A Comparison of Automatically Extracted Orbview-3 and Ikonos Elevation Data to Shuttle Radar Topography Mission Data

Upon completion of the SRTM project, assessing the accuracy of the SRTM elevation data and its correlation to conventional photogrammetric methods has been a focus for many research projects. To date, elevation models derived from OrbView-3 and IKONOS have not had a significant number of comparisons to SRTM data. This study attempts to quantify the relative differences between elevation data collected under the SRTM program against OrbView-3 and IKONOS digital elevation models on a common point-by-point basis. Through the use of automated tie point matching and automated elevation extraction algorithms commonly employed in commercial software, and using no ground control points, elevation datasets were created and compared. It is hypothesized that approximately a ten meter elevation difference between the three datasets will be present with IKONOS elevation accuracy being more consistent with the SRTM dataset than OrbView-3 data. Results indicate that the SRTM elevation data, relative to OrbView-3 and IKONOS, demonstrate an 8.71 and 8.62 meter difference respectively at a ninety percent confidence interval for the study site in Santiago, Chile. Mean error differences between OrbView-3 and SRTM elevations is -8.74 meters while mean error differences for IKONOS is 0.96 meters. Further investigation was performed and it was discovered by removing the “outer” one percent of data that the mean error decreases between 33% and 54% and that correlation between SRTM and OrbView-3 and SRTM and IKONOS elevation models is above 99.8%.