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ArcGisImageServerTerrainProvider.js
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ArcGisImageServerTerrainProvider.js
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/*global define*/
define([
'../ThirdParty/when',
'./Credit',
'./defaultValue',
'./defined',
'./defineProperties',
'./DeveloperError',
'./Ellipsoid',
'./Event',
'./GeographicTilingScheme',
'./getImagePixels',
'./HeightmapTerrainData',
'./loadImage',
'./Math',
'./TerrainProvider',
'./throttleRequestByServer'
], function(
when,
Credit,
defaultValue,
defined,
defineProperties,
DeveloperError,
Ellipsoid,
Event,
GeographicTilingScheme,
getImagePixels,
HeightmapTerrainData,
loadImage,
CesiumMath,
TerrainProvider,
throttleRequestByServer) {
'use strict';
/**
* A {@link TerrainProvider} that produces terrain geometry by tessellating height maps
* retrieved from an ArcGIS ImageServer.
*
* @alias ArcGisImageServerTerrainProvider
* @constructor
*
* @param {Object} options Object with the following properties:
* @param {String} options.url The URL of the ArcGIS ImageServer service.
* @param {String} [options.token] The authorization token to use to connect to the service.
* @param {Object} [options.proxy] A proxy to use for requests. This object is expected to have a getURL function which returns the proxied URL, if needed.
* @param {TilingScheme} [options.tilingScheme] The tiling scheme specifying how the terrain
* is broken into tiles. If this parameter is not provided, a {@link GeographicTilingScheme}
* is used.
* @param {Ellipsoid} [options.ellipsoid] The ellipsoid. If the tilingScheme is specified,
* this parameter is ignored and the tiling scheme's ellipsoid is used instead.
* If neither parameter is specified, the WGS84 ellipsoid is used.
* @param {Credit|String} [options.credit] The credit, which will is displayed on the canvas.
*
*
* @example
* var terrainProvider = new Cesium.ArcGisImageServerTerrainProvider({
* url : 'https://elevation.arcgisonline.com/ArcGIS/rest/services/WorldElevation/DTMEllipsoidal/ImageServer',
* token : 'KED1aF_I4UzXOHy3BnhwyBHU4l5oY6rO6walkmHoYqGp4XyIWUd5YZUC1ZrLAzvV40pR6gBXQayh0eFA8m6vPg..',
* proxy : new Cesium.DefaultProxy('/terrain/')
* });
* viewer.terrainProvider = terrainProvider;
*
* @see TerrainProvider
*/
function ArcGisImageServerTerrainProvider(options) {
//>>includeStart('debug', pragmas.debug);
if (!defined(options) || !defined(options.url)) {
throw new DeveloperError('options.url is required.');
}
//>>includeEnd('debug');
this._url = options.url;
this._token = options.token;
this._tilingScheme = options.tilingScheme;
if (!defined(this._tilingScheme)) {
this._tilingScheme = new GeographicTilingScheme({
ellipsoid : defaultValue(options.ellipsoid, Ellipsoid.WGS84)
});
}
this._heightmapWidth = 65;
this._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(this._tilingScheme.ellipsoid, this._heightmapWidth, this._tilingScheme.getNumberOfXTilesAtLevel(0));
this._proxy = options.proxy;
this._terrainDataStructure = {
heightScale : 1.0 / 1000.0,
heightOffset : -1000.0,
elementsPerHeight : 3,
stride : 4,
elementMultiplier : 256.0,
isBigEndian : true,
lowestEncodedHeight : 0,
highestEncodedHeight : 256 * 256 * 256 - 1
};
this._errorEvent = new Event();
var credit = options.credit;
if (typeof credit === 'string') {
credit = new Credit(credit);
}
this._credit = credit;
this._readyPromise = when.resolve(true);
}
defineProperties(ArcGisImageServerTerrainProvider.prototype, {
/**
* Gets an event that is raised when the terrain provider encounters an asynchronous error. By subscribing
* to the event, you will be notified of the error and can potentially recover from it. Event listeners
* are passed an instance of {@link TileProviderError}.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Event}
*/
errorEvent : {
get : function() {
return this._errorEvent;
}
},
/**
* Gets the credit to display when this terrain provider is active. Typically this is used to credit
* the source of the terrain. This function should not be called before {@link ArcGisImageServerTerrainProvider#ready} returns true.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Credit}
*/
credit : {
get : function() {
return this._credit;
}
},
/**
* Gets the tiling scheme used by this provider. This function should
* not be called before {@link ArcGisImageServerTerrainProvider#ready} returns true.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {GeographicTilingScheme}
*/
tilingScheme : {
get : function() {
return this._tilingScheme;
}
},
/**
* Gets a value indicating whether or not the provider is ready for use.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Boolean}
*/
ready : {
get : function() {
return true;
}
},
/**
* Gets a promise that resolves to true when the provider is ready for use.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Promise.<Boolean>}
* @readonly
*/
readyPromise : {
get : function() {
return this._readyPromise;
}
},
/**
* Gets a value indicating whether or not the provider includes a water mask. The water mask
* indicates which areas of the globe are water rather than land, so they can be rendered
* as a reflective surface with animated waves. This function should not be
* called before {@link ArcGisImageServerTerrainProvider#ready} returns true.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Boolean}
*/
hasWaterMask : {
get : function() {
return false;
}
},
/**
* Gets a value indicating whether or not the requested tiles include vertex normals.
* This function should not be called before {@link ArcGisImageServerTerrainProvider#ready} returns true.
* @memberof ArcGisImageServerTerrainProvider.prototype
* @type {Boolean}
*/
hasVertexNormals : {
get : function() {
return false;
}
}
});
/**
* Requests the geometry for a given tile. This function should not be called before
* {@link ArcGisImageServerTerrainProvider#ready} returns true. The result includes terrain
* data and indicates that all child tiles are available.
*
* @param {Number} x The X coordinate of the tile for which to request geometry.
* @param {Number} y The Y coordinate of the tile for which to request geometry.
* @param {Number} level The level of the tile for which to request geometry.
* @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry. If this method
* returns undefined instead of a promise, it is an indication that too many requests are already
* pending and the request will be retried later.
*/
ArcGisImageServerTerrainProvider.prototype.requestTileGeometry = function(x, y, level) {
var rectangle = this._tilingScheme.tileXYToRectangle(x, y, level);
// Each pixel in the heightmap represents the height at the center of that
// pixel. So expand the rectangle by half a sample spacing in each direction
// so that the first height is on the edge of the rectangle we need rather than
// half a sample spacing into the rectangle.
var xSpacing = (rectangle.east - rectangle.west) / (this._heightmapWidth - 1);
var ySpacing = (rectangle.north - rectangle.south) / (this._heightmapWidth - 1);
rectangle.west -= xSpacing * 0.5;
rectangle.east += xSpacing * 0.5;
rectangle.south -= ySpacing * 0.5;
rectangle.north += ySpacing * 0.5;
var bbox = CesiumMath.toDegrees(rectangle.west) + '%2C' + CesiumMath.toDegrees(rectangle.south) + '%2C' + CesiumMath.toDegrees(rectangle.east) + '%2C' + CesiumMath.toDegrees(rectangle.north);
var url = this._url + '/exportImage?interpolation=RSP_BilinearInterpolation&format=tiff&f=image&size=' + this._heightmapWidth + '%2C' + this._heightmapWidth + '&bboxSR=4326&imageSR=4326&bbox=' + bbox;
if (this._token) {
url += '&token=' + this._token;
}
var proxy = this._proxy;
if (defined(proxy)) {
url = proxy.getURL(url);
}
var promise = throttleRequestByServer(url, loadImage);
if (!defined(promise)) {
return undefined;
}
var that = this;
return when(promise, function(image) {
return new HeightmapTerrainData({
buffer : getImagePixels(image),
width : that._heightmapWidth,
height : that._heightmapWidth,
childTileMask : 15, // all children present
structure : that._terrainDataStructure
});
});
};
/**
* Gets the maximum geometric error allowed in a tile at a given level.
*
* @param {Number} level The tile level for which to get the maximum geometric error.
* @returns {Number} The maximum geometric error.
*/
ArcGisImageServerTerrainProvider.prototype.getLevelMaximumGeometricError = function(level) {
return this._levelZeroMaximumGeometricError / (1 << level);
};
/**
* Determines whether data for a tile is available to be loaded.
*
* @param {Number} x The X coordinate of the tile for which to request geometry.
* @param {Number} y The Y coordinate of the tile for which to request geometry.
* @param {Number} level The level of the tile for which to request geometry.
* @returns {Boolean} Undefined if not supported, otherwise true or false.
*/
ArcGisImageServerTerrainProvider.prototype.getTileDataAvailable = function(x, y, level) {
return undefined;
};
return ArcGisImageServerTerrainProvider;
});