Digital Elevation Model (DEM) Data Sources That You Can Get Easily
Quadrilateral Data Structure Geodetic latitude and longitude on WGS 84 ellipsoid (NAD 83) Grid cell resolution constant N-S but progressively finer E-W resolution from equator to pole
ETOPO 2 Global DEM from National Geophysical Data Center
Technical Specifications (0, 0) Row Major Order (10799, 0) 2 -byte signed integer data Worldwide Land And 5400 rows by Data Sea Elevation 10800 columns In Meters 116, 640, 000 byte dataset (3. 7 x 3. 7 km cells at equator) (0, 5399) (10799, 5399)
Clean. TOPO 2
Global Land One-km Base Elevation (GLOBE) DEM data from NGDC • 30” x 30” grid cells for the earth • Metric data for land areas, No. Data value (-500) given to sea areas
Spatial Resolution 0. 93 x 0. 93 km Cells at equator
Globe 30” x 30” grid cell data structure and tiling, format, and dataset size
USGS GTOPO 30 Global Land DEM • Integer Metric data for land areas, No. Data value (-9999) given to sea areas. • 30” x 30” grid cells for the earth. • Single GRID dataset on ESRI Data & Maps (21, 600 rows x 43, 200 cols. [1. 866 GB file])
USGS Version Has 33 Tiles
Shuttle Radar Topography Mission (SRTM) 3 arc-second (90 m) data from USGS EROS
Each grid is divided into 1 degree tiles (1200 x 1200) for land areas Grid 2
• Data are First Reflective Returns • Data Completeness Problems
Voids are Data are Filled in ESRI Compressed Maps 34 GB to and Data From 90 m SRTM Dataset 4. 33 GB
Shuttle Radar Topography Mission (SRTM) 1 arc-second (30 m) data from USGS EROS
Each grid is divided into 1 degree tiles (1200 x 1200) for land areas Grid 4
SRTM Data are also available from The National Map Seamless Server
National Elevation Dataset (NED) from The National Map Seamless Server
National Elevation Dataset (NED) Data Structure • One-second grid cells for all U. S. states except Alaska • 31 m N-S resolution • 28 m to 20 m E-W resolution • NAD 83 lat. /long. cell centers from 25° to 50° N • Full dataset is about 60 GB
Two-second Grid For Alaska • NAD 83 lat. /long. cell centers • 62 m N-S resolution • 38 m to 21 m E-W resolution from 52° to 70° N
National Elevation Dataset (NED) Data Format and Tiling Scheme
National Elevation Dataset (NED) 1/3 rd (10 m) and 1/9 th (3. 3 m) Arc-second Grids for Certain Areas from The National Map Seamless Server
You can buy the Data for each state In Arc. GIS GRID format
Light Detection And Ranging (LIDAR) Data Uses a laser and sensor to transmit and receive pulses from reflected surfaces
Post processing of the return data produces a LIDAR DEMs highly accurate DEM, available only for typically local 1 meter small with areas spatial resolution.
USGS National Land Cover Data (NLCD) 2001 1”x 1” Grid
From The National Map Seamless Server