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Publicações

Publicações por CRIIS

2018

Pixel-Based Leaf Segmentation from Natural Vineyard Images Using Color Model and Threshold Techniques

Autores
Pereira, CS; Morais, R; Reis, MJCS;

Publicação
IMAGE ANALYSIS AND RECOGNITION (ICIAR 2018)

Abstract
The presence in natural vineyard images of savage foliage, weed, multiple leaves with overlapping, occlusion, and obstruction by objects due to the shadows, dust, insects and other adverse climatic conditions that occur in natural environment at the moment of image capturing, turns leaf segmentation a challenging task. In this paper, we propose a segmentation algorithm based on region growing using color model and threshold techniques for classification of the pixels belonging to vine leaves from vineyard color images captured in real field environment. To assess the accuracy of the proposed vine leaf segmentation algorithm, a supervised evaluation method was employed, in which a segmented image is compared against a manually-segmented one. Concerning boundary-based measures of quality, an average accuracy of 94.8% over a 140 image dataset was achieved. It proves that the proposed method gives suitable results for an ongoing research work for automatic identification and characterization of different endogenous grape varieties of the Portuguese Douro Demarcated Region.

2018

Multi-Temporal Analysis of Forestry and Coastal Environments Using UASs

Autores
Padua, L; Hruska, J; Bessa, J; Adao, T; Martins, LM; Goncalves, JA; Peres, E; Sousa, AMR; Castro, JP; Sousa, JJ;

Publicação
REMOTE SENSING

Abstract
Due to strong improvements and developments achieved in the last decade, it is clear that applied research using remote sensing technology such as unmanned aerial vehicles (UAVs) can provide a flexible, efficient, non-destructive, and non-invasive means of acquiring geoscientific data, especially aerial imagery. Simultaneously, there has been an exponential increase in the development of sensors and instruments that can be installed in UAV platforms. By combining the aforementioned factors, unmanned aerial system (UAS) setups composed of UAVs, sensors, and ground control stations, have been increasingly used for remote sensing applications, with growing potential and abilities. This paper's overall goal is to identify advantages and challenges related to the use of UAVs for aerial imagery acquisition in forestry and coastal environments for preservation/prevention contexts. Moreover, the importance of monitoring these environments over time will be demonstrated. To achieve these goals, two case studies using UASs were conducted. The first focuses on phytosanitary problem detection and monitoring of chestnut tree health (Padrela region, Valpacos, Portugal). The acquired high-resolution imagery allowed for the identification of tree canopy cover decline by means of multi-temporal analysis. The second case study enabled the rigorous and non-evasive registry process of topographic changes that occurred in the sandspit of Cabedelo (Douro estuary, Porto, Portugal) in different time periods. The obtained results allow us to conclude that the UAS constitutes a low-cost, rigorous, and fairly autonomous form of remote sensing technology, capable of covering large geographical areas and acquiring high precision data to aid decision support systems in forestry preservation and coastal monitoring applications. Its swift evolution makes it a potential big player in remote sensing technologies today and in the near future.

2018

Quantification of Ethanol Concentration in Gasoline Using Cuprous Oxide Coated Long Period Fiber Gratings

Autores
Monteiro Silva, F; Santos, JL; Marques Martins de Almeida, JMMM; Coelho, L;

Publicação
IEEE SENSORS JOURNAL

Abstract
It is reported a new optical sensing system, based on long period fiber gratings (LPFGs) coated with cuprous oxide (Cu2O), for the quantification of ethanol concentration in ethanol-gasoline mixtures. The detection principle is based on the spectral features dependence of the Cu2O coated LPFGs on the refractive index of the surrounding medium. The chemical constitution of the ethanol-gasoline samples was obtained by gas chromatography mass spectrometry (GC) and GC thermal conductivity detection. Two different modes of operation are presented, wavelength shift and optical power shift mode of operation, with good linear relations between ethanol concentration and the corresponding spectral features of the LPFGs, R-2 = 0.999 and 0.996, respectively. In the range of ethanol concentration up to 30% v/v, the sensitivities were 0.76 +/- 0.01 nm/% v/v and 0.125 +/- 0.003 dB/% v/v with resolutions of 0.21% v/v and 0.73% v/v and limits of detection of 1.63% v/v and 2.10% v/v, for the for the same operation modes, respectively.

2018

Unmanned Aerial Systems (UAS) for environmental applications special issue preface PREFACE

Autores
Milas, AS; Sousa, JJ; Warner, TA; Teodoro, AC; Peres, E; Goncalves, JA; Delgado Garcia, J; Bento, R; Phinn, S; Woodget, A;

Publicação
INTERNATIONAL JOURNAL OF REMOTE SENSING

Abstract

2018

A rapid prototyping tool to produce 360° video-based immersive experiences enhanced with virtual/multimedia elements

Autores
Adao, T; Pádua, L; Fonseca, M; Agrellos, L; Sousa, JJ; Magalhaes, L; Peres, E;

Publicação
CENTERIS 2018 - INTERNATIONAL CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS / PROJMAN 2018 - INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT / HCIST 2018 - INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES, CENTERI

Abstract
While the popularity of virtual reality (VR) grows in a wide range of application contexts - e.g. entertainment, training, cultural heritage and medicine -, its economic impact is expected to reach around 15bn USD, by the year of 2020. Within VR field, 360video has been sparking the interest of development and research communities. However, editing tools supporting 360panoramas are usually expensive and/or demand programming skills and/or advanced user knowledge. Besides, application approaches to quickly and intuitively set up such 360video-based VR environments complemented with diverse types of parameterizable virtual assets and multimedia elements are still hard to find. Thereby, this paper aims to propose a system specification to simply and rapidly configure immersive VR environments composed of surrounding 360video spheres that can be complemented with parameterizable multimedia contents - namely 3D models, text and spatial sound -, whose behavior can be either time-range or user-interaction dependent. Moreover, a preliminary prototype that follows a substantial part of the previously mentioned specification and implements the enhancement of 360videos with time-range dependent virtual assets is presented. Preliminary tests evaluating usability and user satisfaction were also carried out with 30 participants, from which encouraging results were achieved.

2018

Potential of synthetic chalcone derivatives to prevent marine biofouling

Autores
Almeida, JR; Moreira, J; Pereira, D; Pereira, S; Antunes, J; Palmeira, A; Vasconcelos, V; Pinto, M; Correia da Silva, M; Cidade, H;

Publicação
SCIENCE OF THE TOTAL ENVIRONMENT

Abstract
Biofouling represents a major economic, environmental and health concern for which new eco-friendly solutions are needed. International legislation has restricted the use of biocidal-based antifouling coatings, and increasing efforts have been applied in the search for environmentally friendly antifouling agents. This research work deals with the assessment of the interest of a series of synthetic chalcone derivatives for antifouling applications. Sixteen chalcone derivatives were synthesized with moderate yields (38-85%). Antifouling bioactivity of these compounds was assessed at different levels of biological organization using both anti-macrofouling and anti-microfouling bioassays, namely an anti-settlement assay using mussel (Mytilus galloprovincialis) larvae, as well as marine bacteria and microalgal biofilms growth inhibition bioassays. Results showed that three compounds (11, 12, and 16) were particularly active against the settlement of mussel larvae (EC50 7.24-34.63 mu M), being compounds 12 and 16 also able to inhibit the growth of microfouling species (EC50 4.09-20.31 mu M). Moreover, the most potent compounds 12 and 16 were found to be non-toxic to the non-target species Artemia salina (<10% mortality at 25 mu M). A quantitative structure-activity relationship model predicted that descriptors describing the ability of molecules to form hydrogen bonds and encoding the shape, branching ratio and constitutional diversity of the molecule were implied in the antifouling activity against the settlement of mussel larvae. This work elucidates for the first time the relevance of synthesizing chalcone derivatives to generate new nontoxic products to prevent marine biofouling.

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