Reference3D

Highly accurate 3D products covering vast areas

The constitution of the Reference3D database began in 2002, with the launch of SPOT 5, with an annual production rate of 7 million km². Reference3D is a geocoded, worldwide data base, made up of 3 information layers:

DEM
These files contain a uniform grid of terrain elevation values of an area of interest and are obtained through automatic correlation of SPOT HRS stereopairs.

Sampling step: 1 second of arc (~ 30 m at the equator, varying according to latitude)
Absolute elevation accuracy: 10 m @ 90% for a slope < 20°
Absolute planimetric accuracy: 15 m @ 90%

HRS orthoimages
These images are orthorectified from the DEM and have a high degree of geometric quality and location accuracy

Absolute altimetric accuracy: 16 m @ 90%
Sampling step: 1/6 second of arc (~ 5 m at the equator - varying according to latitude)

Quality and traceability data

These are quality indicators for data sources and provide references and footprints for DEMs and orthoimages,
They describe the processing done for producing DEMs (masks),
They give accuracy estimates.

Size

Reference3D comes in geographic tiles of 1°x 1° covering emerged land areas and aligned along parallels and meridians.

The surface area of a tile, equivalent to 111 km x 111 km at the equator, decreases as the latitude increases.

Format

Reference3D comes in a DIMAP format.
The HRS DEM complies with the specifications for the level 2 DTED format.

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