What are the World Elevation services?

The World Elevation services provide online access to global collections of multiresolution and multisource elevation data. This collection includes data with resolutions ranging from 230 meters to 3.1 meters. The services provide a single endpoint for desktop and web applications to access elevation values, derived products, and geoprocessing tools.

You can use the services in your desktop and web applications as follows:

  • As information layers, such as a hillshade or aspect
  • To orthorectify imagery
  • As a data source for your analysis models or other geoprocessing tasks
  • To run server-side geoprocessing tools
  • 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 raw elevation data or derived products (for example, hillshade) without needing to store, compile, and process the source data on your local machine. They are available on ArcGIS Online. See the Elevation Layers group for access to the entire collection.

The image services provided for visualization can be used as base images in your desktop applications, such as ArcMap, or in web applications to provide context for other layers. The recommended services include the following:

  • Elevation Tinted Hillshade—A tinted hillshade surface created from the world digital terrain model (DTM).
  • Grayscale Hillshade—A grayscale hillshade created from the DTM.
  • Aspect Map—Aspect generated from the DTM. Rendered with color such that the orientation of the downward-sloping terrain is indicated by different colors, rotating from green to blue to red to yellow (clockwise from north).
  • Slope Map—Slope generated from the DTM. Rendered with color to represent flat to steep slope (grey to yellow to red).
Image services

The image services provided for analysis can be used by software applications as a data source for their own analysis or to store a local copy of an area of the elevation data to process other imagery, such as performing an orthorectification. The recommended services for analysis include the following:

  • Terrain—The DTM that defines the ground surface. Heights are orthometric and sea level = 0.
  • Aspect—Aspect generated from the DTM. Values represent the orientation of the downward-sloping terrain as 0 to 360 degrees.
  • Slope Degrees—Slope generated from the DTM. Values represent the angle of the downward-sloping terrain from 0 to 90 degrees.
  • Slope Percent—Slope generated from the DTM. Values represent the angle of the downward-sloping terrain as a percentage, from 0 to 1,000 percent (for example, 45 degree slope = 100 percent, representing the vertical rise divided by the horizontal distance).

The server-side geoprocessing tools allow the user to control the area of interest and tool parameters, perform all processing on the server, and then transmit only the output to the client software. Since the elevation data is a large data volume, transmitting only the results from server to client (as a feature class or array of numeric values) is much faster than downloading the raw data and performing local analysis. The geoprocessing tools include the following:

  • Viewshed
  • Profile (tabular values)
  • Summarize Elevation (area of interest statistics)
  • Watershed
  • Trace Downstream

To learn more about the elevation tools, see Overview of the Elevation Analysis services.

Applications and samples

There are several example applications available on ArcGIS Online to demonstrate how you can work with the World Elevation image services. One is the World Elevation Reviewer, a sample web application created using Microsoft Silverlight for exploring the World Elevation services.

Sources

The source elevation data is composed of the best available elevation data and samples from public domain sources. The data providers include the following:

  • www.usgs.gov
  • www.cgiar-csi.org
  • www.nasa.gov

The data sources include National Elevation Dataset (NED), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data (GMTED). They range in resolution from 230 meters to 3.1 meters. Not all datasets cover the entire earth’s surface.

If you have data you would like to contribute, contact worldelevation@esri.com.

How to use these services

To learn more about the World Elevation services and how to use them, see the following: