Mapping and visualization of the Earth’s topography and spatio-temporal change: Selected case studies of mountainous terrain.

The subject matter of this paper is the visible surface of the Earth, the Earth’s terrain. The Earth is a dynamic system. Its surface is not static but in a constant process of change through time. Endogenous and exogenous forces as also anthropogenic impact (direct and indirect) are driving elements for land surface change. Based on selected case studies of preferably mountainous terrain carried out by the author, it is intended not only to present various observation techniques for deducing relief information and its spatio-temporal change but also to show the technological progress of topographic mapping over the last two decades. The focus is clearly on remote sensing techniques facilitating area-wide coverage. Single point based geodetic measurements have also been carried out enhancing the spectrum of observation techniques. Field work has been identified as indispensable in most of the practical work. The present case studies are inherently highly interdisciplinary. Time constraints and limited financial means sometimes required unconventional solutions, which are also considered in this publication. The following geomorphologic landforms will be treated in this paper: a volcanic landscape (Chilean and Argentine Andes), badlands (Southern Italy), a glacier (Austrian Alps), rock glaciers (Austrian Alps), and a landslide (Austrian Alps). Remotely sensed data have been recorded either with space-borne, airborne, or ground-based imaging systems. This paper is primarily concerned with optical image data, however, radar data was also used where appropriate. Photogrammetric data capture on analog film is being progressively replaced by digital recording using digital sensors. Analog photogrammetric restitution apparatus was replaced by analytical stereoplotters, which in turn were finally replaced by state-of-the-art digital photogrammetric workstations. As far as digital photogrammetry is concerned, image data can be either still analog film which needs to be digitized or original digital data originating from a digital sensor, for example, a digital aerial camera. In this paper a special focus is also placed on low-priced digital SLR consumer cameras. Digital photogrammetry and modern techniques of computer vision provide new possibilities in terms of automating the image evaluation process. Bulk data can be processed, multi-ray geometry can be introduced, and stereovision capability is no longer needed. All this facilitated “democratization” of photogrammetry. The use of photogrammetric and other remote sensing techniques is no longer confined to specialists. For example, a proposal will be made on how to carry out glacier monitoring by a layperson using terrestrial “photographs” taken with a digital SLR camera. The paper is structured according to the main landforms mapped by the author in the course of time. For detailed information the reader is referred either to the references given or to the papers included in the Appendix to this document. Results of photogrammetric and geodetic work are presented numerically and/or graphically. Topographic and thematic maps were compiled visualizing the spatial (2D or 3D) information retrieved. The spatio-temporal evolution of certain processes of the Earth’s surface is sometimes best shown by computer animation. A “glacier video” has been produced in order to visualize the course of deglaciation of two small cirque glaciers located in the Austrian Alps. Small surface movements, for example of a rock glacier, can be revealed using co-registered multi-temporal image data. Surface flow/creep velocity can be retrieved from these data. Computer animations can help to visualize surface change for easy recognition by the human observer. The present publication comprises several printed maps and a CD-ROM showing the “glacier video”, as also other computer animations elaborated by the author.