LineOfSightLayer | References | ArcGIS Maps SDK for JavaScript

import LineOfSightLayer from "@arcgis/core/layers/LineOfSightLayer.js";

Inheritance:: LineOfSightLayer→Layer→Accessor

Since: ArcGIS Maps SDK for JavaScript 4.24

The line of sight layer enables the creation and display of visibility analysis where a line of sight is computed from a single observer position towards a set of targets. The results are visualized in a 3D SceneView.

It can be grouped with other layers, and when a LayerList widget or Layer List component is used, the line of sight layer appears in the list. It can be persisted in a WebScene.

The line of sight can be created interactively or added programmatically to a LineOfSightAnalysis object, which is then set as the layer's analysis.

// create line of sight analysis
const lineOfSightAnalysis = new LineOfSightAnalysis({
  observer: new LineOfSightAnalysisObserver({ position: new Point({ }) }),
  targets:[
    new LineOfSightAnalysisTarget({ position: new Point({ }) })
  ]
});

// Create the layer with the analysis.
const lineOfSightLayer = new LineOfSightLayer({
  analysis: lineOfSightAnalysis
});

// add to the map
view.map.add(lineOfSightLayer);

Use the LineOfSightLayerView to access analysis results or to edit existing observer and targets interactively.

// wait for the view to not be updating to ensure we get the latest results
await reactiveUtils.whenOnce(() => !view.updating);

// retrieve the results from the layer view
const lineOfSightLayerView = await view.whenLayerView(lineOfSightLayer);
const results = lineOfSightLayerView.results;

// enable editing existing analysis interactively
lineOfSightLayerView.interactive = true;

To create lines of sight interactively, use the LineOfSightLayerView.place() method.

const abortController = new AbortController();

try {
  await lineOfSightLayerView.place({ signal: abortController.signal });
} catch (error) {
  if (error.name === "AbortError") {
    console.log("Placement operation was cancelled.");
  }
}

// cancel the placement operation at some later point
abortController.abort();

If the observer position or target position have z-values then these will be treated as absolute values, otherwise the points will be aligned to the ground.

Known Limitations

This layer is only supported in a 3D SceneView. The results of the tool vary depending on the zoom level, as changes in zoom level affect the level of detail (LOD) of the scene geometry.

See also

Constructors

Constructor

Parameters

Parameter	Type	Description	Required
properties	`LineOfSightLayerProperties`

See the properties table for a list of all the properties that may be passed into the constructor.

Example

const lineOfSightLayer = new LineOfSightLayer();

Properties

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

Property	Type	Class
`analysis`	`LineOfSightAnalysis`
`declaredClass` readonly inherited	`string`	Accessor
`fullExtent` readonly	`Extent \| null \| undefined`
`id` inherited	`string`	Layer
`listMode` inherited	`LayerListMode`	Layer
`loaded` readonly inherited	`boolean`	Layer
`loadError` readonly inherited	`EsriError \| null \| undefined`	LoadableMixin
`loadStatus` readonly inherited	`"not-loaded" \| "loading" \| "failed" \| "loaded"`	LoadableMixin
`loadWarnings` readonly inherited	`any[]`	LoadableMixin
`observer`	`LineOfSightAnalysisObserver \| null \| undefined`
`opacity` inherited	`number`	Layer
`parent` inherited	`Map \| Basemap \| Ground \| GroupLayer \| CatalogDynamicGroupLayer \| CatalogLayer \| null \| undefined`	Layer
`persistenceEnabled` inherited	`boolean`	OperationalLayer
`spatialReference` readonly	`SpatialReference`
`targets`	`Collection<LineOfSightAnalysisTarget> \| null \| undefined`
`title` inherited	`string \| null \| undefined`	Layer
`type` readonly	`"line-of-sight"`
`uid` readonly inherited	`string`	IdentifiableMixin
`visibilityTimeExtent` inherited	`TimeExtent \| null \| undefined`	Layer
`visible` inherited	`boolean`	Layer

analysis

autocast Property

Type: LineOfSightAnalysis

The LineOfSightAnalysis associated with the layer. Assigning a null value will create a new empty analysis.

declaredClass

readonlyinherited Property

Type: string

Inherited from: Accessor

The name of the class. The declared class name is formatted as esri.folder.className.

fullExtent

readonly Property

Type: Extent | null | undefined

The full extent of the layer computed from the observer and targets. The returned extent has Z values only if the observer and all targets have absolute Z values.

Example

// Once the layer loads, set the view's extent to the layer's full extent
layer.when(function(){
  view.extent = layer.fullExtent;
});

id

inherited Property

Type: string

Inherited from: Layer

The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.

listMode

inherited Property

Type: LayerListMode

Inherited from: Layer

Indicates how the layer should display in the Layer List component. The possible values are listed below.

Value	Description
show	The layer is visible in the table of contents.
hide	The layer is hidden in the table of contents.
hide-children	If the layer is a GroupLayer, BuildingSceneLayer, KMLLayer, MapImageLayer, SubtypeGroupLayer, TileLayer, or WMSLayer, hide the children layers from the table of contents.

Default value: "show"

loaded

readonlyinherited Property

Type: boolean

Inherited from: Layer

Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.

Default value: false

loadError

readonlyinherited Property

Type: EsriError | null | undefined

Inherited from: LoadableMixin

The Error object returned if an error occurred while loading.

loadStatus

readonlyinherited Property

Type: "not-loaded" | "loading" | "failed" | "loaded"

Inherited from: LoadableMixin

Represents the status of a load() operation.

Value	Description
not-loaded	The object's resources have not loaded.
loading	The object's resources are currently loading.
loaded	The object's resources have loaded without errors.
failed	The object's resources failed to load. See loadError for more details.

Default value: "not-loaded"

loadWarnings

readonlyinherited Property

Type: any[]

Inherited from: LoadableMixin

A list of warnings which occurred while loading.

observer

autocast Property

Type: LineOfSightAnalysisObserver | null | undefined

The observer defines the point from which the line of sight analysis is performed.

The observer position must be set before the layer can be saved to a WebScene.

This property is an alias to the same property on the analysis object held by this layer.

opacity

inherited Property

Type: number

Inherited from: Layer

The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.

Known Limitations

In a 3D SceneView, modifying opacity is not supported for DimensionLayer, GaussianSplatLayer, IntegratedMesh3DTilesLayer, IntegratedMeshLayer, LineOfSightLayer, PointCloudLayer, ViewshedLayer, and VoxelLayer.

Default value: 1

Example

// Makes the layer 50% transparent
layer.opacity = 0.5;

parent

inherited Property

Type: Map | Basemap | Ground | GroupLayer | CatalogDynamicGroupLayer | CatalogLayer | null | undefined

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.27

The parent to which the layer belongs.

persistenceEnabled

inherited Property

Type: boolean

Inherited from: OperationalLayer

Since: ArcGIS Maps SDK for JavaScript 4.28

Enable persistence of the layer in a WebMap or WebScene.

Default value: true

spatialReference

readonly Property

Type: SpatialReference

The spatial reference of the layer. The spatial reference is derived from the observer.

targets

autocast Property

Type: Collection<LineOfSightAnalysisTarget> | null | undefined

Target locations. A list of points to look at from the observer.

This property is an alias to the same property on the analysis object held by this layer.

title

inherited Property

Type: string | null | undefined

Inherited from: Layer

The title of the layer used to identify it in places such as the Layer List component.

If the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

type

readonly Property

Type: "line-of-sight"

The layer type provides a convenient way to check the type of the layer without the need to import specific layer modules.

uid

readonlyinherited Property

Type: string

Inherited from: IdentifiableMixin

Since: ArcGIS Maps SDK for JavaScript 4.33

An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.

visibilityTimeExtent

autocast inherited Property

Type: TimeExtent | null | undefined

Inherited from: Layer

Since: ArcGIS Maps SDK for JavaScript 4.30

Specifies a fixed time extent during which a layer should be visible. This property can be used to configure a layer that does not have time values stored in an attribute field to work with time. Once configured, the TimeSlider widget will display the layer within the set time extent. In the case that only one of the TimeExtent.start or TimeExtent.end date values are available, the layer remains visible indefinitely in the direction where there is no time value.

Aerial imagery can capture seasonal variations in vegetation, water bodies, and land use patterns. For example, in agricultural regions, aerial imageries taken during different growing seasons provide insights into crop health and productivity. Defining a fixed time extent on imageries from specific time periods provides temporal context and facilitates focused analysis based on specific time periods or events.

See also

Sample - GraphicsLayer with visibilityTimeExtent

visible

inherited Property

Type: boolean

Inherited from: Layer

Indicates if the layer is visible in the View. When false, the layer may still be added to a Map instance that is referenced in a view, but its features will not be visible in the view.

Default value: true

Example

// The layer is no longer visible in the view
layer.visible = false;

// Watch for changes in the layer's visibility
// and set the visibility of another layer when it changes
reactiveUtils.watch(
  () => layer.visible,
  (visible) => {
    if (visible) {
      anotherLayer.visible = true;
    } else {
      anotherLayer.visible = false;
    }
  }
);

Methods

Method	Signature	Class
`fromArcGISServerUrl` inherited static	`fromArcGISServerUrl(params: string \| FromArcGISServerUrlParameters): Promise<Layer>`	Layer
`fromPortalItem` inherited static	`fromPortalItem(params: LayerFromPortalItemParameters): Promise<Layer>`	Layer
`cancelLoad` inherited	`cancelLoad(): this`	LoadableMixin
`createLayerView` inherited	`createLayerView<T extends LayerView = LayerView>(view: View<T>, options?: AbortOptions): Promise<T>`	Layer
`destroy` inherited	`destroy(): void`	Layer
`emit` inherited	`emit<Type extends EventNames<this>>(type: Type, event?: this["@eventTypes"][Type]): boolean`	EventedMixin
`fetchAttributionData` inherited	`fetchAttributionData(): Promise<any>`	Layer
`hasEventListener` inherited	`hasEventListener<Type extends EventNames<this>>(type: Type): boolean`	EventedMixin
`isFulfilled` inherited	`isFulfilled(): boolean`	EsriPromiseMixin
`isRejected` inherited	`isRejected(): boolean`	EsriPromiseMixin
`isResolved` inherited	`isResolved(): boolean`	EsriPromiseMixin
`load` inherited	`load(options?: AbortOptions \| null \| undefined): Promise<this>`	LoadableMixin
`on` inherited	`on<Type extends EventNames<this>>(type: Type, listener: EventedCallback<this["@eventTypes"][Type]>): ResourceHandle`	EventedMixin
`when` inherited	`when<TResult1 = this, TResult2 = never>(onFulfilled?: OnFulfilledCallback<this, TResult1> \| null \| undefined, onRejected?: OnRejectedCallback<TResult2> \| null \| undefined): Promise<TResult1 \| TResult2>`	EsriPromiseMixin

fromArcGISServerUrl

inheritedstatic Method

Signature: fromArcGISServerUrl (params: string | FromArcGISServerUrlParameters): Promise<Layer>

Inherited from: Layer

Creates a new layer instance from an ArcGIS Server URL. Depending on the URL, the returned layer type may be a BuildingSceneLayer, CatalogLayer, ElevationLayer, FeatureLayer, GroupLayer, ImageryLayer, ImageryTileLayer, IntegratedMeshLayer, KnowledgeGraphLayer, MapImageLayer, OrientedImageryLayer, PointCloudLayer, SceneLayer, StreamLayer, SubtypeGroupLayer, TileLayer, or VideoLayer.

This is useful when you work with various ArcGIS Server URLs, but you don't necessarily know which layer type(s) they create. This method creates the appropriate layer type for you. In case of a feature service or a scene service, when the URL points to the service and the service has multiple layers, the returned promise will resolve to a GroupLayer.

Beginning with version 4.17, it is possible to load tables from hosted feature services. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific URL types.

URL	Returns
Feature service with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature service with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature service with more than one layer(s)/table(s)	GroupLayer with layers and tables.
Layers with type other than "Feature Layer" are discarded, e.g. Utility Network Layers	N/A

See also

FeatureLayer.isTable

Parameters

Parameter	Type	Description	Required
params	`string \| FromArcGISServerUrlParameters`	Input parameters for creating the layer.

Returns: Promise<Layer>
Returns a promise that resolves to the new Layer instance.

Examples

// This snippet shows how to add a feature layer from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl,
  properties: {
    // set any layer properties here
    popupTemplate: new PopupTemplate()
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});

// This snippet shows how to add a table from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl
}).then(function(layer){
  // Load the table before it can be used
  layer.load().then(function() {
    // Check that it is the right type
    if (layer.isTable) {
      // Add table to map's tables collection
      map.tables.add(layer);
    }
  });
});

fromPortalItem

inheritedstatic Method

Signature: fromPortalItem (params: LayerFromPortalItemParameters): Promise<Layer>

Inherited from: Layer

Creates a new layer instance of the appropriate layer class from an ArcGIS Online or ArcGIS Enterprise portal item. If the item points to a feature service with multiple layers, then a GroupLayer is created. If the item points to a service with a single layer, then it resolves to a layer of the same type of class as the service.

Note

At version 4.29, MediaLayer can be loaded from portal items.
At version 4.28, GroupLayer and OrientedImageryLayer can be loaded from portal items.
At version 4.25, CSVLayer and GeoJSONLayer can be loaded from CSV and GeoJSON portal items respectively.
At version 4.17, it is possible to load tables from feature service items hosted in ArcGIS Online and ArcGIS Enterprise. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific item types.

Item(s)	Returns
Feature service with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature service with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature service with more than one layer(s)/table(s)	GroupLayer with layers and tables.
Feature collection with one layer	FeatureLayer where FeatureLayer.isTable returns `false`.
Feature collection with one table	FeatureLayer where FeatureLayer.isTable returns `true`.
Feature collection with more than one layer(s)/table(s)	GroupLayer with layers and tables.

Known Limitations

This method does not currently work with OGCFeatureServer portal items.

See also

Parameters

Parameter	Type	Description	Required
params	`LayerFromPortalItemParameters`	The parameters for loading the portal item.

Returns: Promise<Layer>
Returns a promise which resolves to the new layer instance.

Examples

// Create a layer from a specified portal item and add to the map
Layer.fromPortalItem({
  portalItem: {  // autocasts new PortalItem()
    id: "8444e275037549c1acab02d2626daaee"
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});

// Create a table from a specified portal item and add it to the map's tables collection
Layer.fromPortalItem({
  portalItem: { // autocasts new PortalItem()
    id: "123f4410054b43d7a0bacc1533ceb8dc" // This is a hosted table stored in a feature service
  }
}).then(function(layer) {
  // Necessary to load the table in order for it to be read correctly
  layer.load().then(function() {
    // Confirm this reads as a table
    if (layer.isTable) {
      // Add the new table to the map's table collection
      map.tables.add(layer);
    }
  });
});

cancelLoad

inherited Method

Signature: cancelLoad (): this

Inherited from: LoadableMixin

Cancels a load() operation if it is already in progress.

Returns: this

createLayerView

inherited Method

Signature: createLayerView <T extends LayerView = LayerView>(view: View<T>, options?: AbortOptions): Promise<T>

Type parameters: <T extends LayerView = LayerView>

Inherited from: Layer

Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it. This method is used internally and there is no use case for invoking it directly.

See also

Sample - Custom WebGL layer view

Parameters

Parameter	Type	Description	Required
view	`View`	The parent view.
options	`AbortOptions`	An object specifying additional options. See the object specification table below for the required properties of this object.

Returns: Promise
Resolves with a LayerView instance.

destroy

inherited Method

Signature: destroy (): void

Inherited from: Layer

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer). The layer can no longer be used once it has been destroyed.

The destroyed layer will be removed from its parent object like Map, WebMap, WebScene, Basemap, Ground, or GroupLayer.

See also

Returns: void

emit

inherited Method

Signature: emit <Type extends EventNames<this>>(type: Type, event?: this["@eventTypes"][Type]): boolean

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters

Parameter	Type	Description	Required
type	`Type`	The name of the event.
event	`this["@eventTypes"][Type]`	The event payload.

Returns: boolean
true if a listener was notified

fetchAttributionData

inherited Method

Signature: fetchAttributionData (): Promise<any>

Inherited from: Layer

Fetches custom attribution data for the layer when it becomes available.

Returns: Promise<any>
Resolves to an object containing custom attribution data for the layer.

hasEventListener

inherited Method

Signature: hasEventListener <Type extends EventNames<this>>(type: Type): boolean

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameters

Parameter	Type	Description	Required
type	`Type`	The name of the event.

Returns: boolean
Returns true if the class supports the input event.

isFulfilled

inherited Method

Signature: isFulfilled (): boolean

Inherited from: EsriPromiseMixin

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns: boolean
Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected

inherited Method

Signature: isRejected (): boolean

Inherited from: EsriPromiseMixin

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns: boolean
Indicates whether creating an instance of the class has been rejected.

isResolved

inherited Method

Signature: isResolved (): boolean

Inherited from: EsriPromiseMixin

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns: boolean
Indicates whether creating an instance of the class has been resolved.

load

inherited Method

Signature: load (options?: AbortOptions | null | undefined): Promise<this>

Inherited from: LoadableMixin

Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.

This method must be called by the developer when accessing a resource that will not be loaded in a View.

The load() method only triggers the loading of the resource the first time it is called. The subsequent calls return the same promise.

It's possible to provide a signal to stop being interested into a Loadable instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad() can abort it.

Parameters

Parameter	Type	Description	Required
options	`AbortOptions \| null \| undefined`	Additional options.

Returns: Promise<this>
Resolves when the resources have loaded.

on

inherited Method

Signature: on <Type extends EventNames<this>>(type: Type, listener: EventedCallback<this["@eventTypes"][Type]>): ResourceHandle

Type parameters: <Type extends EventNames<this>>

Inherited from: EventedMixin

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

Parameter	Type	Description	Required
type	`Type`	An event or an array of events to listen for.
listener	`EventedCallback<this["@eventTypes"][Type]>`	The function to call when the event fires.

Returns

ResourceHandle

Returns an event handler with a remove() method that should be called to stop listening for the event(s).

Property	Type	Description
remove	Function	When called, removes the listener from the event.

Example

view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

when

inherited Method

Signature: when <TResult1 = this, TResult2 = never>(onFulfilled?: OnFulfilledCallback<this, TResult1> | null | undefined, onRejected?: OnRejectedCallback<TResult2> | null | undefined): Promise<TResult1 | TResult2>

Type parameters: <TResult1 = this, TResult2 = never>

Inherited from: EsriPromiseMixin

when() may be leveraged once an instance of the class is created. This method takes two input parameters: an onFulfilled function and an onRejected function. The onFulfilled executes when the instance of the class loads. The onRejected executes if the instance of the class fails to load.

Parameters

Parameter	Type	Description	Required
onFulfilled	`OnFulfilledCallback<this, TResult1> \| null \| undefined`	The function to call when the promise resolves.
onRejected	`OnRejectedCallback \| null \| undefined`	The function to execute when the promise fails.

Returns: Promise<TResult1 | TResult2>
Returns a new promise for the result of onFulfilled that may be used to chain additional functions.

Example

// Although this example uses MapView, any class instance that is a promise may use when() in the same way
let view = new MapView();
view.when(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

Events

Name	Type
`layerview-create` inherited	CustomEvent<LayerLayerviewCreateEvent>
`layerview-create-error` inherited	CustomEvent<LayerLayerviewCreateErrorEvent>
`layerview-destroy` inherited	CustomEvent<LayerLayerviewDestroyEvent>

layerview-create

inherited Event

layerview-create: CustomEvent<LayerLayerviewCreateEvent>

Inherited from: Layer

Fires after the layer's LayerView is created and rendered in a view.

See also

View.whenLayerView()

Example

// This function will fire each time a layer view is created for this
// particular view.
layer.on("layerview-create", function(event){
  // The LayerView for the layer that emitted this event
  event.layerView;
});

layerview-create-error

inherited Event

layerview-create-error: CustomEvent<LayerLayerviewCreateErrorEvent>

Inherited from: Layer

Fires when an error emits during the creation of a LayerView after a layer has been added to the map.

See also

View.whenLayerView()

Example

// This function fires when an error occurs during the creation of the layer's layerview
layer.on("layerview-create-error", function(event) {
  console.error("LayerView failed to create for layer with the id: ", layer.id, " in this view: ", event.view);
});

layerview-destroy

inherited Event

layerview-destroy: CustomEvent<LayerLayerviewDestroyEvent>

Inherited from: Layer

Fires after the layer's LayerView is destroyed and no longer renders in a view.