- 130 km2 surveyed using only one ground reference survey point
- This Kompsat-3A satellite elevation surveying accuracy is accurate to 63cm RMSE, determined by 1,406 survey checkpoints
- October 2016 Kompsat-3A stereo satellite photos processed by PhotoSat in November 2016
Gerry Mitchell, P. Geo, Geophysicist, President PhotoSat
A 1m grid of elevation values covering an area of 130 square kilometres was produced over a PhotoSat test area in Eritrea. The elevation grid was made using geophysical processing of 50cm ground resolution stereo satellite photos taken by the Kompsat-3A satellite. The stereo satellite elevation processing referenced one ground survey point. The elevation surveying accuracy was measured with over 1,000 survey checkpoints.
Eritrea satellite photos:
The pair of stereo Kompsat-3A satellite photos over the Eritrea test area were taken on October 31, 2016 at approximately 1:40 PM local time.
Eritrea elevation grid:
PhotoSat produced a 1m grid of elevations over the entire project area. We processed the stereo Kompsat-3A photos with our geophysical stereo satellite processing system in November 2016. An image of the 1m elevation grid is shown below.
Ground reference points:
With this accuracy study we are demonstrating that we can produce highly accurate Kompsat-3A surveys with only one ground reference points. Having as little as one ground reference points for a 130 km2 satellite surveying project is not uncommon in mining exploration projects.
The location of the ground reference point is shown in the figure below. The ground reference point was a photo recognizable point.
Accuracy evaluation checkpoints:
The accuracy of the PhotoSat 1m survey grid was evaluated with 1,406 ground survey check points. These points were originally surveyed for a large mining exploration gravity survey conducted between 2004 and 2008 by MWH Geophysics. The distribution of the elevation checkpoints is in the checkpoints figure below.
The elevation check points were surveyed to an accuracy of 2 cm using Real Time Kinematic GPS survey equipment. One of the MWH Geophysics survey teams and their equipment are shown below. The accuracy checkpoints consist of a 250m by 250m regional grid of points.
Elevation survey accuracy statistics:
The Guidelines for Digital Elevation Data of the US National Digital Elevation Program (NDEP) recommends that elevation checkpoints should be chosen in areas with slopes less than 20% grade. The 1,406 elevation checkpoints with slopes less than 20% grade have an RMSE of 53cm