LineOfSightLayer

AMD: require(["esri/layers/LineOfSightLayer"], (LineOfSightLayer) => { /* code goes here */ });
ESM: import LineOfSightLayer from "@arcgis/core/layers/LineOfSightLayer.js";
Class: esri/layers/LineOfSightLayer
Inheritance: LineOfSightLayer Layer Accessor
Since: ArcGIS Maps SDK for JavaScript 4.24

LineOfSightLayer computes the line of sight from a single observer position towards a set of targets. The results are visualized in a 3D SceneView.

To display the line of sight between two points, create a new instance of LineOfSightLayer, add it to SceneView.map and set the observer and targets properties.

Use the LineOfSightAnalysisView3D to retrieve analysis results.

// create lineofsight layer
const lineOfSightLayer = new LineOfSightLayer({
  observer: new LineOfSightAnalysisObserver({ position: somePoint }),
  targets:[
    new LineOfSightAnalysisTarget({position: someOtherPoint})
  ]
});

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

// wait for the view to load before checking the result
await reactiveUtils.whenOnce(() => !view.updating);

// retrieve measured results from analysis view
const analysisView = await view.whenAnalysisView(lineOfSightLayer.analysis);
const results = analysisView.results;

Use the LineOfSight widget in order to add interactivity and allow users to change the geometry of the analysis.

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 analysis is only supported in a 3D SceneView.
See also

Constructors

LineOfSightLayer

Constructor
new LineOfSightLayer(properties)
Parameter
properties Object
optional

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

Example
const lineOfSightLayer = new LineOfSightLayer();

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
LineOfSightAnalysis

The LineOfSightAnalysis associated with the layer.

LineOfSightLayer
String

The name of the class.

Accessor
Extent

The full extent of the layer computed from the observer and targets.

LineOfSightLayer
String

The unique ID assigned to the layer.

Layer
String

Indicates how the layer should display in the LayerList widget.

Layer
Boolean

Indicates whether the layer's resources have loaded.

Layer
Error

The Error object returned if an error occurred while loading.

Layer
String

Represents the status of a load operation.

Layer
Object[]

A list of warnings which occurred while loading.

Layer
LineOfSightAnalysisObserver

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

LineOfSightLayer
Map|Basemap|Ground|GroupLayer

The parent to which the layer belongs.

Layer
Boolean

Enable persistence of the layer in a WebMap or WebScene.

LineOfSightLayer
SpatialReference

The spatial reference of the layer.

LineOfSightLayer
Collection<LineOfSightAnalysisTarget>

Target locations.

LineOfSightLayer
String

The title of the layer used to identify it in places such as the LayerList widget.

Layer
String For LineOfSightLayer the type is always "line-of-sight". LineOfSightLayer
Boolean

Indicates if the layer is visible in the View.

Layer

Property Details

analysis

Property
analysis LineOfSightAnalysis

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

declaredClass

Inherited
Property
declaredClass Stringreadonly
Inherited from Accessor

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

fullExtent

Property
fullExtent Extentreadonly

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.

id

Inherited
Property
id 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
listMode String
Inherited from Layer

Indicates how the layer should display in the LayerList widget. 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, TileLayer or WMSLayer, hide the children layers from the table of contents.

Possible Values:"show"|"hide"|"hide-children"

Default Value:"show"

loaded

Inherited
Property
loaded Booleanreadonly
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

Inherited
Property
loadError Errorreadonly
Inherited from Layer

The Error object returned if an error occurred while loading.

Default Value:null

loadStatus

Inherited
Property
loadStatus Stringreadonly
Inherited from Layer

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.

Possible Values:"not-loaded"|"loading"|"failed"|"loaded"

Default Value:not-loaded

loadWarnings

Inherited
Property
loadWarnings Object[]readonly
Inherited from Layer

A list of warnings which occurred while loading.

observer

Property
observer LineOfSightAnalysisObserverautocast

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.

parent

Inherited
Property
parent Map|Basemap|Ground|GroupLayer
Inherited from Layer
Since: ArcGIS Maps SDK for JavaScript 4.27 Layer since 4.0, parent added at 4.27.

The parent to which the layer belongs.

persistenceEnabled

Property
persistenceEnabled Boolean
Since: ArcGIS Maps SDK for JavaScript 4.28 LineOfSightLayer since 4.24, persistenceEnabled added at 4.28.

Enable persistence of the layer in a WebMap or WebScene.

Default Value:true

spatialReference

Property
spatialReference SpatialReferencereadonly

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

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
title String
Inherited from Layer

The title of the layer used to identify it in places such as the LayerList widget.

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

Property
type Stringreadonly

For LineOfSightLayer the type is always "line-of-sight".

visible

Inherited
Property
visible 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;

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

Accessor

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

Layer
Promise<LayerView>

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.

Layer

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer).

Layer
Boolean

Emits an event on the instance.

Layer
Promise<object>

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

Layer
Boolean

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

Layer
Boolean

Returns true if a named group of handles exist.

Accessor
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

Layer
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

Layer
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

Layer
Promise

Loads the resources referenced by this class.

Layer
Object

Registers an event handler on the instance.

Layer

Removes a group of handles owned by the object.

Accessor
Promise

when() may be leveraged once an instance of the class is created.

Layer

Method Details

addHandles

Inherited
Method
addHandles(handleOrHandles, groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 4.25.

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();
Parameters
handleOrHandles WatchHandle|WatchHandle[]

Handles marked for removal once the object is destroyed.

groupKey *
optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

cancelLoad

Inherited
Method
cancelLoad()
Inherited from Layer

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

createLayerView

Inherited
Method
createLayerView(view, options){Promise<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.

Parameters
view *

The parent view.

options Object
optional

An object specifying additional options. See the object specification table below for the required properties of this object.

Specification
signal AbortSignal
optional

A signal to abort the creation of the layerview.

Returns
Type Description
Promise<LayerView> Resolves with a LayerView instance.

destroy

Inherited
Method
destroy()
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.

emit

Inherited
Method
emit(type, event){Boolean}
Inherited from Layer

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

Parameters
type String

The name of the event.

event Object
optional

The event payload.

Returns
Type Description
Boolean true if a listener was notified

fetchAttributionData

Inherited
Method
fetchAttributionData(){Promise<object>}
Inherited from Layer

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

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

hasEventListener

Inherited
Method
hasEventListener(type){Boolean}
Inherited from Layer

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

Parameter
type String

The name of the event.

Returns
Type Description
Boolean Returns true if the class supports the input event.

hasHandles

Inherited
Method
hasHandles(groupKey){Boolean}
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 4.25.

Returns true if a named group of handles exist.

Parameter
groupKey *
optional

A group key.

Returns
Type Description
Boolean Returns true if a named group of handles exist.
Example
// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

isFulfilled

Inherited
Method
isFulfilled(){Boolean}
Inherited from Layer

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
Type Description
Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected

Inherited
Method
isRejected(){Boolean}
Inherited from Layer

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

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been rejected.

isResolved

Inherited
Method
isResolved(){Boolean}
Inherited from Layer

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

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been resolved.

load

Inherited
Method
load(signal){Promise}
Inherited from Layer

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.

Parameter
signal AbortSignal
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns
Type Description
Promise Resolves when the resources have loaded.

on

Inherited
Method
on(type, listener){Object}
Inherited from Layer

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

Parameters

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

Returns
Type Description
Object 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);
});

removeHandles

Inherited
Method
removeHandles(groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 4.25.

Removes a group of handles owned by the object.

Parameter
groupKey *
optional

A group key or an array or collection of group keys to remove.

Example
obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

when

Inherited
Method
when(callback, errback){Promise}
Inherited from Layer

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

Parameters
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

Returns
Type Description
Promise Returns a new promise for the result of callback 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
});

Event Overview

Show inherited events Hide inherited events
Name Type Summary Class
{view: View,layerView: LayerView}

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

Layer
{view: View,error: Error}

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

Layer
{view: View,layerView: LayerView}

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

Layer

Event Details

layerview-create

Inherited
Event
layerview-create
Inherited from Layer

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

Properties
view View

The view in which the layerView was created.

layerView LayerView

The LayerView rendered in the view representing the layer in layer.

See also
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
Inherited from Layer

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

Properties
view View

The view that failed to create a layerview for the layer emitting this event.

error Error

An error object describing why the layer view failed to create.

See also
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
Inherited from Layer

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

Properties
view View

The view in which the layerView was destroyed.

layerView LayerView

The destroyed LayerView representing the layer.

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