With the Elevation and ElevationSync geoprocessing services running on your Data Appliance, you can perform actual raster analysis and map and share the results with other people in your organization. By having these services running on a Data Appliance, you don't need to worry about finding authoritative base data. You can create results more quickly than if you had to acquire and maintain terabytes of data on local machines.
With Data Appliance 6.3 for ArcGIS, the elevation geoprocessing tool, Profile, is available. Additional analytical tools are being considered for subsequent releases. The first thing you need to do to access the functionality is activate the particular service, which is discussed in the next section. More specific details on the Profile tool are provided in the section after that.
About the elevation geoprocessing services
Once you've published the elevation geoprocessing services, you can only use the services in ArcGIS 10.3 or later.
For general information on using services, see Using geoprocessing services in ArcGIS for Desktop in the ArcGIS for Server help under Publish Services > Types of services > Geoprocessing services > Using geoprocessing services.
The elevation data used by the services is collated and curated by Esri and made available as a part of the Data Appliance installation. A key benefit is that the elevation data has already been preprocessed and optimized for fast performance. As new areas and better resolutions are made available, they will be included in future updates.
The elevation data comes from the U.S. Geological Survey (USGS), U.S. National Geospatial-Intelligence Agency (NGA), U.S. National Aeronautics and Space Administration (NASA), and other authoritative sources. While elevation data is available for the entire surface of the earth, there are higher resolutions available for particular geographic extents. The following table lists the available data resolutions, the area covered by each, and the primary sources. The data is actually furnished in a spherical coordinate system with units of arcseconds, but they are listed here by their metric approximations for convenience.
10 meters (1/3 arcsecond)
The continental United States.
USGS National Elevation Dataset.
30 meters (1 arcsecond)
1. The continental United States, Canada, and Mexico.
2. Africa, South America, most of Europe and continental Asia, the East Indies, New Zealand, and islands of the western Pacific between 60 degrees north and 56 degrees south.
1. USGS National Elevation Dataset.
2. The 1 arcsecond (approximately 30 meters) resolution Shuttle Radar Topography Mission (SRTM) dataset.
3. In Australia, the tool is available based on the 1 arcsecond (approximately 30 meters) resolution SRTM DEM-S dataset from Geoscience Australia.
90 meters (3 arcseconds)
The land surface of the world between 60 degrees north and 56 degrees south.
Shuttle Radar Topography Mission (SRTM).
1,000 meters (30 arcseconds)
The entire surface of the world.
General Bathymetric Chart of the Oceans (GEBCO).
Bathymetry data for the oceans is also included in the global elevation service, allowing you to derive profiles down to the sea floor over ocean areas.
Control the resolution
Which source data is used depends on the setting of the DEM Resolution parameter as well as the particular location of the line feature for which you are trying to create a profile.
The Profile tool allows you to create profiles of your choosing anywhere on the surface of the earth.
What is an elevation profile?
An elevation profile shows you the height (or depth) of a surface along the length of a linear feature. It is an effective way to visualize and understand the elevation and topography of the surface of the earth.
Using the Profile tool
To create a profile, the first thing you need to do is make a server connection to the ArcGIS server of your Data Appliance that is hosting the elevation geoprocessing services. Once that has been done, you are ready to start creating profiles. The following steps walk you through the process.
- In the Catalog window, after connecting to the server, expand the Elevation and ElevationSync server toolboxes.
Note that there are actually two Profile tools available. The first is for asynchronous applications and the second for synchronous ones. The differences are explained further below.
- Double-click a Profile tool to open the tool dialog box.
- Specify the line for which you want to create the profile. There are two ways you can do this, depending on how the Input Line Features parameter is set:
- Click the InputLineFeatures option to use the interactive drawing tool to draw your profile line directly on the map. Use a single-click to add a vertex and a double-click to finish.
- Click the browse button to browse to and select an existing line feature for which you want to create a profile.
- Set the other parameters as you prefer, and specify a value for the maximum sample distance parameter.
- Click OK to run the task.
The output is a polyline feature with elevation values extracted along the line you specified. The elevation values and distance values are stored as Z and M values in the resulting feature set. The following is an example of the attribute table for the polyline feature:
To learn how to display the output as a profile graph, see How to display the results for the steps.
The difference between the asynchronous and synchronous Profile tools
As noted above, there are two Profile tools available, one in the Elevation toolbox and the other in the ElevationSync toolbox. They both do essentially the same thing, but each has a slightly different intended use. The first one is an asynchronous task, designed for long-running tasks, such as batch processing a large number of profile lines at once from a single input feature class. The synchronous task (the one in the ElevationSync toolbox) is designed for interactive profile applications, which typically have fewer input lines and require a faster response. For example, if you are creating a profile web app that generates profile graphs on the fly, use the synchronous tool.
When used in ArcMap, there should be no noticeable difference between the asynchronous and synchronous Profile tools, with the exception that the asynchronous profile tool allows a maximum of 1,000 input line features at a time, whereas the synchronous profile tool allows a maximum of 100.
The following are the parameters for the tool:
Input Line Features
The line feature for the information necessary to create a profile.
Profile ID Field
A string or integer unique identifier to tie profiles to their corresponding input line features.
The approximate spatial resolution (cell size) of the source elevation data used for the calculation. The default is 90m.
The available values are FINEST | 10m | 30m | 90m | 1000m.
The resolution keyword is an approximation of the spatial resolution of the digital elevation model. While many elevation sources are distributed in units of arcseconds, the keyword is an approximation of those resolutions in meters for easier understanding. The Finest option indicates that the highest resolution DEM possible is to be used.
The maximum sampling distance along the line to sample elevation values.
Sample Distance Units
The units for the MaximumSampleDistance.
The available values are Meters | Kilometers | Feet | Yards | Miles.
- The output line features are in the same coordinate system as the input line features. The Z and M values of the vertices are in meters.
- The output field Length Meters holds the planimetric length of the profile line calculated as a geodesic distance and is the correct length regardless of the coordinate system of the data. This length will be different from the shape_length attribute due to the effects of map projection distortion.
- When the Sample Distance parameter is empty, or not supplied, a default sampling distance is calculated based on how many vertices are available on the input line feature. If the input line feature contains less than 50 vertices, the default sampling distance is the length of the input line feature divided by 49. If the input has 50 or more, but less than 200 vertices, the default sampling distance is the length of the input line feature divided by 199. If the number of vertices is from 200 to the maximum of 1,024, the input line feature will not be densified if the Sample Distance parameter is empty or not specified.
- The maximum number of input lines is 1,000 for the asynchronous profile task. For the synchronous profile task, the maximum number of input lines is 100. If additional input lines are provided, the service will return an error and will not execute.
- The maximum number of elevation values returned from the task is 2,000 for each input line. The task will return an error message and will not execute if a request results in more than this maximum number of elevation values. If this occurs, you should either specify a larger sampling distance, or input a line feature with fewer vertices, or both.
- The task will return an error message if the specified DEM resolution is not available at any of the input feature locations.
Displaying the results
A profile records the elevations along the length of a line across the surface. To model this correctly in three-dimensional space, a 3D polyline feature class that records M and Z values at each vertex is created as output from the Profile tool. The distance between each vertex and the origin is recorded in the M value, and the elevation of the vertex is recorded in the Z value.
The polyline feature class is only of limited use for visualizing the profile. However, once it has been created, you can generate an attribute table from it that gives details about the vertices of the profile line and the elevations at those locations. You can load the contents of this table into a graphical display package and create a profile graph from it, or you can create a graph directly within ArcMap.
Creating an attribute table of profile segments
Use the following procedure to convert the polyline feature class into an attribute table of line segments that comprise the profile:
- Use the Feature Vertices to Points geoprocessing tool to extract all the vertices from the line feature class to a point feature class.
- Use the Add XY Coordinates tool on this new feature class. This will append the X, Y, Z, and M values to the attribute table as Point_X, Point_Y, Point_Z and Point_M fields.
The attribute table will appear similar to the following:
Creating a graph in ArcMap
Once you have the attribute table, you can create a profile graph with the built-in graphing tools of ArcGIS.
- In ArcMap, select View> Graphs> Create graph and select the Vertical Area graph option. Set Layer/Table to the attribute table and set Value field to the Point_Z attribute and X field to Point_M.
- Complete the Graph wizard to finish creating the profile graph.
An example profile graph in ArcMap might look similar to the following:
This technique shows how to create a profile graph in ArcMap. If you have access to ArcGIS Online, two other ways to create them are with the elevation Profile template and the elevation Profile Add-in.