LineOfSightLayer

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

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
LineOfSightAnalysismore details

The LineOfSightAnalysis associated with the layer.

more detailsLineOfSightLayer
Stringmore details

The name of the class.

more detailsAccessor
Extentmore details

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

more detailsLineOfSightLayer
Stringmore details

The unique ID assigned to the layer.

more detailsLayer
Stringmore details

Indicates how the layer should display in the LayerList widget.

more detailsLayer
Booleanmore details

Indicates whether the layer's resources have loaded.

more detailsLayer
Errormore details

The Error object returned if an error occurred while loading.

more detailsLayer
Stringmore details

Represents the status of a load operation.

more detailsLayer
Object[]more details

A list of warnings which occurred while loading.

more detailsLayer
LineOfSightAnalysisObservermore details

Observer location.

more detailsLineOfSightLayer
SpatialReferencemore details

The spatial reference of the layer.

more detailsLineOfSightLayer
Collection<LineOfSightAnalysisTarget>more details

Target locations.

more detailsLineOfSightLayer
Stringmore details

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

more detailsLayer
Stringmore details For LineOfSightLayer the type is always "line-of-sight". more detailsLineOfSightLayer
Booleanmore details

Indicates if the layer is visible in the View.

more detailsLayer

Property Details

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

declaredClass Stringreadonly inherited

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

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.

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

listMode String inherited

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 Booleanreadonly inherited

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

Default Value:false
loadError Errorreadonly inherited

The Error object returned if an error occurred while loading.

Default Value:null
loadStatus Stringreadonly inherited

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 Object[]readonly inherited

A list of warnings which occurred while loading.

Observer location. This is the point from which line of sight analysis is performed.

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

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.

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 Stringreadonly

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

visible Boolean inherited

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
more details

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

more detailsLayer
Promise<LayerView>more details

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.

more detailsLayer
more details

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

more detailsLayer
Booleanmore details

Emits an event on the instance.

more detailsLayer
Promise<Object>more details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Promisemore details

Loads the resources referenced by this class.

more detailsLayer
Objectmore details

Registers an event handler on the instance.

more detailsLayer
Promisemore details

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

more detailsLayer

Method Details

cancelLoad()inherited

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

createLayerView(view, options){Promise<LayerView>}inherited

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.
See also:
destroy()inherited

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:
emit(type, event){Boolean}inherited

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(){Promise<Object>}inherited

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(type){Boolean}inherited

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.
isFulfilled(){Boolean}inherited

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(){Boolean}inherited

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(){Boolean}inherited

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(signal){Promise}inherited

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(type, listener){Object}inherited

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);
});
when(callback, errback){Promise}inherited

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}
more details

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

more details Layer
{view: View,error: Error}
more details

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

more details Layer
{view: View,layerView: LayerView}
more details

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

more details Layer

Event Details

layerview-createinherited

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-errorinherited

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-destroyinherited

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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