.entities.collectionChanged.addEventListener((collection, added, removed, changed) => {
  console.log(`Added: ${added.length}, Removed: ${removed.length}`);
});

DataSources

GeoJSON / TopoJSON

import { Viewer, GeoJsonDataSource, Color } from "cesium";
const viewer = new Viewer("cesiumContainer");

// Load from URL with styling options
const ds = await GeoJsonDataSource.load("/data/counties.geojson", {
  stroke: Color.HOTPINK, fill: Color.PINK.withAlpha(0.5), strokeWidth: 3, clampToGround: true,
});
viewer.dataSources.add(ds);
viewer.zoomTo(ds);

// Post-load styling: iterate and customize
for (const entity of ds.entities.values) {
  if (entity.polygon) entity.polygon.material = Color.fromRandom({ alpha: 0.8 });
}

GeoJsonDataSource.load() also accepts an inline GeoJSON object instead of a URL.

KML / KMZ

import { KmlDataSource } from "cesium";
const ds = await KmlDataSource.load("/data/sample.kml", {
  camera: viewer.scene.camera, canvas: viewer.scene.canvas, clampToGround: true,
});
viewer.dataSources.add(ds);
viewer.flyTo(ds);

CZML

import { CzmlDataSource } from "cesium";
const ds = await CzmlDataSource.load("/data/vehicle.czml");
viewer.dataSources.add(ds);
await ds.process("/data/vehicle-update.czml");  // append without clearing

GPX

import { GpxDataSource } from "cesium";
const ds = await GpxDataSource.load("/data/trail.gpx");
viewer.dataSources.add(ds);
viewer.zoomTo(ds);

CustomDataSource

import { CustomDataSource, Cartesian3, Color } from "cesium";

const customDs = new CustomDataSource("sensors");
customDs.entities.add({
  position: Cartesian3.fromDegrees(-95, 40),
  point: { pixelSize: 8, color: Color.LIME },
});
viewer.dataSources.add(customDs);
customDs.show = false;  // toggle entire group visibility

Entity Clustering

import { GeoJsonDataSource, Color, VerticalOrigin, PinBuilder } from "cesium";
const ds = await GeoJsonDataSource.load("/data/facilities.geojson");
viewer.dataSources.add(ds);

ds.clustering.enabled = true;
ds.clustering.pixelRange = 40;
ds.clustering.minimumClusterSize = 3;

const pinBuilder = new PinBuilder();
ds.clustering.clusterEvent.addEventListener((entities, cluster) => {
  cluster.label.show = false;
  cluster.billboard.show = true;
  cluster.billboard.verticalOrigin = VerticalOrigin.BOTTOM;
  cluster.billboard.image = pinBuilder.fromText(`${entities.length}`, Color.VIOLET, 48).toDataURL();
});

Parent-Child Visibility

Setting parent.show = false hides all descendants without changing their individual show flags.

const parent = viewer.entities.add({ name: "Group" });
viewer.entities.add({ parent, position: Cartesian3.fromDegrees(-90, 35), point: { pixelSize: 6, color: Color.RED } });
viewer.entities.add({ parent, position: Cartesian3.fromDegrees(-91, 36), point: { pixelSize: 6, color: Color.BLUE } });

parent.show = false;  // both children disappear
parent.show = true;   // both reappear

Entity Description and Custom Properties

// InfoBox HTML: displayed when user clicks the entity
viewer.entities.add({
  name: "Station Alpha",
  position: Cartesian3.fromDegrees(-75.17, 39.95),
  point: { pixelSize: 12, color: Color.CYAN },
  description: `<table class="cesium-infoBox-defaultTable"><tr><th>Status</th><td>Active</td></tr></table>`,
  properties: { population: 500000, category: "metro" },
});
// Read custom properties
// entity.properties.population.getValue()  --> 500000

Export to KML

import { exportKml } from "cesium";

const result = await exportKml({ entities: viewer.entities, kmz: true });
// result.kmz is a Blob; result.kml is a string when kmz: false
const url = URL.createObjectURL(result.kmz);

All 17 Graphics Types

Graphics	Key Properties
PointGraphics	pixelSize, color, outlineColor, outlineWidth
BillboardGraphics	image, scale, rotation, sizeInMeters, heightReference
LabelGraphics	text, font, fillColor, style, showBackground
ModelGraphics	uri, scale, silhouetteColor, runAnimations, colorBlendMode
PolygonGraphics	hierarchy, height, extrudedHeight, material, perPositionHeight
PolylineGraphics	positions, width, material, clampToGround, arcType
EllipseGraphics	semiMajorAxis, semiMinorAxis, rotation, extrudedHeight
RectangleGraphics	coordinates (Rectangle), height, extrudedHeight
BoxGraphics	dimensions (Cartesian3), material, outline
CylinderGraphics	length, topRadius, bottomRadius
EllipsoidGraphics	radii (Cartesian3)
CorridorGraphics	positions, width, cornerType
WallGraphics	positions, minimumHeights, maximumHeights
PolylineVolumeGraphics	positions, shape (Cartesian2[])
PlaneGraphics	plane (Plane), dimensions (Cartesian2)
PathGraphics	resolution, leadTime, trailTime, width
Cesium3DTilesetGraphics	uri

Key Enums

Enum	Values
HeightReference	NONE, CLAMP_TO_GROUND, RELATIVE_TO_GROUND
HorizontalOrigin	LEFT, CENTER, RIGHT
VerticalOrigin	TOP, CENTER, BOTTOM, BASELINE
LabelStyle	FILL, OUTLINE, FILL_AND_OUTLINE
ColorBlendMode	HIGHLIGHT, REPLACE, MIX
ShadowMode	DISABLED, ENABLED, CAST_ONLY, RECEIVE_ONLY

Performance Tips

1. Use suspendEvents()/resumeEvents() when bulk-adding entities to batch change notifications.
2. Prefer constant properties for static data -- CesiumJS optimizes non-changing entities.
3. Use DistanceDisplayCondition to hide entities beyond a useful range.
4. Switch to Primitives for 10k+ static shapes; Primitives avoid per-entity overhead.
5. Enable clustering on DataSources with many point-like entities.
6. Set disableDepthTestDistance on billboards/labels to prevent terrain occlusion.
7. Minimize outlines on ground-clamped polygons -- extra rendering passes required.
8. Use clampToGround only when needed -- requires terrain-conforming subdivision.
9. Batch CZML updates with process() to append, not load() which replaces all.
10. Cache PinBuilder canvases -- reuse results to avoid regenerating identical images.

See Also

• cesiumjs-time-properties -- SampledProperty, CallbackProperty, MaterialProperty types for time-dynamic entity attributes
• cesiumjs-primitives -- Low-level Primitive API for performance-critical static geometry (*Geometry classes)
• cesiumjs-interaction -- ScreenSpaceEventHandler, Scene.pick, entity selection and hover patterns