Open source tool for DSMs generation from high resolution optical satellite imagery. Development and testing of an OSSIM plug-in

The fully automatic generation of digital surface models (DSMs) is still an open research issue. From recent years, computer vision algorithms have been introduced in photogrammetry in order to exploit their capabilities and efficiency in three-dimensional modelling. In this article, a new tool for fully automatic DSMs generation from high resolution satellite optical imagery is presented. In particular, a new iterative approach in order to obtain the quasi-epipolar images from the original stereopairs has been defined and deployed. This approach is implemented in a new Free and Open Source Software (FOSS) named Digital Automatic Terrain Extractor (DATE) developed at the Geodesy and Geomatics Division, University of Rome ‘La Sapienza’, and conceived as an Open Source Software Image Map (OSSIM) plug-in. DATE key features include: the epipolarity achievement in the object space, thanks to the images ground projection (Ground quasi-Epipolar Imagery (GrEI)) and the coarse-to-fine pyramidal scheme adopted; the use of computer vision algorithms in order to improve the processing efficiency and make the DSMs generation process fully automatic; the free and open source aspect of the developed code. The implemented plug-in was validated through two optical datasets, GeoEye-1 and the newest Pléiades-high resolution (HR) imagery, on Trento (Northern Italy) test site. The DSMs, generated on the basis of the metadata rational polynomial coefficients only, without any ground control point, are compared to a reference lidar in areas with different land use/land cover and morphology. The results obtained thanks to the developed workflow are good in terms of statistical parameters (root mean square error around 5 m for GeoEye-1 and around 4 m for Pléiades-HR imagery) and comparable with the results obtained through different software by other authors on the same test site, whereas in terms of efficiency DATE outperforms most of the available commercial software. These first achievements indicate good potential for the developed plug-in, which in a very near future will be also upgraded for synthetic aperture radar and tri-stereo optical imagery processing

FOSS4G date assessment on the isprs optical stereo satellite data. A benchmark for DSM generation

The ISPRS Working Group 4 Commission I on "Geometric and Radiometric Modelling of Optical Spaceborne Sensors", provides a benchmark dataset with several stereo data sets from space borne stereo sensors. In this work, the Worldview-1 and Cartosat-1 datasets are used, in order to test the Free and Open Source Software for Geospatial (FOSS4G) Digital Automatic Terrain Extractor (DATE), developed at Geodesy and Geomatics Division, University of Rome "La Sapienza", able to generate Digital Surface Models starting from optical and SAR satellite images. The accuracy in terms of NMAD ranges from 1 to 3 m for Wordview-1, and from 4 to 6 m for Cartosat-1. The results obtained show a general better 3D reconstruction for Worldview-1 DSMs with respect to Cartosat-1, and a different completeness level for the three analysed tiles, characterized by different slopes and land cover

A Riemann-Hilbert formulation for the finite temperature Hubbard model

Inspired by recent results in the context of AdS/CFT integrability, we reconsider the Thermodynamic Bethe Ansatz equations describing the 1D fermionic Hubbard model at finite temperature. We prove that the infinite set of TBA equations are equivalent to a simple nonlinear Riemann-Hilbert problem for a finite number of unknown functions. The latter can be transformed into a set of three coupled nonlinear integral equations defined over a finite support, which can be easily solved numerically. We discuss the emergence of an exact Bethe Ansatz and the link between the TBA approach and the results by J\"uttner, Kl\"umper and Suzuki based on the Quantum Transfer Matrix method. We also comment on the analytic continuation mechanism leading to excited states and on the mirror equations describing the finite-size Hubbard model with twisted boundary conditions.Comment: 43 pages, 13 figures. v2: References added, typos corrected, minor changes to the text. v3: JHEP published version; typos corrected, references added and text improved in Section

Odors, words and objects

The paper focuses on concepts and words referring to odors and to objects that have an odor. We argue that odors are an interesting object of study since they are evanescent, and since odor words do not refer to concrete and manipulable objects, but to scents evoked by objects. A second reason why odors are interesting is that some languages, as the Western ones, lack a specific odor lexicon, comparable in richness and variety to the color lexicon, and that performance on odors naming is typically worse than performance in color naming. In this work we discuss three main issues. First, we illustrate literature showing that, even if odor words do not have concrete referents, many languages encode them quite easily: the case of odors suggests that word meaning cannot be exhausted by the relationship with a referent, and highlights the importance of the social sharing of meaning. Second, we have discussed the peculiar status of odor concepts and words. Given their ambiguous status, their simple existence poses problems both to theories according to which concrete and abstract concepts do not differ, and to theories according to which they represent a dichotomy. Finally, we present an experiment in which we show that names of objects evoke their smell, and that these smells evoke approach and avoidance movements, in line with theories according to which words are grounded in both sensorial and motor systems

Using Virtual Environments as a Visual Interface for Accessing Cultural Database Contents

Cultural institutions have to deal with an enormous amount of data, which are stored in cultural databases usually designed for and managed by professionals. Difficulties in accessing such databases usually preclude or limit their use for the general public. Moreover, in the historic, artistic and cultural areas, an important part of the information associated to an object is related to its original historical and spatial context, an evidence that is often not disclosed, or is difficult to explain, to the non experts. For this reason, it is important to try to re-contextualize - where possible - the elements of cultural collections in the places where these objects were in the past. To this end, in this work we propose the integration of databases and Virtual Reality technologies to develop novel visual interfaces to improve the accessibility, for the non experts, to the contents of cultural databases. Virtual Reality is used to re-create the contextual environment of the objects in the database, which can be explored to gain new insights on specific elements and to improve the awareness of relationships between them. The use of two different types of Virtual Environments has been investigated in the development of the proposed visual interfaces. Results of their evaluation by a user panel, in order to assess the accessibility and effectiveness of both interfaces in relation to each other and with a classic text-based interface, are also presente

An objective assessment to investigate the impact of turning angle on freezing of gait in Parkinson's disease

Freezing of gait (FoG) is often described in subjects with Parkinson's disease (PD) as a sudden inability to continue the forward walking progression. FoG occurs most often during turning, especially at sharp angles. Here, we investigated 180 and 360 degrees turns in two groups: PD subjects reporting FoG (FoG+), and PD subjects without FoG (FoG-). Forty-three subjects (25 FoG+, 18 FoG-) wore an inertial sensor on their back while walking back and forth continuously for 2 min (reversing direction with a 180° turn), and while turning in place for 1 min (alternating 360° turning in opposite directions). Objective measures (turn duration, peak velocity, jerkiness and range of acceleration) were computed during the turns and compared across FoG+ and FoG-groups. Results showed that FoG+ compared to FoG-took significantly a longer time to complete 360° turns than 180° turns. A significant lower turn peak velocity, higher jerkiness and an increased range of medio-lateral acceleration was also found in FoG+. Significant differences between the two groups across the two turning tasks validated the hypothesis that sharper turns might cause higher instability in FoG+ compared to FoG-

Balancing work and family in Italy: New mothersÂ’ employment decisions after childbirth

Compared with other European countries, the Italian labour market stands out for the low level of both female participation and fertility. In this paper we focus on the employment patterns of Italian mothers around the time of childbirth. Our hypothesis is that the difficulties involved in reconciling work and family when there are children are among the leading causes of the low female employment rate in Italy. Data from the 2002 Italian Birth Sample Survey show that about 20 per cent of mothers who were working before childbirth, stop working one and a half years after delivery and that about 14 per cent voluntarily decide to resign. The paper analyses the factors that most influence new mothersÂ’ unemployment risk after childbirth.female employment, childbirth, childcare