There are several supported map libraries available to take advantage of NASA's Global Imagery Browse Services (GIBS) via OGC Web Map Tile Service (WMTS), Tiled Web Map Service (TWMS), and KML files. Listed below is a set of map libraries, code snippets, working examples, and screen captures designed to help in building your own user interface to explore NASA's Earth imagery. Alternatively, these guidelines can also help to integrate that imagery into your existing client or to build scripts to retrieve imagery from GIBS. Geographic Information System (GIS) users: go here for instructions.
Code Available in GitHub
In addition to the snippets below, fully-working code examples are available for OpenLayers and Leaflet in the GIBS GitHub project area.
See the Live Examples (including Geographic, Web Mercator, Arctic, and Antarctic, notes on using OpenLayer 3 with GIBS, and clone the GIBS Web Examples from GitHub to tinker with the code. The EOSDIS Worldview tool (source) is based on OpenLayers 3, too.
See the Live Examples (including Geographic, Web Mercator, Arctic, and Antarctic), notes on using Leaflet with GIBS, and clone the GIBS Web Examples from GitHub to tinker with the code. For details on how to configure specific layers available from GIBS, follow the relevant instructions included in the GIBS Layer Configuration Information.
Google Earth does not have a convenient method of layering maps on top of each other. One can achieve the effect by changing the elevation that the map layers are displayed at, although that sometimes can introduct unwanted artifacts on the display.
GIBS data displayed in the Google Earth Plugin (As used in PO.DAAC's State of the Ocean when "MODIS True Color" layers are selected)
Desktop Application Libraries
NASA World Wind 1.3+ or the online JNLP demos
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: https://<url to kmlgen.cgi>?layers=<layername>&time=<time> for example, https://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, https://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.
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.
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Mobile App Libraries
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.
ArcGIS iOS Client Library 2.2.1+ (Download here)
To use the library, create an AGSMapView object, either programmatically or linked from Interface Builder, and use the following code snippet as an example.
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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.
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.
(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.
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.
Create a new TWMSTiledWebMapService using a URL
List all map layers in a TWMS server
Update variables for all TWMS endpoints
Add, reorder, and remove map layers (Provided by ArcGIS's MapView class)
Set map layer transparency (Provided by iOS UIView's transparency settings)
The Geospatial Data Abstraction Library (GDAL) WMS driver supports several internal 'minidrivers' that allow access to different web mapping services. Each of these services may support a different set of options in the Service block. Documentation for these minidrivers can be found here on the GDAL website. Two of these minidrivers in particular can be used by users to download GIBS imagery programmatically. They are the Tile Map Specification (TMS) and the OnEarth Tiled WMS (TiledWMS) minidrivers. Examples for both of these minidrivers will be included below.
GDAL version 1.9.1 or greater with cURL support enabled. To check if cURL is enabled for GDAL, type "gdalinfo --format WMS". If cURL is enabled you will see information about the WMS format, if not, you will get an error message and you will need to reconfigure GDAL to support cURL.
Sample Execution #1 - "TMS" Driver Configuration File Input
Create a local service description XML file and invoke gdal_translate. In this example, GIBS_Aqua_MODIS_true.xml is used to generate a true color JPEG image from Aqua MODIS of a smoke plume from western fires over the central United States. The contents of GIBS_Aqua_MODIS_true.xml would be:
In very limited testing, our experience has been that better image quality is obtained by using the GeoTIFF output format from the GDAL WMS, then converting this to other formats, if desired, using a second gdal_translate command, or other programs such as ImageMagick convert.
Sample Execution #2 - "TMS" Driver Command Line Input
Invoke gdal_translate with the content of the local service description XML file embedded into the command. This approach is useful for automated scripting to download various layers, dates, etc. To generate the same image as above:
For both options, the information needed to create the local service description XML can be found in the large table on the GIBS Available Imagery Products page.
Items that may need to be changed include:
layer_name - use "Layer Name on Server" from Products page. Note that only one layer can be retrieved per gdal_translate call.
date - use the desired date in YYYY-MM-DD format
resolution - use the "Resolution" in the format ####m from the "Imagery Resolution" column on the GIBS Available Imagery Products page, or GoogleMapsCompatible_Level# resolution from table below
format - use jpg or png extension based on the "Format"
2) Bounding box - use -180.0, 90, 396.0, -198 for Geographic projection and -4194304, 4194304, 4194304, -4194304 for the Polar projections. This is the bounding box of the topmost tile, which matches the bounding box of the actual imagery for Polar but not for Geographic.
3) <TileLevel> - select from the table below based on "Resolution" and "Projection". Note that the TileLevel in the table below is the maximum for that resolution. You can specify a lower value of TileLevel to force GDAL to use coarser resolution input tiles. This can be used to speed up projection, for example during development and testing.
4) <TileCountX><TileCountY> - use 2, 1 for Geographic projection and 2, 2 for Polar projections
6) <Bands> - use 3 for .jpg (except use 1 for ASTER_GDEM_Greyscale_Shaded_Relief) and 4 for .png
Note that the values for <YOrigin>, <BlockSizeX>, and <BlockSizeY> are constant for all GIBS layers.
More information on GDAL_WMS can be found here (note the "TMS" section).
Sample Execution #3 - "TiledWMS" Driver Configuration File Input
The TiledWMS GDAL minidriver relies on a simplified set of XML configuration from the user, pulling all other information from the TWMS WMS_Tile_Service document at runtime. The following example requests the same image as was requested in Sample Execution #1, but you will notice how much simpler the XML configuration is. The primary difference is that requests through TWMS utilize a TiledGroupName value instead of the WMTS Identifier utilized by WMTS requests. In almost all cases the TiledGroupName can be generated by replacing all underscores in a WMTS layer's Identifier with spaces and appending " tileset". For example, a WMTS Layer Identifier of SMAP_L1_Passive_Faraday_Rotation_Aft" becomes the TWMS TiledGroupName "SMAP L1 Passive Faraday Rotation Aft tileset". Unfortunately there are a few exceptions, which include the sample layer used below.
Sample Execution #4 - "TiledWMS" Driver Command Line Input
This example invokes gdal_translate with the content of the TileWMS local service description XML file embedded as a command line argument. This approach is useful for automated scripting to download various layers, dates, etc. To generate the same image as above, run the following:
Configuration File Input w/ Transparent PNG
In this example, GIBS_OMI_AI.xml is used to generate a transparent PNG image from the OMI Aerosol Index over the same region as the first two examples. The "Layer Name on Server" and EPSG/resolution in <ServerURL>, the <TileLevel>, and the <BandsCount> have changed from the first examples. The contents of GIBS_OMI_AI.xml would be:
In this example, GIBS_Terra_MODIS_Arctic.xml is used to generate a true color JPEG image from Terra MODIS of a phytoplankton bloom in the Barents Sea. The "Layer Name on Server" and EPSG/resolution in <Serverurl>, the <DataWindow> elements, and the <Projection> have changed from the first examples. The contents of GIBS_Terra_MODIS_Arctic.xml would be:
GeoTIFF files created by GDAL using the default tags for the GIBS polar projections do not work correctly in some GIS programs. So we recommend specifying the output projection in PROJ4 format:
The projection string for the GIBS Antarctic projection is "+proj=stere +lat_0=-90 +lat_ts=-71 +lon_0=0 +k=1 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs". Here are the links for the Arctic or Antarctic PROJ4 definitions. Some other workarounds are:
2) Use JPEG format instead. This will create a .jpg.aux.xml file in addition to the .jpg file.
Polar Layer w/ Reprojection
In this example, GIBS_Aqua_MODIS_Arctic.xml is used to generate a true color JPEG image from Aqua MODIS of the Beaufort Sea reprojected to have 145W down. The "Layer Name on Server" and EPSG/resolution in <Serverurl>, the <DataWindow> elements, and the <Projection> have changed from the first examples. The contents of GIBS_Aqua_MODIS_Arctic.xml would be:
Reprojecting GIBS Geographic layer into Polar Stereographic
Only a subset of layers are available from GIBS in the polar projections. This is an example of how to project a geographic layer into a polar projection. The contents of GIBS_Terra_Cloud_Fraction.xml would be:
The "-wo SOURCE_EXTRA=100 -wo SAMPLE_GRID=YES" arguments are needed to ensure that the output region is completely filled. The "-wo SOURCE_EXTRA=100" caused GDAL to request tiles outside of input bounding region. Normally GDAL would halt when it receives these errors so the <ZeroBlockHttpCodes> includes the 400 error to allow GDAL to continue. Note that this command may take a long time to complete, especially at higher input and output resolutions.