REAL-TIME EXTRACTION OF PLANIMETRIC AND ALTIMETRIC FEATURES FROM DIGITAL STEREO SPOT DATA USING A DIGITAL VIDEO PLOTTER

Precise ground coordinates in the feature extraction from raster data is a key point for their integration in geographic information systems . A method and the results of the extraction of planimetric and altime tric features from digital stereo SPOT-PLA data in stereoscopic mode a re presented. The method uses a photogrammetric approach. The stereo r estitution was done with a digital video plotter using low-cost hardwa re (PC), and comparisons of the results with digital topographic featu res (precision of three metres in planimetry and five metres in altime try) were done in the ARC/INFO environment. Results from a SPOT stereo pair (B/H = 0.74) in the Rocky Mountains (Canada) showed a planimetric accuracy of 12 metres with 90 percent confidence for well identifiabl e features and an altimetric accuracy for a DEM of 30 metres with 90 p ercent confidence. Recent improvements in the system should increase t he accuracy to 10 metres and 15 to 20 metres with 90 percent confidenc e for planimetry and altimetry, respectively.