Elevation Data Sources
Elevation GIS and CAD data comes in many forms, formats, and from many sources. The most accurate and useful elevation data for locations in North Carolina are LIDAR-based products discussed in the seperate section below.
A valuable online (publically available) source of raster-based or grid elevation data for locations outside of North Carolina is the USGS National Map. It has the following elevation data products available at US and International extents:
The USGS also provides Web Map Service (WMS) links for Elevation data.
For NCSU affiliates, there are many elevation data sources including worldwide SRTM, GTOPO, and NED, on the Geodata Server, mostly from the ESRI Data and Maps collection. Click Here to execute a search for available data with the keyword "elevation."
Vector Contour LinesVector contour line data is often useful for visual or analytical purposes. Many local governments provide these data at varying contour intervals, for download from their websites. Click here for North Carolina local government GIS websites. Check both the "Lib Web" and "Dwnld" links. In many cases, vector contour data is already on the Geodata Server. For example, to download contour data for a large area within the City of Raleigh from their tiled interface would take much longer than downloading this single geodatabase.
An alternative option for locations in North Carolina is to use NC DOT's contour data, discussed near the bottom of this webpage. For locations outside of NC, either search Google for locally maintained data, or contact Data Services to discuss your need.
LIDAR Based Elevation Data for North Carolina
Following Hurricane Floyd's flooding damage, North Carolina embarked on a joint effort with FEMA to re-map the state's flood zones. A by-product of this work is detailed elevation data collected by airborne LIDAR sensors. (NOTE: Raw pre-processed LIDAR data can be obtained from the USGS CLICK website for research needs.)
For more information about the NC Floodplain Mapping Program (NCFMP), and full documentation on the LIDAR data collection process, go to http://www.ncfloodmaps.com.
A LIDAR workshop was hosted by NCSU on August 4, 2004, and it's website has presentations and links to LIDAR data activity in NC that were relevant at that time.
NC LIDAR data as viewed on the seamless.usgs.gov website. NED 1 arc second (30m) data is being shown for surrounding states.
Elevation data derived from LIDAR are available for North Carolina from the following sources:
NC Sparta Server
From the download window, you may download by county data listed below. (Some data for some counties are not available for various reasons). If you only need a small portion of a county, you may want to only download the necessary files. To determine the file names of what you'll need, you must download the ELEVGRID shapefile by clicking the "Terrain Data Grids" link.
Download Tip: To download many files in one batch process, such as may be needed for getting a lot of the LIDAR data zip files for example, try a Firefox extension such as DownloadThemAll!.
Note: The coordinate system for these downloads is NC Stateplane, NAD 83, feet, and elevation values are in feet.
County 20' DEMs
As of November 2007, this is an incomplete collection. The graphic below shows which counties are available. In addition to the counties shown below in the graphic, the following counties are available: Alexander, Alleghany, Caswell, Columbus, Davie, Graham, Robeson, and Stokes.
The files may be downloaded from http://geodata.lib.ncsu.edu/dem/nc_20f (publically accessible). There is a zip file for each county, which contains an .asc file, .prj file, and .xml metadata file. The .asc file must be converted to a raster using the "ASCII to Raster" conversion tool with the "Float" option.
Usage Tip from Tom: The floating point grids will require much more computer "horsepower" than the integer grids from DOT, discussed below. A work-around is to apply a constant of perhaps 10,000 to the floating-point values, and thus keep the attribute (elevation) precision.
NC Dept. of Transportation, GIS Unit
Also available from their website are Hillside Shade grids, Slope grids, and Contour vector data. FAQ's and further documentation are there too.
USGS National Map
NOAA Coastal Service Center, Digital Coast
NCSU Campus Elevation Data