DEVELOPMENTS IN PHOTOGRAMMETRY - THE GEOMORPHOLOGICAL POTENTIAL

Current emphasis in geomorphology recognizes the need for the accurate representation of topographic form, reflected in the growth of digita l terrain and elevation modelling. A key requirement of such strategie s is the efficient acquisition of information in an appropriate form a nd at an appropriate resolution to the landform under consideration. T he traditional use of photographs in geomorphology has been for interp retation, but developments in photogrammetry may allow the full advant ages of the photograph as a means of acquiring and storing quantitativ e information to be used. The photograph can provide information on al l areas visible on a photograph; the information is acquired retrodict ively; the photograph preserves the spatial relationship of morphologi cal units; the collection of photographs requires minimal landform con tact; the photograph records extra explanatory information; and photog raphs can be obtained at an appropriate temporal resolution to the lan dform under investigation. However, optical and mechanical limitations imposed by traditional photogrammetric approaches have prevented its rigorous and widespread application to geomorphology. Developments wit hin photogrammetry, notably the analytical approach, now open up wider geomorphological possibilities. The analytical approach overcomes the se limitations through the use of an interactive mathematical model at the stage of photographic analysis. The obtained information is in a form directly suited to the construction of digital terrain or elevati on models. This technique can be used both for landform monitoring and for the analysis of archival photographs to reconstruct historical la ndform change.