Estrazione di layer vettoriali per utilizzo cartografico da immagini satellitari ad alta risoluzione.

Le immagini ad alta risoluzione riprese dai sensori spaziali, grazie alla loro crescente disponibilità e al continuo miglioramento degli algoritmi di ortorettifica resi disponibili agli utenti finali, sembrano poter diventare in un prossimo futuro utili strumenti per la produzione e l’aggiornamento di cartografia a media-grande scala. Attualmente, le possibilità di restituzione dalle immagini satellitari sono fortemente influenzate dalla difficoltà di ottenere coppie stereoscopiche (almeno per i satelliti a più alta risoluzione) e questo, di fatto, ne limita ancora l’utilizzo alla sola produzione di cartografia 2D. Evidentemente, il prodotto cartografico che può essere ricavato per questa via è diverso rispetto alla cartografia numerica 3D ricavata con metodi aero-fotogrammetrici: la terza dimensione dell’oggetto non può essere calcolata e la dimensione del pixel dei sensori attualmente disponibili per usi civili consente la produzione di cartografia esclusivamente alle scale comprese tra 1:10.000 e 1:5.000. In questo lavoro si presenta un primo test di estrazione di layer vettoriali (edifici e strade) da immagini IKONOS pancromatiche sulla zona del lago di Lecco, da utilizzare successivamente per la produzione di cartografia alla scala 1:10.000. I layer vettoriali estratti dalle immagini IKONOS sono stati confrontati con la CTR 1:10.000 e con alcune ortofoto dell’area test, verificando l’ottenimento delle precisioni planimetriche previste per la produzione della cartografia alla scala 1:10.000

Laser scanning and data integration for three-dimensional digital recording of complex historical structures: The case of mevlana museum

Terrestrial laser scanning method is widely used in three-dimensional (3-D) modeling projects. Nevertheless it usually requires measurement data from other sources for full measurement of the shapes. In this study a 3-D model of the historical Mevlana Museum (Mevlana Mausoleum) in Konya, Turkey was created using state-of-the art measurement techniques. The building was measured by terrestrial laser scanner (TLS). In addition, some shapes of the indoor area were measured by a time-of-flight camera. Thus, a 3-D model of the building was created by combining datasets of all measurements. The point cloud model was created with 2.3 cm and 2.4 cm accuracy for outdoor and indoor measurements, and then it was registered to a georeferenced system. In addition a 3-D virtual model was created by mapping the texture on a mesh derived from the point cloud

A Sustainable Approach for upgrading geographic databases based on high resolution satellite imagery

The availability of high-resolution satellite images could be exploited for upgrading geographic databases at medium scales (1:5,000-1:25,000) as alternative to aerial photogrammetry. The paper presents a procedure to carry out this task which is based on an automatic image-to-image registration procedure of new satellite data to existing ortho-photomaps that have to be upgraded. In order to get a regularization of control points extracted in automatic way, a technique implementing a neural network algorithm is applied. Once an image has been georeferenced, this can be ortho-corrected thanks to a DTM (nowadays available in almost all developed countries). However, the product which is obtained so far is still a raster maps. To cope with the increasing need of vector data in geographic geographic databases, some tests performed on the extraction of features (buildings and roads) from real high-resolution satellite images have been performed and results are shown here. Finally, to complete the data acquisition process, the use of GPS-GIS data-logger receivers in differential mode is proposed

Recognition of landslides in lunar impact craters

Landslides have been observed on several planets and minor bodies of the solar System, including the Moon. Notwithstanding different types of slope failures have been studied on the Moon, a detailed lunar landslide inventory is still pending. Undoubtedly, such will be in a benefit for future geological and morphological studies, as well in hazard, risk and suscept- ibility assessments. A preliminary survey of lunar landslides in impact craters has been done using visual inspection on images and digital elevation model (DEM) (Brunetti et al. 2015) but this method suffers from subjective interpretation. A new methodology based on polynomial interpolation of crater cross-sections extracted from global lunar DEMs is presented in this paper. Because of their properties, Chebyshev polynomials were already exploited for para- metric classification of different crater morphologies (Mahanti et al., 2014). Here, their use has been extended to the discrimination of slumps in simple impact craters. Two criteria for recognition have provided the best results: one based on fixing an empirical absolute thresholding and a second based on statistical adaptive thresholding. The application of both criteria to a data set made up of 204 lunar craters’ cross-sections has demonstrated that the former criterion provides the best recognition

Localizzazione e caratterizzazione di frane all’interno dei crateri di impatto lunari

Geological slope failure processes have been observed on the Moon surface for decades. However a detailed and exhaustive lunar landslide inventory has not been produced yet. As a part of the “Moon Mapping” cooperative project between Italy and China, an algorithm for lunar landslide detection in impact craters has been proposed. The simple type of impact craters sizing between 5-12 km has been analysed. The Chebyshev polynomials have been used for estimating crater’s cross-sectional profiles on the basis of a 100 m x 100 m resolution digital elevation model (WACGDL100 DEM) derived from LROC NASA mission. The presence of landslides in lunar craters is then investigated by analysing the contribution of odd coefficients of the estimated polynomials, since they are representing the asymmetric component of a transversal profile. After the analysis of four orthogonal profiles per crater, we correctly classified 87.7% of cross-sectional profiles really affected by slope failures. On the other side, we obtained a correct classification of 83.3% of cross- sectional profiles without slope failures. Even though a complete successful rate could not be achieved, these results are quite encouraging since the proposed automated procedure would allow to a first scrutiny of the presence of landslides in craters, to be refined afterwards with visual recognition and the analysis of other types of data

Spatiotemporal Pattern Detection of Ground Deformations Induced by Extreme Rainfall using InSAR EGMS: The case of Cortina d’Ampezzo after Vaia Storm

During October 2018 Vaia Storm occurred in the north of Italy, resulting in a huge amount of rainfall that was recorded. The focus here is given to Cortina d'Ampezzo area in the Veneto Region, due to the high importance of the area from touristic and sport perspectives and the presence of landslides. This study is devoted to investigating the impact of the severe sudden rainfall caused by this extreme atmospheric disturbance on the trends of ground deformations over this area, adopting a risk assessment perspective. The ground deformation Time Series (TS) have been derived from the European Ground Motion Service (EGMS) Ortho products derived from Sentinel-1 InSAR data. Then, according to the daily precipitation records and considering the time of this event as a turning temporal point, the TSs of all data points have been divided into pre-event and post-event phases. After obtaining the displacement rates in each phase, the quantified magnitude of changes in the pre-post rates has been calculated through a proposed simple formulation. The spatial distribution of the deformation parameters (i.e., pre-event displacement velocity and change in the pre-post displacement velocities) is found to be a practical tool for gaining comprehensive knowledge regarding the ground deformation and the effect of the extreme weather conditions on the displacement trends over the area. Furthermore, the positioning of the occurrence of deformation parameters has been compared to the landslide inventory of the area. The results showed that the extreme rainfall caused severe acceleration of displacements, more significant in horizontal East-West direction rather than vertical Up-Down direction. Some slight deceleration has been also detected. No initiation (or reactivation) of the stable zones was witnessed, and the portions with high magnitude of pre-event velocities are the ones whose displacement rates have been remarkably modified due to the severe event