This is the first survey ever presented in this magazine on the topic of geo-referenced data products. Eight companies responded to our questionnaire, seven from Europe and one from the US.

By Mathias Lemmens, Senior Editor, GIM International. 

What do we mean by geo-referenced data products? Firstly, these products should be deliverable off-the-shelf to costumers all around the world within a few days, either free of charge or commercially priced. The best way to explain our notion of these products is by listing examples:
- Digital Elevation Models (DEMs) derived from airborne and space-borne radar data, satellite imagery, airborne Lidar or aerial imagery
- (true) ortho-imagery derived from aerial imagery
- terrestrial imagery and Lidar point-clouds taken at street level
- 3D city models.

The products should cover substantial parts of the globe, starting from (joint) parts of continents up to the planet as a whole. They may cover either urban or rural areas, or both. Included also are data products covering specific geographical entities, such as coastal zones and mountains, on a global scale. Excluded are (1) image products such as ortho-imagery, derived from satellite imagery; these are already listed in our regular Product Survey on High-resolution Satellite Imagery, and (2) photo and map products from National Mapping Agencies (NMA).

Blom, based in Norway, responded with six products. We selected three for listing here. The other three are (1) ortho images of Denmark, Netherlands and Italy created from aerial images recorded using various digital cameras, (2) Pictometry ortho and oblique images of over 2,000 municipalities, and (3) DEM Denmark, created from airborne Lidar data.

In addition to terrestrial panoramic imagery, we list the Netherlands-based Cyclomedia, which delivers digital orthomosaicks of the entire territory of the Netherlands at 10cm resolution and delivery unit 0.5km2. Infoterra, based in Germany, will this year launch a twin satellite, TanDEM-X, to orbit in close formation with TerraSar-X. The resulting DEMs, to become available in 2011, will have similar characteristics as the here listed TerraSAR-X Stereo DEM, but global coverage will be seamless and homogeneous, accuracy improved, and the delivery unit will be km2. Remarkably, Intermap Technologies is able to derive from DEM source data of 5m x,y precision, DEM products with x,y precision of 2m. Tele Atlas, based in the Netherlands, is the only company in this survey delivering 3D city models of major cities. All products listed are in digital format.

Email: mathias.lemmens@geomares.nl