(As with SRTM1 data, additional files can be added upon request.) ASTER has good 30-meter coverage of the entire world, but the massive size of the database makes it impractical to store all of it on. The ASTER GDEM ( tech specs & download links) is a joint product of NASA and the Japanese Ministry of Economy, Trade, and Industry (METI). In most locations, they are more accurate than SRTM1 files. Most of the files are a combination of SRTM1 and local LIDAR and/or survey data, and they have a horizontal resolution of 1 arc-second (about 30 meters north-south and 20 meters east-west). These are high-quality digital elevation files from Western, Northern, and Central Europe and Iceland which have been copied to GPS Visualizer's server. Additional locations may be installed upon request.ĭigital 1-arcsecond terrain models of European countries, compiled and resampled by Sonny formerly hosted by Austria's OpenDataPortal and currently available at. GPS Visualizer's server does not contain the full global dataset, but it does contain all of Europe, Central America, Japan, South Korea, Taiwan, and New Zealand, as well as most of Australia and parts of South Africa. Previously, SRTM1 data was only available for the United States (and was not very useful because NED1 is generally better), but now NASA has released SRTM1 tiles for the entire world. NASA's SRTM1 database (from the Space Shuttle Radar Topography Mission) has a resolution of about 30 meters. USGS also produces 1/3-arc-second data (NED13), but because those files are nine times larger than NED1 files, only a few mountainous areas (Cascade Range, Sierra Nevada, southern Utah) are available on GPS Visualizer.

For Alaska, 60-meter data is also available (NED2). 1 arc-second (~30-meter) horizontal resolution is available in most areas (NED1). Geological Survey's excellent National Elevation Dataset covers the United States, Canada, and Mexico. If GPS Visualizer runs into one of these, it will not overwrite those elevations in your input data.) DEM data sources NED (USGS) (Speaking of gaps, there are a few in NASA's SRTM data, and that's unavoidable. Often, this is desirable profiles made with DEM data are usually 'smoother' looking than GPS, and typically contain fewer gaps or suspicious readings. Note that the elevation-adding feature will erase any existing altitude data (for example, from a GPS) that might already be in your file. Complete copies of the SRTM3 and USGS NED databases, as well as a large number of SRTM1 and ASTER tiles, are stored on GPS Visualizer's server - that's more than 250GB of raw data. Or, look in GPS Visualizer's various input forms for the menu called 'Add DEM elevation data,' and choose one of the elevation databases (described in the table below).

Resolution calculator in arc seconds