Improvements in 3-D digital mapping for geomorphological and Quaternary geological cartography

Abstract. In recent decades, GIS tools have been directly applied to photo-interpretative geomorphological and geological mapping. Although these tools are powerful and effective tools in the creation of digital maps, it is often very difficult to obtain a correct recognition of the nature and boundaries of geomorphological landforms using two-dimensional images. In addition, the output typically requires some improvements, usually by means of field verifications or using oblique field photographs. The aim of this paper is to present the ArcGDS™ tool, which allows the direct exploitation, visualization and digitization of stereoscopic digital linear scanned images (e.g. digital image strips, ^©swisstopo). Through two case studies, we show how 3-D digital mapping makes it possible to produce Quaternary geological and geomorphological maps with a limited complementary fieldwork approach and to provide a quantitative assessment of surface deformations through the acquisition of precise elevation coordinates. Combined with high-resolution digital elevation models, ArcGDS™ is a powerful tool, particularly over large areas, as well as under forest cover and on very steep slopes.