Conclusion

The ease of geometrical manipulation given by digital imagery provides an opportunity for researchers to expand the appeal of 2.5-D vertical and oblique photogrammetry for geological field mapping.

Software providing visualization and editing functionalities for 2.5-D geological mapping using digital aerial and oblique photogrammetric images are valuable tools to validate and compile observations gathered through field mapping. They also help to acquire new geological data where such data are either impractical to acquire, due to the expense involved, or specific rugged ground conditions. The present study indicates that a more truthful 3-D Earth Model could be rapidly constructed for a rugged area once a 2.5-D map of the geology is available. The 2.5-D map is a difficult and important step, that has not been taken into consideration in most 3-D geological modelling studies. Since most geology maps have not been constructed to closely conform to a DEM, there has to be suspicion that 3-D models constructed from these 2-D maps will lead to erroneous interpretations. In rugged areas, a 2.5-D geology map is thus necessary and needs to be closely verified through oblique visualisation and image draping methods, allied with high-resolution DEM data, to obtain optimal results at the phase of 3-D surface interpolation. Computer animations are some of the most interesting forms of geology visualisation to quickly describe and communicate the numerous steps involved in building such 3-D models because they are intuitive to the eye and simple to manipulate.