High-resolution mapping and visualization of a climbing wall

Abstract

Many cartographers are making an effort to depict mountainous steep relief on classical maps. There are many techniques that enable achieving this goal effectively. However nowadays we notice a trend toward 3D realistic representation of relief, using Digital Elevation Models (DEMs) derived from aerial photographs or satellite imagery. They are very useful and sufficient for visualizing and modeling various terrain features – from flat to hilly. Nevertheless the mountainous terrain is very problematic, as very steep slopes cannot be seen and depicted from bird’s eye view. That is why an alternative method should be used to gather information and visualize terrain with vertical relief, otherwise information about such areas is omitted or very poor (Butler et al. 1998; Gooch et al. 1999; Buchroithner 2002; Mergili 2007). The paper presents a possible application of close-range photogrammetry for mapping and visualization of steep (close to vertical) rock walls. In this way integration of photogrammetry, digital cartography and photorealism meets the needs of information systems for climbers and tourism in general. Technology and software is similar to that being used in aerial photogrammetry, but some differences in concept should be considered in order to generate spatial model in horizontal projection, so called quasi-DEM. The research object is a part of natural climbing wall situated in Krakow, Poland. The surface is approximately vertical, with some parts which are overhung. It is also very rough, so many shades appear. For the creation of quasi-DEM, quasi-orthophoto and virtual rock face, 4 overlapping photographs were taken with Nikon D80 amateur digital camera. Object distance was about 5.5 m, and ground resolution about 1.8 mm. The camera was previously calibrated with ImageMaster software by Topcon and known parameters of the camera lens allowed the removal of the distortion from the images. ERDAS LPS (Leica Photogrammetry Suite) was used to perform photogrammetric processing. In order to demonstrate the potential of the technique, some steps used by climbers are marked, and anaglyphic methods facilitate a three dimensional perception. That can help inexperienced climbers to plan their route and prepare for the real experience.