The National Elevation Dataset (NED) is the primary elevation data product of the USGS. The NED is continually updated by the USGS. The NED is a seamless dataset with the best available raster elevation data of the conterminous United States, Alaska, Hawaii, and territorial islands. The NED is derived from diverse source data that are processed to a common coordinate system and unit of vertical measure. The AGRC has a statewide collection of 10 and 30 meter DEMs.
A digital elevation model (DEM) is a digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals. This is a legacy dataset and does not get updated like the NED does. The USGS produces five different digital elevation products. Although all are identical in the manner the data are structured, each varies in sampling interval, geographic reference system, areas of coverage, and accuracy; with the primary differing characteristic being the spacing, or sampling interval, of the data. The AGRC has a statewide collection of 10, 30, and 90 meter DEMs.10, 30, & 90 Meter Elevation Models (USGS DEMs)
Light Detection and Ranging elevation data is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light often using pulses from a laser. Currently this is the most accurate elevation dataset AGRC has but it is only available for a few areas of the state. In addition to the bare-earth DTMs and first-return DSMs, most LiDAR data also has point clouds of elevation information.
For more information about LiDAR visit Exploring LiDAR
AGRC has a statewide coverage of 5 Meter Auto-Correlated DEMs in addition to some 2 meter areas. The DEMs were created from the imagery collected during the 2006 NAIP and HRO aerial photography flights. The auto-correlation process is not as rigorous as other methods of elevation modeling such as photogrammetry, lidar mapping, radar mapping, etc, and therefore end-users should be aware that anomalies are expected within the elevation dataset. In comparison to the USGS NED dataset, the 2 and 5-meter DEM provides higher resolution and horizontal accuracy but anomalies are present within the data.