Javier Bonatti

UBRISTES: UAV-Based Building Rehabilitation with Visible and Thermal Infrared Remote Sensing

Building inspection is a critical issue for designing rehabilitation projects, which are recently gaining importance for environmental and energy efficiency reasons. Image sensors on-board unmanned aerial vehicles are a powerful tool for building inspection, given the diversity and complexity of facades and materials, and mainly, their vertical disposition. The UBRISTES (UAV-based Building Rehabilitation with vISible and ThErmal infrared remote Sensing) system is proposed as an effective solution for facade inspection in urban areas, validating a method for the simultaneous acquisition of visible and thermal aerial imaging applied to the detection of the main types of facade anomalies/pathologies, and showcasing its possibilities using a first principles analysis. Two public buildings have been considered for evaluating the proposed system. UBRISTES is ready to use in building inspection and has been proved as a useful tool in the design of rehabilitation projects for inaccessible, complex building structures in the context of energy efficiency.

An Operational Framework for Land Cover Classification in the Context of REDD+ Mechanisms. A Case Study from Costa Rica

REDD+ implementation requires robust, consistent, accurate and transparent national land cover historical data and monitoring systems. Satellite imagery is the only data source with enough periodicity to provide consistent land cover information in a cost-effective way. The main aim of this paper is the creation of an operational framework for monitoring land cover dynamics based on Landsat imagery and open-source software. The methodology integrates the entire land cover and land cover change mapping processes to produce a consistent series of Land Cover maps. The consistency of the time series is achieved through the application of a single trained machine learning algorithm to radiometrically normalized imagery using iteratively re-weighted multivariate alteration detection (IR-MAD) across all dates of the historical period. As a result, seven individual Land Cover maps of Costa Rica were produced from 1985/1986 to 2013/2014. Post-classification land cover change detection was performed to evaluate the land cover dynamics in Costa Rica. The validation of the land cover maps showed an overall accuracy of 87% for the 2013/2014 map, 93% for the 2000/2001 map and 89% for the 1985/1986 map. Land cover changes between forest and non-forest classes were validated for the period between 2001 and 2011, obtaining an overall accuracy of 86%. Forest age-classes were generated through a multi-temporal analysis of the maps. By linking deforestation dynamics with forest age, a more accurate discussion of the carbon emissions along the time series can be presented.

Anomaly detection using remote sensing for the archaeological heritage registration

The aim of this work is an approach using multisensor remote sensing techniques to recognize the potential remains and recreate the original landscape of three archaeological sites. We investigate the spectral characteristics of the reflectance parameter and emissivity in the pattern recognition of archaeological materials in several hyperspectral scenes of the prehispanic site in Palmar Sur (Costa Rica), the Jarama Valley site and the celtiberian city of Segeda in Spain. Spectral ranges of the visible-near infrared (VNIR), shortwave infrared (SWIR) and thermal infrared (TIR) from hyperspectral data cubes of HyMAP, AHS, MASTER and ATM have been used. Several experiments on natural scenarios of Costa Rica and Spain of different complexity, have been designed. Spectral patterns and thermal anomalies have been calculated as evidences of buried remains and change detection. First results, land cover change analyses and their consequences in the digital heritage registration are discussed.

Spectral Analysis for Anomaly Detection in the Central Volcanic Range, Costa Rica. Implications for Planetary Geology

The aim of this work is to study the IR spectra (reflectance and absorbance) of samples from the Central Volcanic Range (CVR) of Costa Rica and their relationship as outliers in anomaly detection. We investigate the spectral characteristics of variable reflectance in the pattern recognition of geological materials in several single hyperspectral scenes. It is assumed no prior knowledge of the targets in anomaly detection. Thus, the pixels are automatically separated according to their spectral information, significantly differentiated with respect to a background, either globally for the full scene, or locally by the image segmentation. Spectral ranges of the visible-near infrared (VNIR), shortwave infrared (SWIR) and thermal infrared (TIR) from hyperspectral data cubes of HyMAP and MASTER have been used. Several experiments on natural scenarios of the CVR and semi-urban of different complexity, have been designed, analyzing the behavior of the standard RX anomaly detector and different approaches based on image projection and dimensionality reduction. First results and their consequences as terrestrial analogs in planetary exploration are discussed.

Remarks on the one-photon-pair annihilation in strong magnetic fields

We report specifically on a quantum electrodynamic feature of the one-photon-pair annihilation. Most of the calculation related with this process (not excluding other ones) have been carried out usually utilizing the wave functions obtained from the Dirac equation in the Landau gauge Aα = (0,Bx, 0), where B is oriented along the z-axis (Johnson and Lippman, 1949). Although, the eigenstates of the Dirac Hamiltonian as it was introduced by Johnson and Lippman, do not consider the coupling to the radiation field and consequently they reflect only forpz = 0 the same linear combination of the two degenerate polarization states.We report the transition rate function for the one-photon-pair annihilation in a strong magnetic field by using the Sokolov and Ternov eigenstate |±〉 as far aspz = 0 andN > 0 is concerned. The difference between the expression for the transition rate by using the Sokolov and Ternov eigenstates and the one calculated by (Wunneret al., 1986), is just the functionIs,s′ which corresponds to the degeneracy of the orbit center of the electrons characterized by the quantum numberss ands′.

On the natural line width of absorption lines in strong magnetic stellar fields

In the last years, the interest in explaining the existence of a singularity at low frequencies (ω = 0) in the differential cross section of photon scattering by electrons, in a homogeneous magnetic field, for the transitions between the Landau levelsN = 1 andN′ = 0, has greatly increased. It is the purpose of this paper to present a calculation of the cross section for the absorption of radiation by an electron in a strong magnetic stellar field, using the Wigner-Weisskopf approximation to better understand this kind of singularity in the Compton cross section.

Magnetic absorption lines in stellar spectra

AbstractWe analyze the process of absorption which is produced under conditions of strong magnetic fields in the magnetosphere of a compact stellar source. The magnitude of the magnetic field lies in the range 1012-1013 Gauss, which are common values in modelling pulsars.Analyzing the first absorption lines (N = 0 toN′ ≤ 3) we arrive to the conclusions that the orientation of electrons spin does not change if it absorbs a photon. It means it maintains its orientation opposite to the external magnetic field after the absorption. For the fundamental line (N = 0 toN′ = 1) the dominant polarization of the photon is. For the next two transition lines (N = 0 toN′ = 2 andN = 0 toN′ = 3), the polarization is. In the case that the absorption lines belong to one of the first three transition lines, then the mean photon energy can be approached with the relation

Land cover dynamics in Osa Region, Costa Rica: secondary forest is here to stay

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