Our Products/Services
Remotely Sensed Ground Control Points

TerraSAR-X orbital accuracy and precise radar metrics enable space-based Ground Control Point collection World-Wide

CompassData offers Remotely Sensed Ground Control Points (RSGCP™), providing control for those areas that are too remote, or too dangerous, for field data collection crews to go in person or where on-ground GPS surveys are not possible.

The Remotely-Sensed GCP data are delivered to the customer in the same fashion as CompassData terrestrial GPS control points, including:

  • an Image Chip corresponding with the SAR Image Chip for the control point
  • a Metadata file in CSV format
  • a SHAPE file for the Area of Interest
  • a KML file for viewing in Google Earth™
  • an Accuracy Report and a Site Sketch providing additional details regarding the RSGCPs

To complement CompassData’s archive of terrestrial GPS collected GCPs, we are working with Infoterra GmbH, as an authorized reseller, using the new Synthetic Aperture Radar (SAR) sensor technology, combined with an extremely precise on-orbit platform.

Although GCPs collected by terrestrial means typically offer higher accuracies, this spaceborne approach is a significant milestone in control.

This is possible through:

  • A very high degree of orbital accuracy of the TerraSAR-X satellite, (residing in the centimeter range)
  • Very precise radar beam tracing
  • Extremely high resolution capabilities of the satellite and the resulting high geolocation accuracy of the SAR imagery (<1m in Range and Azimuth for two collection modes)

The sensor is highly suited for collecting precise and accurate 3D ground information regardless of weather or daylight conditions.

Infoterra follows the accuracy standards established by CompassData Inc. to provide data collection in two standard offerings:

  • RS-1 Precision: Based on 3-4 High Resolution SpotLight scenes, 5 GCPs at <=1m accuracy can be generated within an area of 20 km2
  • RS-2 Precision: Based on 2 StripMap scenes, 8 GCPs at <=3m accuracy can be generated within an area of 1,000 km2

Google image

Image courtesy of Google Earth

Our RSGCP provide a guaranteed accuracy of less than or equal to 1 m.

The accuracy of 3D ground control points retrieved from TerraSAR-X SpotLight and StripMap images have been evaluated by validating the RSGCP coordinates against Differential GPS control points and/or a highly accurate LiDAR DEM on varied test sites, all situated in challenging terrain. Nevertheless, as RSGCP accuracy strongly depends on terrain conditions and identifiable points, feasibility studies of each Area of Interest are performed. For detailed information regarding the accuracy of Remotely-Sensed GCP data, please contact us directly.