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OpenLayers 2 is an open source, web browser-based mapping library written in JavaScript. OpenLayers maps can also be viewed on mobile devices since no plugins are required to use it.

Requirements

• The OpenLayers mapping library included in your HTML file
• The map itself and all other layers must share the same projection (e.g., "geographic" EPSG:4326) since multiple projections are not supported in a concurrent fashion by OpenLayers.
• A reasonably modern web browser with JavaScript enabled.

Sample Clients

• The EOSDIS Worldview tool is based on OpenLayers and uses code similar to the above snippets.
• See here for simple examples: Geographic, Web Mercator, Arctic, and Antarctic or clone them on GitHub.

Usage (Geographic)

The following code snippets provide information for creating a basic OpenLayers-based GIBS client for imagery in the Geographic (EPSG:4326) projection.  See the info provided in the GIBS layer configuration information for details on configuring each layer. For this example, we will be using an imagery layer with a 250m resolution.

First create a map object with a geographic (i.e., lat-lon) projection.  Note that the numZoomLevels attribute has a value of 9, based on the table above.

map = new OpenLayers.Map({
    div: "map",
    projection: "EPSG:4326",
    numZoomLevels: 9,
    zoom: 2
});

Next, define service- and product-specific constants related to the map projection, resolution, and service endpoint (see here for more info):

var GIBS_WMTS_GEO_ENDPOINT = "http://gibs.earthdata.nasa.gov/wmts/epsg4326/best/wmts.cgi";
var TILEMATRIXSET_GEO_250m = "EPSG4326_250m";
var TILEMATRIXSET_GEO_2km  = "EPSG4326_2km";

Now create base and overlay layers for two products (more info on available products can be found here).  No style value is required for GIBS image accesses.  The isBaseLayer element should be set accordingly as to whether this is a base (true) or overlay (false) layer.  All base layers have a format of image/jpeg and all overlay layers have a format of image/png.

The maxResolution attribute has a value of 0.5625, based on the layer configuration information.  The serverResolution element is a listing of resolutions that are provided by the GIBS server (more info here).  The resolutions element is a listing of resolutions that should be provided to the end user (more info here).  If additional resolutions are included in the resolutions element that are not in the serverResolutions element, then OpenLayers will perform client-side "overzooming."

// Create base layers
var layerModisTerraTrueColor = new OpenLayers.Layer.WMTS({
	name: "Terra / MODIS Corrected Reflectance (True Color), 2012-06-08",
	url: GIBS_WMTS_GEO_ENDPOINT,
	layer: "MODIS_Terra_CorrectedReflectance_TrueColor",
	matrixSet: TILEMATRIXSET_GEO_250m,
	format: "image/jpeg",
	style: "",
	transitionEffect: "resize",
	projection: "EPSG:4326",
	numZoomLevels: 9,
	maxResolution: 0.5625,
    resolutions: [0.5625, 0.28125, 0.140625, 0.0703125, 0.03515625, 0.017578125, 0.0087890625, 0.00439453125, 0.002197265625], 
 serverResolutions: [0.5625, 0.28125, 0.140625, 0.0703125, 0.03515625, 0.017578125, 0.0087890625, 0.00439453125, 0.002197265625],
	'tileSize': new OpenLayers.Size(512, 512),
	isBaseLayer: true
});

// Create overlays
var layerModisAerosolOpticalDepth = new OpenLayers.Layer.WMTS({
	name: "Terra / MODIS Aerosol Optical Depth, 2012-06-08",
	url: GIBS_WMTS_GEO_ENDPOINT,
	layer: "MODIS_Terra_Aerosol",
	matrixSet: TILEMATRIXSET_GEO_2km,
	format: "image/png",
	style: "",
	transitionEffect: "resize",
	projection: "EPSG:4326",
	numZoomLevels: 9,
	maxResolution: 0.5625,
    resolutions: [0.5625, 0.28125, 0.140625, 0.0703125, 0.03515625, 0.017578125, 0.0087890625, 0.00439453125, 0.002197265625],
    serverResolutions: [0.5625, 0.28125, 0.140625, 0.0703125, 0.03515625, 0.017578125],
	'tileSize': new OpenLayers.Size(512, 512),
	isBaseLayer: false,
	visibility: false
});

// The "time" parameter isn't being included in tile requests to the server
// in the current version of OpenLayers (2.12);  need to use this hack
// to force the inclusion of the time parameter.
//
// If the time parameter is omitted, the current (UTC) day is retrieved
// from the server
layerModisTerraTrueColor.mergeNewParams({time:"2012-06-08"});
layerModisAerosolOpticalDepth.mergeNewParams({time:"2012-06-08"});

Finally, add the layers to the map, add a layer switcher, and set the view extent:

// Add layers to the map
map.addLayers([layerModisTerraTrueColor, layerModisTerra721,
	layerModisAerosolOpticalDepth]);
	
// Add layer switcher control
map.addControl(new OpenLayers.Control.LayerSwitcher());

// Set global view
var extent = "-146.0, -94.0, 146.0, 94.0";
var OLExtent = new OpenLayers.Bounds.fromString(extent, false).transform(
		new OpenLayers.Projection("EPSG:4326"),
		map.getProjectionObject());
map.zoomToExtent(OLExtent, true);

Usage (Polar Stereographic)

To use GIBS imagery in an Arctic Polar Stereographic (EPSG:3413) or Antarctic Polar Stereographic (EPSG:3031) projection, follow the same instructions as geographic but change the TileMatrixSets, number of zoom levels, and resolution parameters to match the polar projections as listed in the layer configuration info.  Please also note that only a subset of layers are available in Arctic and Antarctic compared to geographic.

Note that static variables are shown below for both the Arctic and Antarctic projections, but only Arctic layers are created.

var GIBS_WMTS_ARCTIC_ENDPOINT    = "http://gibs.earthdata.nasa.gov/wmts/epsg3413/best/wmts.cgi";
var GIBS_WMTS_ANTARCTIC_ENDPOINT = "http://gibs.earthdata.nasa.gov/wmts/epsg3031/best/wmts.cgi";
 
var TILEMATRIXSET_ARCTIC_250m = "EPSG3413_250m";
var TILEMATRIXSET_ARCTIC_500m = "EPSG3413_500m";

// The following are true for both Arctic and Antarctic
var maxPolarExtent = [-4194304, -4194304, 4194304, 4194304];
 
// Create base layers
var layerModisTerraTrueColor = new OpenLayers.Layer.WMTS({
	name: "Terra / MODIS Corrected Reflectance (True Color), 2012-06-08",
	url: GIBS_WMTS_ARCTIC_ENDPOINT,
	layer: "MODIS_Terra_CorrectedReflectance_TrueColor",
	matrixSet: TILEMATRIXSET_ARCTIC_250m,
	format: "image/jpeg",
	style: "",
	transitionEffect: "resize",
	projection: "EPSG:3413",
	numZoomLevels: 6,
	maxResolution: 8192.0,
    resolutions: [8192.0, 4096.0, 2048.0, 1024.0, 512.0, 256.0],
    serverResolutions: [8192.0, 4096.0, 2048.0, 1024.0, 512.0, 256.0],
	'tileSize': new OpenLayers.Size(512, 512),
	isBaseLayer: true
});

// Create overlays
var layerModisSnowCover = new OpenLayers.Layer.WMTS({
	name: "Terra / MODIS Snow Cover, 2012-06-08",
	url: GIBS_WMTS_ARCTIC_ENDPOINT,
	layer: "MODIS_Terra_Snow_Cover",
	matrixSet: TILEMATRIXSET_ARCTIC_500m,
	format: "image/png",
	style: "",
	transitionEffect: "resize",
	projection: "EPSG:3413",
	numZoomLevels: 6,
	maxResolution: 8192.0,
    resolutions: [8192.0, 4096.0, 2048.0, 1024.0, 512.0, 256.0],
    serverResolutions: [8192.0, 4096.0, 2048.0, 1024.0, 512.0],
	'tileSize': new OpenLayers.Size(512, 512),
	isBaseLayer: false,
	visibility: false
});

// The "time" parameter isn't being included in tile requests to the server
// in the current version of OpenLayers (2.12);  need to use this hack
// to force the inclusion of the time parameter.
//
// If the time parameter is omitted, the current (UTC) day is retrieved
// from the server
layerModisTerraTrueColor.mergeNewParams({time:"2012-06-08"});
layerModisSnowCover.mergeNewParams({time:"2012-06-08"});

The Flash/Flex client library is a native Flash client written in ActionScript. It can be embedded into Flash applications on web pages as well as an embedded application that utilizes the Adobe Air framework. It is built upon ArcGIS's Flex API libraries to load tiles and present images with a custom TWMS data loader.

The library comes with a sample HTML page that presents a simple Flash client which can load layers from arbitrary TWMS servers and allow users to select time-values.

Requirements

• Adobe Flash 10+
• ArcGIS Flex API Library 2.3.1+ (http://resources.arcgis.com/en/communities/flex-api/index.html)

Usage

To use the library, include the pre-compiled Flash library and use the following code snippet in the .mxml file.

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
			   xmlns:s="library://ns.adobe.com/flex/spark"
			   xmlns:mx="library://ns.adobe.com/flex/mx"
			   xmlns:esri="http://www.esri.com/2008/ags"
			   xmlns:layers="gov.nasa.jpl.common.gui.map.layers.*"
	<esri:Map id="map" logoVisible="false" scaleBarVisible="false">
	<layers:TiledWMSLayer url="http://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi" visibleLayer="MODIS TERRA tileset"/>
</esri:Map>
</s:Application>

Screenshots

Additional Documentation

The Flex API for ArcGIS can be obtained here.

Code Snippets

Adding a map layer (Provided by ArcGIS's API)

var tiledWMSLayer:TiledWMSLayer = new TiledWMSLayer();
tiledWMSLayer.url = <url>;
tiledWMSLayer.visibleLayer = String(<map name>);
tiledWMSLayer.dateString = <date>;
map.addLayer(tiledWMSLayer);

Sample Clients

World Wind is a multi-platform virtual globe developed by NASA that runs in Java. It can load GIBS data through either the KML interface or the TWMS interface.

Requirements

• NASA World Wind 1.3+ or the online JNLP demos
• Java 1.6+

Usage (KML)

To run the World Wind client with GIBS KML capabilities, load the "KML Viewer" demo application from either the standalone client or the online demo. To load a specific layer, select File | Open URL... and enter a URL for the layer in this format: http://<url to kmlgen.cgi>?layers=<layername>&time=<time> for example,  http://gibs.earthdata.nasa.gov/twms/epsg4326/best/kmlgen.cgi?layers=MODIS_Terra_CorrectedReflectance_TrueColor&time=2012-06-21

To enable time adjustment on a particular layer, use the following URL parameter: time=R10/<date>/P1D for example, http://gibs.earthdata.nasa.gov/twms/epsg4326/best/kmlgen.cgi?layers=MODIS_Terra_CorrectedReflectance_TrueColor&time=R10/2012-05-26/P1D

Additional documentation is available here.

Limitations: The name of the layer has to be known prior to entering the URL. The list of available layers can be found here.

Usage (TWMS)

To run the World Wind client with TWMS capabilities, load the WMS Layer Manager demo application from either the standalone client or the online demo. In the layers menu, add the TWMS endpoint. This will load the list of layers available from TWMS and selecting a layer will allow it to be shown on the globe.

Limitations: World Wind will continue to zoom and try to load images even if they're beyond the depth of the highest resolution tile. When this happens, the images will go blank. In addition, this interface does not allow the selection of variables such as time.

Screenshots

The iOS client library is a native library written in Objective-C and can be incorporated into any iOS app for the iPod Touch, iPhone, and iPad. It is built upon ArcGIS's iOS client libraries, which provides a MapView and asynchronous tile loading, coupled with a custom TWMS data loader.

The library comes with a sample client to display TWMS maps and includes basic manipulations such as presenting data from arbitrary TWMS server, selecting a time-value, and map layer reordering.

Requirements

• iOS 5.0+
• ArcGIS iOS Client Library 2.2.1+ (Download here)

Usage

To use the library, create an AGSMapView object, either programmatically or linked from Interface Builder, and use the following code snippet as an example.

TWMSTiledWebMapService *earthTwms = [[TWMSTiledWebMapService alloc] initWithUrl:[NSURL URLWithString:@"http://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi?request=GetTileService"]];
TWMSTiledMap *aquaMap = [[earthTwms tiledMaps] valueForKey:@"MODIS AQUA tileset"];
TWMSTiledMapLayer *aquaMapLayer = [[TWMSTiledMapLayer alloc] initWithTiledMap:aquaMap];
[agsMapView addMapLayer:aquaMapLayer withName:[aquaMap name]];

Screenshots

Additional Documentation

The ArcGIS iOS documentation can be obtained here.

The standard iOS documentation can be viewed here.

The iOS library defines 3 classes that are used to load TWMS data:

TWMSTiledWebMapService: Instantiated for each TWMS endpoint.

TWMSTiledMap: Represents an individual map layer in the TWMS.

TWMSTiledMapLayer: A subclass of ArcGIS's map layer to show TWMS data.

TWMSTiledWebMapService

Properties

name: The name of the TWMS as defined in the GetTiledService request.

title: The title of the TWMS as defined in the GetTiledService request.

abstract: The abstract of the TWMS as defined in the GetTiledService request.

tiledMaps: A dictionary where the keys are the name of each map layer and values are the TWMSTiledMap instances.

Methods

(id)initWithUrl:(NSURL*)url: Loads the TWMS data given by the url to instantiate this class.

(NSArray*)listAllTiledMapsByName: Returns a sorted list of map layer names.

(void)setTiledMapKeyValue:(NSString*)value forTiledMapKey:(NSString*)key: Assigns variable keys for all TiledMaps in the TWMS server.

(NSDictionary*)tiledMapKeyValues: Returns a dictionary of all the keys used in all TiledMaps and the value its currently set to.

TWMSTiledMap  Properties

name: The name of the layer as defined in the GetTiledService request.

title: The title of the layer as defined in the GetTiledService request.

uuid: A randomly generated unique ID for the layer.

Code Snippets

Create a new TWMSTiledWebMapService using a URL

TWMSTiledWebMapService *earthTwms = [[TWMSTiledWebMapService alloc] initWithUrl:[NSURL URLWithString:@"http://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi?request=GetTileService"]];

List all map layers in a TWMS server

NSArray *tiledMapNames = [earthTwms listAllTiledMapsByName];
for(NSString *tiledMapName in tiledMapNames) {
	NSLog(@"%@", tiledMapName);
}

Update variables for all TWMS endpoints

[earthTwms setTiledMapKeyValue:@"2012-07-12" forTiledMapKey:@"${time}"];

Add, reorder, and remove map layers (Provided by ArcGIS's MapView class)

AGSMapView *mapView = <the map view>;
TWMSTiledMap *tiledMap = <obtained from TWMSTiledWebMapService>;
TWMSTiledMapLayer *tiledMapLayer = [[TWMSTiledMapLayer alloc] initWithTiledMap:tiledMap];

[mapView addLayer:tiledMapLayer withName:[tiledMap uuid]];
[mapView insertMapLayer:tiledMapLayer withName:[tiledMap uuid] atIndex:<index>];
[mapView removeLayerWithName:[tiledMap uuid]];

       Set map layer transparency (Provided by iOS UIView's transparency settings) 
    

UIView *view = [[[mapView mapLayerViews] objectForKey:[tiledMap uuid]];
[view setAlpha:<transparency value>];