World Elevation services

The World Elevation services provide simple, online access to global collections of multi-resolution, multi-source elevation data. This collection includes data with resolutions ranging from approximately 1 kilometer to less than 1 meter. The services provide a single endpoint for desktop and web applications to access elevation values and derived products.

You can use these services in your desktop and web applications:

• As information layers, such as a hillshade or aspect
• To orthorectify imagery
• As a data source in your analysis models or other geoprocessing tasks
• To obtain data locally

Image services

These image services support visualization and analysis, with different services optimized for different purposes. They provide access to the elevation data (raw data) or products (e.g. hillshade) you require, without having to store, compile, and process the source data on your local machine. They are are available on ArcGIS Online. You can access them individually or search for the World Elevation group to access the entire collection.

The image services that are provided for visualization can be used as base images in your Desktop applications, such as ArcMap, or web applications to support the other data. The recommended services include:

• World Elevation DTM Hillshade—A grayscale hillshaded created from the DTM.
• World Elevation DSM Hillshade—A grayscale hillshade created from the DSM.
• World DTM Elevation Tinted Hillshade— A tinted hillshade surface created from the World Digital Terrain Model.
• World Elevation Aspect Map—Aspect generated from the DTM. Rendered with color such that the orientation of the downward sloping terain is indicated by different colors, rotating from green to blue to red to yellow (clockwise from north).
• World Elevation Slope Map—Slope generated from the DTM. Rendered with color to represent flat to steep slope (green to red).
• World TopoBathy Hillshade—Hillshaded surface created from ground height topography and bathymetry measurements.
• World TopoBathy Elevation Tinted Hillshade—A tinted hillshade surface created from ground height topography and bathymetry measurements.

The image services that are provided for analysis can be used by applications that will either use the image service as a source for their own analysis, or to use the elevation data to process other imagery, such as performing an orthorectification. The recommended services for analysis include:

• World Digital Terrain Model (DTM)—A digital elevation model (DEM) that defines the ground surface. Heights are orthometric and sea level = 0.
• World Digital Surface Model (DSM)—A DEM that defines the first return surface elevation values (includes features, such as building tops, bridges, and tree canopies).
• World Elevation Aspect—Aspect generated from the DTM. Values represent the orientation of the downward sloping terrain in degrees (0 to 359), clockwise from north.
  
• World Elevation Slope—Slope generated from the DTM. Values represent the angle of the downward sloping terrain from 0 to 90 degrees. 
• World Elevation Surface Height—Surface heights based on subtracting the ground elevation from the highest available surface heights.
• World DTM Ellipsoidal— Digital terrain model (DTM) of ground surface heights representing ellipsoidal measurements calculated by adding the EGM2008 geoid model.

Applications

There are several example applications available on ArcGIS Online to demonstrate how you can work with the World Elevation image services, such as:

• World Elevation Reviewer—A sample web application created with Microsoft Silverlight for exploring the World Elevation services.
• Tour of the World's larger craters—An ArcGIS Explorer Online presentation using several of the World Elevation service to highlight the location of some craters on the Earth's surface.

Sources

The source elevation data is comprised of the best publically available elevation data and some samples from commercial vendors. The data providers include:

Sources	Data	Approximate Cell Size (m)
www.oregonmetro.gov	Portland Lidar DEM	0.9
www.intermap.com	Intermap DEM	4.6
www.usgs.gov	NED 2, 1, 1/3rd, 1/9th arc second DEM	62 - 3.1
www.usgs.gov www.cgiar-csi.org www.nasa.gov	SRTM DEM	93
www.usgs.gov	GMTED DEM	232
www.bodc.ac.uk	GEBCO bathymetry	928
earth-info.nga.mil	EGM2008	4938

If you want to contribute, contact worldelevation@esri.com. For more information...

Learn more about these image services