The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000.

SRTM data were processed from raw radar echoes into digital elevation models at the Jet Propulsion Laboratory (JPL) in Pasadena, CA. These original data files had samples spaced ("posted") at intervals of 1 arc-second of latitude and longitude (about 30 meters at the equator). These data were then edited by the National Geospatial Intelligence Agency (NGA, formerly the National Imagery and Mapping Agency), and distributed as part of their DTED® product set.

The editing, also referred to as finishing, consisted of delineating and flattening water bodies, better defining coastlines, removing "spikes" and "wells", and filling small voids. This "finished" set is publicly available at two postings: 1 arc-second for the United States and its territories and possessions, and 3 arc-seconds for regions between 60 degrees North and 56 degrees South latitude.

The National Elevation Dataset (NED) is a seamless mosaic of best-available USGS elevation data. Full coverage exists in 10-meter and 30-meter resolution for the conterminous United States. The new LiDAR-derived NED at 3-meter resolution is rapidly being produced for the full country and US territories and protectorates as well.

The 7.5-minute elevation data for the conterminous United States is the primary initial source source data for the 10- and 30-meter data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at the quadrangle seams. One of the results of the NED processing is a much improved base of elevation data for calculating slope and hydrologic derivatives.

MapMart offers DEMs in the following formats: USGS DEM, Vertical Mapper GRD, DXF Mesh, Point and 3D Face, GeoTIFF, ASCII XYZ, RockWorks, Terragen, Surfer Grid (Binary or ASCII) and others. Some of these formats are available for immediate download by seamless custom area upon submittal of credit card and others can be generated at additional cost.

Geospatial elevation data set are utilized by the scientific and resource management communities for global change research, hydrologic modeling, resource monitoring, mapping, and visualization applications.

A SPOT DEM is a digital elevation model produced by automatic correlation of stereopairs acquired by the High Resolution Stereoscopy (HRS) instrument on SPOT 5. Unlike a digital terrain model (DTM), which describes the distribution of terrain or "bare earth" heights, a DEM includes "first surface" elevations with vegetation and man-made structures. A SPOT DEM has a post spacing of one arc second or 20 meters.

With more than 100 million square kilometers already covered across 2/3 of the globe's land surfaces, SPOT DEM is the ideal solution to ensure rigorous registration of all your data.

SPOT DEMs significantly improve registration of data layers in digital mapping. They also are therefore widely used in geographic information systems (GIS) for land management and terrain modelling. Applications include: impact studies, rail and road infrastructure studies, mobile telecommunications engineering, structural geology surveys, oil exploration, erosion studies, mapping, flight simulation. A SPOTView Ortho can be draped over a SPOT DEM for a more realistic 3D view of terrain, which helps multidisciplinary teams to work more closely together.

Digital Elevation Models (DEMs) are digital files consisting of points of elevations, sampled systematically at equally spaced intervals. MapMart sells DEMs in the following formats: USGS DEM, Vertical Mapper GRD, DXF Mesh, GeoTIFF, ASCII XYZ, Arc ASCII Grid, RockWorks, Terragen, and Surfer Grid (Binary or ASCII). Some of these formats are available for immediate download by quads or by seamless custom area upon submittal of credit card, others can be generated at additional cost.

The default projection is UTM for 7.5' DEMs (the majority being in NAD 27) and Latitude/Longitude WGS 72 for 3 arc second DEMs with coordinates being in decimal degrees. Texture Maps can also be purchased with each DEM.

Anywhere in the world that a satellite can collect stereo imagery, MapMart can create accurate and detailed elevation and contour data. These data are not available of-the-shelf anywhere in the world so MapMart has developed the methodology to create it quickly and with unrivaled quality.

A satellite task for stereo coverage often takes 2-4 months to successfully complete, possibly longer in heavily clouded areas. Once the imagery is captured, MapMart quickly, accurately and photogrammetrically creates the surface data from the stereo imagery. MapMart then edits out and removes the vegetation and man-made structures from the model to deliver a true bare earth product.

Once the bare earth model is complete, MapMart then creates the tightest contour interval allowed by terrain. 1 meter and 2 meter intervals are possible for many areas.

To further improve the data accuracy, MapMart can arrange custom ground control surveys in areas where sub-meter or even centimeter accuracy is vital. Also for the ground control, we have access to an archive of worldwide GCPs to save on cost if they are found to be suitable for the project. Client-supplied survey data is always welcome as well.

There are a large number of high-resolution satellites currently in orbit with several more state-of-the-art birds set to launch from now until 2014, all with stereo capability. MapMart is partnered with and can arrange tasks on any of these satellites. The increasing number of satellites will only benefit projects of this type as it will speed imagery acquisition as well as grow the stereo archives. MapMart currently has access to the full archive of imagery for all of these satellites and can utilize less expensive archive if it is found to be suitable for the project.

From city planning to flood mapping, many industries require the use of high-resolution elevation models to complete projects. DigitalGlobe’s Advanced Elevation Series produces high accuracy Digital Surface Models and Digital Terrain Models that serve as key building blocks for successful exploration, engineering, land management, and simulation. AES allows users global access to customized models delivered directly to their desktops with numerous product configuration options for accuracy, resolution, type, and format.

The data are available in three levels of accuracy: Mapping, Precision and Very High Precision Elevation products to allow for flexibility in budget and requirements. Additional features available with these services include hydro-enforcement, road-flattening, contours, and shaded relief data.

Airbus Defense and Space’s WorldDEM™ provides a global (pole-to-pole) dataset of unprecedented quality, accuracy and coverage. The entire land surface of the earth has been captured by high-resolution radar to map the entire planet consistently, accurately, and completely providing the first standardized worldwide Digital Elevation Model. This includes remote, inaccessible and perpetually cloudy areas. The X-band radar collection method is independent of light and weather so every single place on earth is covered.

To help users take advantage of the highly precise elevation information, initially three core products will be available:

WorldDEMcore
WorldDEM core is an unedited Digital Surface Model (DSM) without any further post-processing or editing. This product usually contains radar and processing artifacts and voids.

WorldDEM™
WorldDEM is an edited Digital Surface Model with assured hydrological consistency (i.e. flattening of water bodies, consistent flow of rivers, editing of shoreline). This product is ideal for many projects including defense and security missions and oil & gas applications.

WorldDEM DTM
Digital Terrain Model (DTM) represents the bare Earth terrain when vegetation and man-made objects are removed.This product is ideal for mapping, hydrological modelling or terrain analysis.

While these three products represent the initial WorldDEM™ product offering, Airbus Defense and Space is also able to provide an expanded portfolio of additional products based on the WorldDEM™ data, including Global Ocean Shorelines, Waterbody Maps, and Global Airport / Harbor Maps.

As of September 2014, the 1 Arc second (approximately 30-meter resolution) elevation data from the Shuttle Radar Topography Mission was allowed to be released for areas outside the United States. The SRT Mission obtained elevation data on a near-global scaleto generate the first nearly complete high-resolution digital topographic database of the Earth’s topmost surfaces. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour.