This sample demonstrates how to create a custom ElevationLayer by creating a subclass of BaseElevationLayer. In some cases, you may want to exaggerate elevation in a SceneView to make it more pronounced at smaller scales.
Since this sample exaggerates existing elevation values, we require ElevationLayer and load the default ArcGIS TopoBathy3D service as a dependency of the custom layer. This is done inside the load() method because it is a loadable resource.
We'll also create an exaggeration property to specify the factor by which we'll exaggerate the elevation.
Use dark colors for code blocksCopy
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
const ExaggeratedElevationLayer = BaseElevationLayer.createSubclass({
properties: {
// exaggerates the actual elevations by 70xexaggeration: 70 },
load: function() {
this._elevation = new ElevationLayer({
url: "//elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/TopoBathy3D/ImageServer" });
// wait for the elevation layer to load before resolving load()this.addResolvingPromise(
this._elevation.load().then(() => {
// get tileInfo, spatialReference and fullExtent from the elevation service// this is required for elevation services with a custom spatialReferencethis.tileInfo = this._elevation.tileInfo;
this.spatialReference = this._elevation.spatialReference;
this.fullExtent = this._elevation.fullExtent;
})
);
returnthis;
}
});
Then we must manipulate the fetchTile() method of ExaggeratedElevationLayer so that it returns the proper values for each pixel. We can fetch the actual elevation values using ElevationLayer.fetchTile(), multiply them by the exaggeration value, and return them to fetchTile since the data object specification for fetchTile() in ElevationLayer is the same as it is for BaseElevationLayer. The final code for the custom elevation layer should look like the following.
Use dark colors for code blocksCopy
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
const ExaggeratedElevationLayer = BaseElevationLayer.createSubclass({
properties: {
// exaggerates the actual elevations by 70xexaggeration: 70 },
load: function() {
this._elevation = new ElevationLayer({
url: "//elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/TopoBathy3D/ImageServer" });
// wait for the elevation layer to load before resolving load()this.addResolvingPromise(
this._elevation.load().then(() => {
// get tileInfo, spatialReference and fullExtent from the elevation service// this is required for elevation services with a custom spatialReferencethis.tileInfo = this._elevation.tileInfo;
this.spatialReference = this._elevation.spatialReference;
this.fullExtent = this._elevation.fullExtent;
})
);
returnthis;
},
// Fetches the tile(s) visible in the viewfetchTile: function(level, row, col, options) {
returnthis._elevation.fetchTile(level, row, col, options).then(
function(data) {
const exaggeration = this.exaggeration;
for (let i = 0; i < data.values.length; i++) {
data.values[i] = 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.
For this sample we use the virtualLighting, which makes sure that the scene is always nicely lit and there are no parts of the globe in shadow. The position of the light follows the camera and is set behind the camera with a small offset to the left side.
Use dark colors for code blocksCopy
1
2
3
view.environment.lighting = {
type: "virtual"// autocasts as new VirtualLighting()}
