|
|
|
|
|
|
|
|
GTN-01 General contributions to new methods and technologies
|
|
|
|
Slope instability evolution by close range photogrammetric techniques
|
|
|
|
Javier Cardenal, Universidad de Jaén (Spain)
Emilio Mata, Universidad de Jaén (Spain)
José Luis Pérez García, Universidad de Jaén (Spain)
Jorge Delgado, Universidad de Jaén (Spain)
M. Angeles Hernández, Universidad de Jaén (Spain)
José Ramón Diaz de Terán, Universidad de Cantabria (Spain)
Juan Remondo, Universidad de Cantabria (Spain)
Alberto González Díez, Universidad de Cantabria (Spain)
|
|
|
|
This paper is included in a Spanish research project MAPMUT (GGL2006-05903/BTE) that is focuses in the improvement the prediction capacity of landslide hazard maps, clearing some uncertainties contained in susceptibility maps. These uncertainties remain because lack of reliability and resolution of the DEM's usually employed in such maps. At present, the project is under progress and the spatial input information is being generated by means of digital photogrammetric techniques (both digital aerial and terrestrial cameras) combined with aerial and terrestrial LIDAR.
The paper aims with the use of non metric reflex digital cameras in landslide monitoring and the analysis of landscape evolution from comparison of present digital photographs and old digitized analogue metric terrestrial photographs. The methodology has been set in a test area (a slope along a road with instability processes) where terrain failure has been documented in the last ten years. With respect to digital non metric reflex cameras, last decade has seen an increasing use of this off the shelf instrumentation for use in low cost applications in earth sciences and environment. The important rise in image resolution (up to 14 Mb), the dropping prices and easy direct image acquisition are the main responsible for the attractive use of this instrumentation. Also the use of present low cost digital photogrammetric systems (both stereoscopic and convergent stations) has contributed to the use of these cameras among photogrammetrist and non photogrammetrist.
In this paper a Canon EOS D5 digital reflex camera (12.8 resolution) has been used. Data reduction methods were convergent networks (although combined with some stereoscopic shots in order to allow the use of a Digital Photogrammetric Workstation -DPW-) processed with camera selfcalibration. The selfcalibration has allowed obtaining the inner camera parameters but also the densification of the control/check points network.
On the other hand, there were available some old metric analogue photographs (dating from 1998) taken with an UMK 1318/10. Photographs were digitized with a photogrammetric scanner. These photographs correspond to a previous study of this landslide for evaluation of photogrammetric techniques for monitoring slope deformations. A comparison between both epochs has been made allowing the quantitative estimation of the slope changes, expressed as different sections and volume variations. Additional considerations about the use of metric or non metric instrumentation are made in the paper.
Finally, the work has been completed with an evaluation of terrestrial laser scanner for validation of obtained data and development of additional methods for monitoring landslides. Detailed DSM of the slope were obtained and compared to those from digital camera. The employed scanner was the Optech Ilris 3D combined with the I-Site Studio software for processing the raw data.
|
|
|
|
|
|
|
|
|
