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  4. Adding an Elevation Layer
  1. Home
  2. Knowledge Base
  3. GeoHECRAS
  4. Adding an Elevation Layer
  1. Home
  2. Knowledge Base
  3. Importing Data
  4. Adding an Elevation Layer

Adding an Elevation Layer

CivilGEO’s software can construct an elevation terrain surface from online elevation data sources or through a local elevation data file.

Adding Online Elevation Data

CivilGEO’s software can utilize elevation data directly from either the USGS or NASA elevation data servers:

  • US Elevation (10m)USGS: Accesses the elevation data from the USGS National Elevation Dataset (NED) data server. Elevation data with a resolution of 10m is confined to the area within the borders of the United States. Different parts of the United States have different elevation resolutions. The National Elevation Dataset (NED) is the primary elevation data product of the USGS, and is a seamless dataset with the best available raster elevation data of the conterminous United States, Alaska, Hawaii, and territorial islands.
  • World Elevation (30m)NASA: Accesses the elevation data from the NASA elevation data server. Elevation data with a resolution of 30m, derived from the Shuttle Radar Topography Mission (SRTM) data. Different parts of the world have different elevation resolutions. The SRTM obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. The SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February 2000.

To add the online elevation data from the USGS or NASA Elevation Data Server, follow the steps below:

  1. Right-click on the Map Data Layer panel and select Add Elevation Layer from the displayed context menu.
  2. The Add Elevation Layer dialog box will be displayed.
    Add Elevation Layer dialog box
  3. Select the Online Elevation Data tab.
  4. Check the Use online elevation data source checkbox.
  5. Click the [OK] button.
  6. The software will start to pull elevation data tiles from the selected elevation data source in order to construct an elevation terrain surface.
  7. Alternatively, you can download the data on the local computer as an elevation grid DEM. Choose the Download Elevation DEM tab. You can then specify the boundary limits and where the DEM file should be saved.
    Download Elevation DEM

Note that the elevation DEM data that is downloaded using this command has a resolution of 10 meters in the USA and Canada, and 30 meters everywhere else. In comparison, the USGS National Map website has DEM elevation data of 10 meter, 3 meter, and 1 meter resolution, although availability varies. The user needs to zoom into an area and see the elevation data that the USGS provides, which is constantly being updated as the USGS collects and uploads more elevation data to their elevation data server.

Additionally, keep in mind that in a region where 1 meter data is available, 3 meter data is not available. Similarly, where 3 meter data is available, 1 meter data is not available.

For example, the USGS lists 10 meter elevation data available everywhere in the USA.
USGS 10 meter elevation data

3 meter elevation data is available in the regions shown below.
3 meter elevation data

1 meter elevation data is available in the regions shown below.
1 meter elevation data

Adding Local Elevation Grid Data

CivilGEO’s software supports most major elevation grid data file formats, such as:

  • ArcInfo ASCII Elevation Grids
  • ArcInfo Binary Elevation Grids
  • GeoTIFF Elevation Grids
  • USGS DEM Elevation Grids
  • USGS NED Elevation Grids – BIL Format
  • USGS NED Elevation Grids – Float Format

To add elevation data using a local elevation grid data file, follow the steps below:

  1. Right-click on the Map Data Layer panel and select Add Elevation Layer from the displayed context menu.
  2. The Add Elevation Layer dialog box will be displayed.
    Add Elevation Layer dialog box
  3. Select the Local File Elevation Data tab.
  4. Click on the […] file browse button and select the elevation grid data file to load.
  5. Click the [OK] button.
  6. The software will load the elevation grid data file as an elevation terrain surface.

Using Other Elevation Data

Other local elevation data files can be processed within the software to create an elevation terrain surface. This includes:

  • ArcInfo Contour Shapefiles
  • ArcInfo Elevation Point Shapefiles
  • ArcInfo GDB File Geodatabases
  • ArcInfo MDB Personal Geodatabases
  • AutoCAD Civil 3D Terrain Surfaces
  • AutoCAD Contours
  • Bentley MicroStation Terrain Surfaces
  • Bentley MicroStation Contours
  • LandXML Terrain Models
  • XYZ ASCII Point Terrain Data

Civil 3D and Bentley MicroStation terrain surfaces imported as LandXML terrain models.

About the Author Chris Maeder

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