ESM: import BaseElevationLayer from "@arcgis/core/layers/BaseElevationLayer.js";
CDN: const BaseElevationLayer = await $arcgis.import("@arcgis/core/layers/BaseElevationLayer.js");
Class: @arcgis/core/layers/BaseElevationLayer
Since: ArcGIS Maps SDK for JavaScript 4.4
BaseElevationLayer is intended to be extended for creating custom elevation layers. You create a custom ElevationLayer by calling createSubclass() on the BaseElevationLayer.
If the new layer needs to fetch and prepare resources, you can initialize properties asynchronously prior to loading the layer. This is handled in the load() method. This method is called once, either by you or by the view, when the layer is about to be displayed. In the body of the method you can call addResolvingPromise() to add a promise that has to be resolved before the layer is considered loaded.
You must overwrite the logic in the fetchTile() method to return the values of the custom elevation data. This can be done to exaggerate actual elevation values or for mapping thematic data as an elevation layer. When transforming the values of the elevation data it is recommended to keep the no data value unchanged.
const ExaggeratedElevationLayer = BaseElevationLayer.createSubclass({
load: function() {
// add loadable dependencies here and include
// their returned promises in the
// addResolvingPromise() method
this._elevation = new ElevationLayer({
url: "//elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"
});
this.addResolvingPromise(this._elevation.load());
},
fetchTile: function(level, row, col, options) {
// must resolve to an object with the following properties:
// values <number[]>: an array of elevation values for each pixel
// width <number>: the width of the tile in pixels
// height <number>: the height of the tile in pixels
// noDataValue <number>: value of pixels where no elevation data is present
return this._elevation.fetchTile(level, row, col, options).then(function(data) {
let exaggeration = this.exaggeration;
// `data` is an object that contains the width of the tile in pixels,
// the height of the tile in pixels, and the values of each pixel
for (let i = 0; i < data.values.length; i++) {
// each value represents an elevation sample for the
// given pixel position in the tile
// check if the value is a no data value
if (data.values[i] !== data.noDataValue) {
// multiply the elevation value by the exaggeration value
data.values[i] *= exaggeration;
}
}
return data;
}.bind(this))
}
});
Once the layer is created, you must add it to the layers of the Map.ground property and add the map to a SceneView instance.
let map = new Map({
basemap: "satellite",
ground: {
layers: [ new ExaggeratedElevationLayer() ]
}
});
sceneView.map = map;
Show inherited properties Hide inherited properties
Property DetailsInherited
Property declaredClass Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.
The name of the class. The declared class name is formatted as esri.folder.className.
The full extent of the layer. By default, this is worldwide. This property may be used to set the extent of the view to match a layer's extent so that its features appear to fill the view. See the sample snippet below.
Example
// Once the layer loads, set the view's extent to the layer's fullextent
layer.when(function(){
view.extent = layer.fullExtent;
});Inherited
Property id String
The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.
Inherited
Property listMode String
Indicates how the layer should display in the LayerList widget. The possible values are listed below.
Possible Values:"show" |"hide" |"hide-children"
The Error object returned if an error occurred while loading.
Inherited
Property loadStatus Stringreadonly
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"
Inherited
Property loadWarnings Object[]readonly
A list of warnings which occurred while loading.
Inherited
Property loaded Booleanreadonly
Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.
Inherited
Property opacity Number
The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.
Example
// Makes the layer 50% transparent
layer.opacity = 0.5;Since: ArcGIS Maps SDK for JavaScript 4.27 Layer since 4.0, parent added at 4.27.
The parent to which the layer belongs.
Inherited
Property persistenceEnabled Booleanreadonly
Since: ArcGIS Maps SDK for JavaScript 4.28 Layer since 4.0, persistenceEnabled added at 4.28.
When true, the layer can be persisted. This property only has an effect for layers that are part of the WebMap or WebScene spec.
The spatial reference of the layer.
The tiling scheme information for the 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.
Inherited
Property uid Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.33 Layer since 4.0, uid added at 4.33.
An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.
Since: ArcGIS Maps SDK for JavaScript 4.30 Layer since 4.0, visibilityTimeExtent added at 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 start or 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.
Inherited
Property visible Boolean
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.
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;
}
}
);Show inherited methods Hide inherited methods
Method DetailsInherited
Method addHandles(handleOrHandles, groupKey)
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
Handles marked for removal once the object is destroyed.
groupKey *
optionalKey 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.
addResolvingPromise(promiseToLoad)
Adds a promise to the layer's loadable chain. This is typically used in the load() method to ensure that all loadable resources required for the layer to function are loaded prior to this layer resolving and becoming loaded.
Parameter
promiseToLoad Promise
A promise that must resolve for the layer to resolve and move from the loading status to being loaded.
Example
// the _elevationLayer must load() prior to the ExaggeratedElevationLayer
// resolving and moving to the "loaded" status
const ExaggeratedElevationLayer = BaseElevationLayer.createSubclass({
load: function() {
this._elevationLayer = new ElevationLayer({
url: "//elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"
});
this.addResolvingPromise(this._elevationLayer.load());
}
});Inherited
Method cancelLoad()
Cancels a load() operation if it is already in progress.
createElevationSampler(extent, options){Promise<ElevationSampler>}
Since: ArcGIS Maps SDK for JavaScript 4.12 BaseElevationLayer since 4.4, createElevationSampler added at 4.12.
Creates an elevation sampler for the given Extent by querying the service layer for elevation data and caching it so values may be sampled quickly afterwards. The resolution of the cached data can be set using the demResolution option. In many cases, auto demResolution can be used to get high quality elevation samples without the need to know exactly where the data in the service is located. This is particularly useful for services which combine elevation data from many sources (such as the world elevation service). If more control, or higher quality samples are required, use either finest-contiguous or a fixed {number} resolution.
Parameters
Specification
The extent for which to create the sampler.
optionalAdditional query options. See the table below.
Specification
optionalDefault Value: auto
Controls the horizontal resolution (cell size) in meters from which elevation data is sampled (defaults to auto). See ElevationLayer.queryElevation for more details.
Default Value: 0
The value to use when there is no data available.
Returns
Inherited
Method createLayerView(view, options){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. This method is used internally and there is no use case for invoking it directly.
Parameters
view *
The parent view.
optionalAn object specifying additional options. See the object specification table below for the required properties of this object.
Returns
Inherited
Method destroy()
Since: ArcGIS Maps SDK for JavaScript 4.17 Layer since 4.0, destroy added at 4.17.
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.
Inherited
Method emit(type, event){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.5 Layer since 4.0, emit added at 4.5.
Emits an event on the instance. This method should only be used when creating subclasses of this class.
Parameters
The name of the event.
optionalThe event payload.
Returns
Type Description Booleantrue if a listener was notified
Inherited
Method fetchAttributionData(){Promise<Object>}
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.Parameters
Specification
The level of detail of the tile to fetch.
The row (y) position of the tile to fetch.
The column (x) position of the tile to fetch.
optionalOptional settings for the tile request.
Specification
optionalThe value representing pixels in the tile that don't contain an elevation value.
optionalAn AbortSignal to abort the request. When overriding fetchTile, signal should be handled, for example by passing it on to request or by aborting pending operations. An aborted call to fetchTile should reject its returned promise with an error named AbortError. See also AbortController.
Returns
getTileBounds(level, row, column, out){Number[]}
Returns the bounds of the tile as an array of four numbers that can be readily converted to an Extent object. See the table in the returns section below for more details about the values returned by this method.
This function can be used inside fetchTile() so you can get the bounds of the current tile, convert it to an extent object, and request the desired data for the given extent. See the Custom ElevationLayer: Thematic data as elevation sample for an example of how this method works.
Parameters
The level of detail (LOD) of the tile.
The tile's row (y) position in the dataset.
The tiles column (x) position in the dataset.
optionalArray for storing the tile bounds or extent.
Returns
Type Description Number[] Returns an array representing the tile bounds or extent. The array has four items, each representing one bound of the extent. The values of each item are described in the table below. Index Value 0 Minimum x-value 1 Minimum y-value 2 Maximum x-value 3 Maximum y-valueInherited
Method hasEventListener(type){Boolean}
Indicates whether there is an event listener on the instance that matches the provided event name.
Returns
Type Description Boolean Returns true if the class supports the input event.Inherited
Method hasHandles(groupKey){Boolean}
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 *
optionalA group key.
Returns
Type Description Boolean Returnstrue 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");
}Inherited
Method isFulfilled(){Boolean}
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).Inherited
Method isRejected(){Boolean}
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.Inherited
Method isResolved(){Boolean}
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.Inherited
Method load(options){Promise}
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
optionalAdditional options.
Specification
optionalSignal 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.Inherited
Method on(type, listener){Object}
Registers an event handler on the instance. Call this method to hook an event with a listener.
Returns
Type Description Object Returns an event handler with aremove() 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);
});Since: ArcGIS Maps SDK for JavaScript 4.12 BaseElevationLayer since 4.4, queryElevation added at 4.12.
Queries the service layer for elevation values for the given geometry. The returned result contains a copy of the geometry with z-values sampled from elevation data from the service. The resolution from which the elevation is queried can be set using the demResolution option. In many cases, auto demResolution can be used to get high quality elevation samples without the need to know exactly where the data in the service is located. This is particularly useful for services which combine elevation data from many sources (such as the world elevation service). If more control, or higher quality samples are required, use either finest-contiguous or a fixed {number} resolution.
Parameters
Specification
geometry Point|Multipoint|PolylineThe geometry to use for sampling elevation data.
options Object optionalAdditional query options. See the table below.
Specification
demResolution Number|String optionalDefault Value: auto
Controls the horizontal resolution (cell size) in meters from which elevation data is sampled (defaults to auto). See the table below for more details on the different settings.
auto Automatically chooses an appropriate resolution for each coordinate of the input geometry. The current implementation will try to use the finest available resolution given that the total required number of tile requests does not exceed a certain maximum amount (currently 20). Note that this may result in values being sampled from different resolutions. finest-contiguous Sample elevation from the finest available resolution (cell size) across the entire geometry. {number} Sample elevation from the resolution closest to the specified resolution (in meters). returnSampleInfo Boolean optional
Default Value: false
Indicates whether to return additional sample information for each coordinate.
noDataValue Number optionalDefault Value: 0
The value to use when there is no data available.
Returns
Type Description Promise<ElevationQueryResult> Resolves to an object with the sampled geometry, resolution information, and no data value.Inherited
Method removeHandles(groupKey)
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 *
optionalA 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");Inherited
Method when(callback, errback){Promise}
Since: ArcGIS Maps SDK for JavaScript 4.6 Layer since 4.0, when added at 4.6.
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
optionalThe function to call when the promise resolves.
optionalThe function to execute when the promise fails.
Returns
Type Description Promise Returns a new promise for the result ofcallback 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
}); ElevationTileData
Describes elevation contained in the pixels that comprise an elevation tile.
The elevation values of each pixel in the tile.
The width of the tile in pixels.
The height of the tile in pixels.
Indicating the pixel values where no elevation data is present.
Show inherited events Hide inherited events
Event DetailsInherited
Event layerview-create
Fires after the layer's LayerView is created and rendered in a view.
The view in which the layerView was created.
The LayerView rendered in the view representing the layer in layer.
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;
});Inherited
Event layerview-create-error
Fires when an error emits during the creation of a LayerView after a layer has been added to the map.
The view that failed to create a layerview for the layer emitting this event.
An error object describing why the layer view failed to create.
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);
});Inherited
Event layerview-destroy
Fires after the layer's LayerView is destroyed and no longer renders in a view.
The view in which the layerView was destroyed.
The destroyed LayerView representing the layer.
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