CLOSE RANGE DIGITAL PHOTOGRAMMETRY TECHNIQUES APPLIED TO LANDSLIDES MONITORING
This paper deals about 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 improved in a test area (a slope along a road with instability processes in southern Spain) where terrain failures have been documented in the last ten years. Several photogrammetric techniques were checked as well as combination of both convergent (for calibration and densification) and stereoscopic (for DTM generation) networks. Considerations about the use of terrestrial LIDAR and a comparative example are also made. This paper is included in a wider research project carried out in Northern and Southern Spain for study landslides. This research project (MAPMUT: The improvement of susceptibility analysis by means of useful digital models of the terrain geometry), aims with an improvement of susceptibility maps using high quality input information.
Landslide monitoring by fixed-base terrestrial stereo-photogrammetry
Abstract. Photogrammetry has been used since long to periodically control the evolution of landslides; however, true monitoring is reserved to robotic total stations and ground based InSAR systems, capable of high frequency, high accurate 24h/day response. This paper presents the first results of a fixed terrestrial stereo photogrammetric system developed to monitor shape changes of the scene. The system is made of two reflex cameras, each contained in a sealed box with a control computer that periodically acquires an image and send it to a host computer; once an image pair is received from the two cameras, the DSM of the scene is generated by image correlation and made available for archiving or analysis. The system has been installed and is being tested on the Mont de la Saxe landslide, where several monitoring system are active. Some instability of the camera attitude has been noticed and is corrected with an automated procedure. First comparisons with InSAR data show a good agreement.
DIGITAL AND ANALYTICAL PHOTOGRAMMETRIC RECORDING APPLIED TO CULTURAL HERITAGE. A CASE STUDY: "St. DOMINGO DE SILOS' CHURCH (XIV th CENTURY, ALCALA LA REAL, SPAIN)"
This paper is about a complete photogrammetric record of St. Domingo de Silos’ Church (XIV th century), in Alcala la Real (Jaen, Spain). It was declared National Monument in 1931. At present it is a ruin heavily damaged and near to collapse. So, local authorities have decided urgent actions for the reconstruction. Previous to the restoration works, different surveying and photogrammetric techniques were used for a reconstruction project and cataloguing of an important historical building, but at moderate costs with the extensive use of non metric and semi-metric instrumentation. A wide variety of photogrammetric methods and instruments has been applied: analytical and digital plotters; terrestrial metric, semi-metric (reseau plate) and non metric cameras (analogical and digital). Stereoscopic pairs, when possible, were taken with the help of a device which allowed for stereoscopic shots. Convergent photographs were also taken in order to reach a favourable geometry for bundle adjustment (selfcalibration) and control point densification. Both photogrammetric and desktop scanners were used. To maintain low costs, the main final products, in case of planar surfaces, were mosaics of rectified photographs. Cross sections, modelling and structural analysis of deformation of walls and a vault were also made in order to support the final architectural restoration project.