Qualitative and quantitative photogrammetric techniques for multi-temporal landslide analysis

A. Zanutta, P. Baldi, G. Bitelli, M. Cardinali, A. V

Abstract


The results of two survey methods, geological photointerpretation and historical photogrammetry, are compared
in order to evaluate the temporal evolution of a unstable slope located in the Tuscan-Emilian Apennines (Italy).
Historical aerial photos of the area, derived from photogrammetric surveys conducted in 1954 (scale 1:60000),
in 1971 (scale 1:20000), and in 1976 (scale 1:17000) were available. A photogrammetric flight was further conducted
in 2000, at a scale of 1:4400, with a traditional GPS ground survey support. First, the results of photographic
analysis with the photointerpretation method are presented: the landslides are described from a geological
point of view, showing its temporal evolution. To quantitatively assess the landslide movements, Digital Terrain
Models were generated by means of an analytical plotter and a digital photogrammetric workstation, with
semi-automatic and automatic procedures. To generate these products, it was necessary to solve problems related
to a lack of data concerning the aerial cameras used for the historical flights (internal orientation) and the difficulty
identifying control points on the photos in order to define the external orientation. An unconventional
photogrammetric methodology, based on identification of homologous points in zones considered outside the
landslide area, has been there developed and tested to insert the various surveys into a single reference system.

Keywords


photogrammetry;DTMs generation;archival photographs;surface representation;landslide analysis

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References


DOI: https://doi.org/10.4401/ag-3117

Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X