• Christian Øster Pedersen
The report deals with digital terrain modelling by means of oblique images from four different direction of shooting, north, south, west and east. The report is divided into two processes, production and control. The production deals with orientation, production of the height models by means of matching, filtering of height models and interpolation of gaps. Five terrain models are produced, one for each direction of shooting and one combined. The terrain models are compared to an existing 2x2 m terrain model, and different factors influence on the accuracy and completeness are analysed. The best of the five terrain models is furthermore compared to GNSS RTK measured checkpoints for three different area types, open areas, near buildings and forest areas. The production has been influenced by the fact that the program (Z/I ImageStation) for the orientation and production of the height models not are designed for oblique images. Therefore it was necessary to make some adjustments, which has made the production more difficult. Furthermore the advantages of the oblique images are not used fully. It’s conclude that following factors have the most influence on the accuracy and completeness, the filtering, the interpolation of gaps and the combination of height data from four direction of shooting. Overall the filtering is performed satisfying, but there are some problems in the edges of the models. The interpolation of gaps is associated with uncertainty, because the greatest errors are located in the interpolated areas. Furthermore the accuracy increases when the interpolation have been performed. The combinations of height data from the four direction of shooting compensates for dead areas, which often are seen in a height model from only one direction of shooting. Furthermore the combination improves the accuracy and completeness. The accuracy (RMSE) in the combined terrain model is 0,55 m compared to the existing terrain model, and the accuracy in the three areas are 0,44 m in open areas, 0,19 m near buildings and 0,47 m in forest areas.
Publication date2009
Number of pages118
Publishing institutionInstitut for samfundsudvikling og planlægning
ID: 17683546