Context and objectives
The present study forms a contribution to a GIS methodology for the mapping of remote areas characterised by scant ground truth, i.e. those areas where the extraction of information of satellite imagery, as compared to classical photogram metrical techniques, proves most relevant. Two aspects of this GIS methodology are discussed :
- The automatic extraction of a DTM from stereoscopic SPOT Imagery.
- The automatic selection of a GIS projection framework.
Expected scientific results
- A satellite model for the automatic extraction of a DTM from stereoscopic SPOT imagery was developed, which realises an accurate mapping between image and terrain co-ordinates. This test case shows that the method presented, which can be applied by using only a few reference points, produces results which are comparable to similar studies based on a significantly greater number of reference points.
- A heuristic method was developed for the selection of a suitable co-ordinate system starting from a small number of carefully chosen map projections. The proposed strategy requires an efficient co-ordinate transformation scheme. It was shown how general and conformal polynomial approximation significantly increases the efficiency of the transformation while taking into account the required planimetric accuracy.