require(["esri/layers/BaseElevationLayer"], (BaseElevationLayer) => { /* code goes here */ });
import BaseElevationLayer from "@arcgis/core/layers/BaseElevationLayer.js";
esri/layers/BaseElevationLayer
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;
Property Overview
Name | Type | Summary | Class |
---|---|---|---|
The name of the class. | Accessor | ||
The full extent of the layer. | Layer | ||
The unique ID assigned to the layer. | Layer | ||
Indicates how the layer should display in the LayerList widget. | Layer | ||
Indicates whether the layer's resources have loaded. | Layer | ||
The Error object returned if an error occurred while loading. | Layer | ||
Represents the status of a load operation. | Layer | ||
A list of warnings which occurred while loading. | Layer | ||
The opacity of the layer. | Layer | ||
The parent to which the layer belongs. | Layer | ||
When | Layer | ||
The spatial reference of the layer. | BaseElevationLayer | ||
The tiling scheme information for the layer. | BaseElevationLayer | ||
The title of the layer used to identify it in places such as the LayerList widget. | Layer | ||
For BaseElevationLayer the type is always "base-elevation". | BaseElevationLayer | ||
Specifies a fixed time extent during which a layer should be visible. | Layer | ||
Indicates if the layer is visible in the View. | Layer |
Property Details
-
Inherited from Layer
-
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; });
-
listMode
InheritedPropertylistMode 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"
-
loadStatus
InheritedPropertyloadStatus 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
-
Inherited from Layer
-
A list of warnings which occurred while loading.
-
parent
InheritedPropertyparent Map |Basemap |Ground |GroupLayer |CatalogDynamicGroupLayer |CatalogLayer
Inherited from LayerSince: ArcGIS Maps SDK for JavaScript 4.27Layer since 4.0, parent added at 4.27. -
The parent to which the layer belongs.
-
persistenceEnabled
InheritedPropertypersistenceEnabled Boolean
Inherited from LayerSince: ArcGIS Maps SDK for JavaScript 4.28Layer 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.- Default Value:false
-
spatialReference
spatialReference SpatialReferenceautocast
-
The spatial reference of the layer.
- Default Value:SpatialReference.WebMercator
-
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
type Stringreadonly
-
For BaseElevationLayer the type is always "base-elevation".
-
visibilityTimeExtent
InheritedPropertyvisibilityTimeExtent TimeExtent |null |undefinedautocast
Inherited from LayerSince: ArcGIS Maps SDK for JavaScript 4.30Layer 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.
- Default Value:null
- See also
-
visible
InheritedPropertyvisible 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
Name | Return Type | Summary | Class |
---|---|---|---|
Adds one or more handles which are to be tied to the lifecycle of the object. | Accessor | ||
Adds a promise to the layer's loadable chain. | BaseElevationLayer | ||
Cancels a load() operation if it is already in progress. | Layer | ||
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. | BaseElevationLayer | ||
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 | ||
Emits an event on the instance. | Layer | ||
Fetches custom attribution data for the layer when it becomes available. | Layer | ||
Fetches a tile at the given level, row, and column present in the view. | BaseElevationLayer | ||
Returns the bounds of the tile as an array of four numbers that can be readily converted to an Extent object. | BaseElevationLayer | ||
Indicates whether there is an event listener on the instance that matches the provided event name. | Layer | ||
Returns true if a named group of handles exist. | Accessor | ||
| Layer | ||
| Layer | ||
| Layer | ||
Loads the resources referenced by this class. | Layer | ||
Registers an event handler on the instance. | Layer | ||
Queries the service layer for elevation values for the given geometry. | BaseElevationLayer | ||
Removes a group of handles owned by the object. | Accessor | ||
| Layer |
Method Details
-
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25Accessor 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();
ParametershandleOrHandles WatchHandle|WatchHandle[]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
addResolvingPromise(promiseToLoad){Promise}
-
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.
ParameterReturnsType Description Promise Resolves when the given promise
resolves.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()); } });
-
createElevationSampler
createElevationSampler(extent, options){Promise<ElevationSampler>}
Since: ArcGIS Maps SDK for JavaScript 4.12BaseElevationLayer 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 eitherfinest-contiguous
or a fixed{number}
resolution.ParametersSpecificationextent ExtentThe extent for which to create the sampler.
options ObjectoptionalAdditional query options. See the table below.
Specificationoptional Default Value: autoControls the horizontal resolution (cell size) in meters from which elevation data is sampled (defaults to
auto
). See ElevationLayer for more details.noDataValue NumberoptionalDefault Value: 0The value to use when there is no data available.
ReturnsType Description Promise<ElevationSampler> An elevation sampler.
-
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.
Parametersview *The parent view.
options ObjectoptionalAn object specifying additional options. See the object specification table below for the required properties of this object.
Specificationsignal AbortSignaloptionalA signal to abort the creation of the layerview.
Returns- See also
-
Inherited from Layer
Since: ArcGIS Maps SDK for JavaScript 4.17Layer 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.
-
emit
InheritedMethodemit(type, event){Boolean}
Inherited from LayerSince: ArcGIS Maps SDK for JavaScript 4.5Layer 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.
ReturnsType Description Boolean true
if a listener was notified
-
Inherited from Layer
-
Fetches custom attribution data for the layer when it becomes available.
Returns
-
fetchTile
fetchTile(level, row, column, options){Promise<ElevationTileData>}
-
Fetches a tile at the given level, row, and column present in the view. This method must be overwritten to display custom elevation values in the Map.ground. Note that this method must return a promise that resolves to an object with the properties defined in ElevationTileData.
See the following samples for examples of how to overwrite this method:
ParametersSpecificationlevel NumberThe level of detail of the tile to fetch.
row NumberThe row (y) position of the tile to fetch.
column NumberThe column (x) position of the tile to fetch.
options ObjectoptionalOptional settings for the tile request.
SpecificationnoDataValue NumberoptionalThe value representing pixels in the tile that don't contain an elevation value.
signal AbortSignaloptionalAn 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 namedAbortError
. See also AbortController.ReturnsType Description Promise<ElevationTileData> Resolves to an instance of ElevationTileData.
-
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.
ParametersReturns
-
hasEventListener
InheritedMethodhasEventListener(type){Boolean}
Inherited from Layer -
Indicates whether there is an event listener on the instance that matches the provided event name.
Parametertype StringThe name of the event.
ReturnsType Description Boolean Returns true if the class supports the input event.
-
hasHandles
InheritedMethodhasHandles(groupKey){Boolean}
Inherited from AccessorSince: ArcGIS Maps SDK for JavaScript 4.25Accessor since 4.0, hasHandles added at 4.25. -
Returns true if a named group of handles exist.
ParametergroupKey *optionalA group key.
ReturnsType 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
InheritedMethodisFulfilled(){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.ReturnsType Description Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).
-
isRejected
InheritedMethodisRejected(){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.ReturnsType Description Boolean Indicates whether creating an instance of the class has been rejected.
-
isResolved
InheritedMethodisResolved(){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.ReturnsType Description Boolean Indicates whether creating an instance of the class has been resolved.
-
load
InheritedMethodload(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 aLoadable
instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad can abort it.Parametersignal AbortSignaloptionalSignal 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
-
on
InheritedMethodon(type, listener){Object}
Inherited from Layer -
Registers an event handler on the instance. Call this method to hook an event with a listener.
ParametersReturnsType 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. Exampleview.on("click", function(event){ // event is the event handle returned after the event fires. console.log(event.mapPoint); });
-
queryElevation
queryElevation(geometry, options){Promise<ElevationQueryResult>}
Since: ArcGIS Maps SDK for JavaScript 4.12BaseElevationLayer 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 eitherfinest-contiguous
or a fixed{number}
resolution.ParametersSpecificationgeometry Point|Multipoint|PolylineThe geometry to use for sampling elevation data.
options ObjectoptionalAdditional query options. See the table below.
Specificationoptional Default Value: autoControls 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.demResolution Description 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 BooleanoptionalDefault Value: falseIndicates whether to return additional sample information for each coordinate.
noDataValue NumberoptionalDefault Value: 0The value to use when there is no data available.
ReturnsType Description Promise<ElevationQueryResult> Resolves to an object with the sampled geometry, resolution information, and no data value. - See also
-
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25Accessor since 4.0, removeHandles added at 4.25. -
Removes a group of handles owned by the object.
ParametergroupKey *optionalA group key or an array or collection of group keys to remove.
Exampleobj.removeHandles(); // removes handles from default group obj.removeHandles("handle-group"); obj.removeHandles("other-handle-group");
-
when
InheritedMethodwhen(callback, errback){Promise}
Inherited from LayerSince: ArcGIS Maps SDK for JavaScript 4.6Layer 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: acallback
function and anerrback
function. Thecallback
executes when the instance of the class loads. Theerrback
executes if the instance of the class fails to load.ParametersReturnsType 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 });
Type Definitions
-
Describes elevation contained in the pixels that comprise an elevation tile.
- Properties
-
The elevation values of each pixel in the tile.
width NumberThe width of the tile in pixels.
height NumberThe height of the tile in pixels.
maxZError NumberThe maximum allowed error of the Z-value for each value in meters.
noDataValue NumberIndicating the pixel values where no elevation data is present.
Event Overview
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
-
Inherited from Layer
-
Fires after the layer's LayerView is created and rendered in a view.
- Properties
- 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; });
-
Inherited from Layer
-
Fires when an error emits during the creation of a LayerView after a layer has been added to the map.
- Properties
- 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); });