Levels of Mapping Accuracy

Satellite mapping is a practical solution for obtaining topographical information over extremely large areas.

Mapping Accuracy

Accuracy is influenced by the density of GCPs and the type of satellite used. Satellite mapping typically has a vertical accuracy of around 1.5 m to 3 m. If you have existing topographical data, we can combine it with our mapping data.

Mapping vs. Surveying

In contrast, satellite surveying is better than 15 cm RMSE in vertical accuracy. Satellite surveying sees applications in earthworks construction and operating mines. See Satellite Surveying.

Mapping without Ground Control Points (GCPs)

When your project requires it, we can complete satellite mapping projects with few GCPs or none. Even with no GCPs, PhotoSat elevation maps are still reliable. See below.

For areas of 100 km2:

Level of Accuracy GCPs (per 100 km2) Over Horizontal Distance Satellites Applications
1.5 m (absolute) <5 10 km ALOS PRISM



Preliminary exploration

Terrain assessment Feasibility studies

3 m (absolute) <5 10 km SPOT 6


Preliminary exploration

Terrain assessment

Feasibility studies

Proprietary PhotoSat models of the systematic distortions in stereo satellite photos

PhotoSat has developed proprietary models of the systematic distortions in the photos for most types of commercial stereo satellite systems. We have measured and characterized these systematic distortions in our test areas. The use of these models in our satellite processing is an essential component of the PhotoSat surveying accuracy.

Adjusting systematic distortions in the stereo satellite photos

To achieve the best possible PhotoSat surveying accuracy, PhotoSat identifies and adjusts the distortions in the satellite photos. We apply our models of the systematic distortions of each type of satellite photo as follows:

  • Identify and attenuate distortions in individual stereo pairs of satellite photos
  • Use overlapping areas of the stereo satellite photos to identify and attenuate distortions in each of the photo pairs.
  • Use ground survey points establish global location and to identify and attenuate specific types of distortions not attenuated in steps 1 and 2.

For more information see the following:

The Accidental Discovery of a New Way to Produce Accurate Elevation Surveys from Satellite Photos
Are PhotoSat Satellite Surveys Really More Reliable Than Ground Surveys?
How Can Modern Satellites Photos Possibly Be Accurate To 20 Centimeters In 10 Kilometers?