- 174km2 surveyed using 153 ground reference survey point
- This WorldView-1 satellite elevation survey is accurate to 14cm RMSE, determined by comparison to 7,343 elevation check points from a highly accurate LiDAR survey
- June, 2010 WorldView-1 stereo satellite photos processed by PhotoSat in October, 2016
Summary report below:
Gerry Mitchell, P. Geo, Geophysicist, President PhotoSat
A 1m grid of elevation values, covering an area of 174 square kilometres, was produced over a PhotoSat test area in California. The elevation grid was made using geophysical processing of 50cm ground resolution stereo satellite photos taken by the DigitalGlobe WorldView-1 satellite. The stereo satellite elevation processing was referenced to 153 ground survey point. The elevation surveying accuracy was determined by direct comparison to 7,343 elevation checkpoints extracted from a highly accurate LiDAR survey.
The Garlock Fault was surveyed with LiDAR in April, 2008 by OpenTopography. The location of the LiDAR survey and the area of this WorldView-1 stereo satellite survey accuracy study is shown below. We believe this LiDAR survey data to be accurate to better than 5cm RMSE.
California elevation grid:
PhotoSat produced a 1m grid of elevations over the entire project area. We processed the stereo WorldView photos with our geophysical stereo satellite processing system in October, 2016.
Ground reference points:
With this study we are demonstrating the satellite surveying accuracy we can produce with stereo WorldView-1 when we have lines of survey points. We extracted a total of 153 survey points over level areas on the LiDAR data. These points lie along two lines as shown in the figures above. This distribution of survey points is typical of the survey points for source and receiver locations for 2D seismic surveys used in Oil and Gas exploration.
Global shift of stereo satellite survey to match ground reference:
The WorldView ortho photo and elevation grid needed a constant shift of only 0m E, 1.75m N and 4.34m in elevation to match the LiDAR data. The global accuracy of most WorldView stereo satellite photos is better than 3m.
Accuracy evaluation checkpoints:
The accuracy of the PhotoSat 1m survey grid was evaluated with 7,343 elevation checkpoints derived from the LiDAR elevation grid.
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 7,343 elevation checkpoints with slopes less than 20% grade have an RMSE of 14cm.