Search results for "Radar"
showing 10 items of 248 documents
A hybrid multi-criteria approach to GPR image mining applied to water supply system maintenance
2018
[EN] Data processing techniques for Ground Penetrating Radar (GPR) image mining provide essential information to optimize maintenance management of Water Supply Systems (WSSs). These techniques aim to elaborate on radargrams in order to produce meaningful graphical representations of critical buried components of WSSs. These representations are helpful non-destructive evaluation tools to prevent possible failures in WSSs by keeping them adequately monitored. This paper proposes an integrated multi-criteria decision making (MCDM) approach to prioritize various data processing techniques by means of ranking their outputs, namely their resulting GPR image representations. The Fuzzy Analytic Hi…
Machine learning in remote sensing data processing
2009
Remote sensing data processing deals with real-life applications with great societal values. For instance urban monitoring, fire detection or flood prediction from remotely sensed multispectral or radar images have a great impact on economical and environmental issues. To treat efficiently the acquired data and provide accurate products, remote sensing has evolved into a multidisciplinary field, where machine learning and signal processing algorithms play an important role nowadays. This paper serves as a survey of methods and applications, and reviews the latest methodological advances in machine learning for remote sensing data analysis.
Electromagnetic and ultrasonic investigations on a Roman marble slab
2011
The archaeological museum of Rome asked our group about the physical consistency of a marble slab (second to third century AD) that recently fell during its travel as part of an exhibition. We decided to use different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate the internal coupling pins, and ground-penetrating radar (GPR) (2000 MHz) and ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the hidden ones. For the ultrasonic data, tests were carried out to optimize the inversion parameters, in particular the cell dimensions. Surely, the choice of cell size …
Multispectral integral imaging acquisition and processing using a monochrome camera and a liquid crystal tunable filter
2012
This paper presents an acquisition system and a procedure to capture 3D scenes in different spectral bands. The acquisition system is formed by a monochrome camera, and a Liquid Crystal Tunable Filter (LCTF) that allows to acquire images at different spectral bands in the [480, 680]nm wavelength interval. The Synthetic Aperture Integral Imaging acquisition technique is used to obtain the elemental images for each wavelength. These elemental images are used to computationally obtain the reconstruction planes of the 3D scene at different depth planes. The 3D profile of the acquired scene is also obtained using a minimization of the variance of the contribution of the elemental images at each …
Quaderno di Diagnostica. Le indagini diagnostiche nel restauro dei monumenti
2010
Negli ultimi anni il crescente interesse per il costruito urbano e la maturazione di una sensibilità maggiore nei confronti dell'autenticità materiale delle architetture hanno supportato lo sviluppo dell'imponente settore sperimentale della diagnostica, che comprende le indagini preliminari, quelle in corso d'opera (diagnostica interventistica) e le verifiche della qualità degli interventi svolti. Lo sviluppo delle metodologie analitiche diagnostiche, in particolare delle scienze fisiche, chimiche, geognostiche e dei metodi informatici di calcolo, offre oggi ai restauratori una ricca serie di strumenti di previsione, di progettazione dei trattamenti da trasporre nella prassi operativa e di …
Superresolved Holographic Microscopy
2008
Superresolution methods in digital holographic microscopy provide a useful tool to overcome the Abbe's diffraction limit when using modest microscope lenses. The process improves the cutoff frequency of the microscope lens by means of the generation of a synthetic aperture based on time multiplexing and using 3 main stages: optical coding, optical decoding, and digital postprocessing. After the whole process, a superresolved image is obtained by Fourier transformation of the synthetic aperture.
Superesolution in digital holographic microscopy
2011
In this contribution, we address with the possibility to overcome the limited resolving power of imaging systems beyond the limit imposed by Abbe's diffraction theory. We first review the mathematical foundations underlying superresolution (SR) from an information theory point of view and then we focus on two multiplexing approaches in digital holographic microscopy (DHM) for achieving SR by synthetic aperture (SA) generation.
Synthetic Aperture Lensless Digital Holographic Microscopy (SALDHM) for Superresolved Biological Imaging
2013
Lensless digital holographic microscopy (LDHM) relates with the capability to achieve microscopic imaging working without lenses in the regime of holography. LDHM uses an extremely simplified setup and provides micron-range lateral and depth resolutions in three-dimensional (3D) imaging. Typically, LDHM uses a pinhole to provide spherical divergent illumination over the sample. Then, two different basic schemes are usually adopted for providing holographic recording. The first one assumes the interference between two in-line waves since diffraction by the sample can be considered as a perturbation of the reference wave. The second scheme uses an external reference beam in an off-line config…
Superresolved phase-shifting Gabor holography by CCD shift
2009
Holography in the Gabor regime is restricted to weak diffraction assumptions. Otherwise, diffraction prevents an accurate recovery of the object's complex wavefront. We have recently proposed a modified Gabor-like setup to extend Gabor's concept to any sample provided that it be non-diffusive. However, the resolution of the final image becomes limited as a consequence of the additional elements considered in the proposed setup. In this paper we present an experimental approach to overcome such a limitation in which the former configuration is used while the CCD camera is shifted to different off-axis positions in order to generate a synthetic aperture. Thus, once the whole image set is reco…
ETP/GDOP Behavior Study for N-Sensors Arrays ina Multilateration Radar System
2009
In this paper, we evaluated the ETP (Expected Theoretical Precision) and GDOP (Geometric Dilution Of Precision) enhancement related to the number of sensors in a Multilateration radar system. An introduction about the principles of the Multilateration radar system basis operation is described, then, the formulation for evaluation the ETP/GDOP of the 3D positioning is shown. We observed that the ETP and GDOP enhance with the increase of the number of sensors. A substantial improvement was obtained until nine sensors but, for more sensors that improvement is reduced. Results for a 75km×75km area are shown, including LAM (Local Area Multilateration) and WAM (Wide Area Multilateration) settings…