Spot revisited: Accuracy assessment, dem generation and validation from stereo spot 5 HRG images

Buyuksalih G., Kocak G., Topan H., Oruc M., Marangoz A.

PHOTOGRAMMETRIC RECORD, vol.20, no.110, pp.130-146, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 20 Issue: 110
  • Publication Date: 2005
  • Doi Number: 10.1111/j.1477-9730.2005.00314.x
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.130-146
  • Keywords: automatic image matching, DEM generation and validation, geometric, accuracy testing, SPOT 5 HRG Level 1A and 1B stereo-images
  • Istanbul University Affiliated: No


SPOT 5 HRG Level 1A and 1B stereo scenes covering Zonguldak tesfield in north-west Turkey have been analysed. They comprise the left and right image components with base to height ratio of 0-54. The pixel size on the ground is 5 m. The bundle orientation was executed by the PCI Geomatica V9.1.4 software package and resulted in 3D geopositioning to sub-pixel accuracies in each axis provided that at least six control points were used in the computation. Root mean square error (rmse) values and vectors of residual errors for Levels]A and 1B are similar even for different control and check point configurations. Based on the scene orientation, Level 1A and 1B digital elevation models (DEMs) of the testfield have been determined by automatic matching and validated by the reference DEM digitised from the 1:25 000 scale topographic maps, interferometric DEMs from Shuttle Radar Topography Mission (SRTM) X- and C-band SAR data and the GPS profiles measured along the main roads in the testfield. Although the accuracies of reference data-sets are too similar to the generated SPOT DEMs, these are the only high quality reference materials available in this area. Sub-pixel height accuracy was indicated by the comparison with profile points. However they are in favourable locations where matching is always successful, so such a result may give a biased measure of the accuracy of the corresponding DEMs.