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2019

UAV-Based Automatic Detection and Monitoring of Chestnut Trees

Authors
Marques, P; Padua, L; Adao, T; Hruska, J; Peres, E; Sousa, A; Sousa, JJ;

Publication
Remote Sensing

Abstract
Unmanned aerial vehicles have become a popular remote sensing platform for agricultural applications, with an emphasis on crop monitoring. Although there are several methods to detect vegetation through aerial imagery, these remain dependent of manual extraction of vegetation parameters. This article presents an automatic method that allows for individual tree detection and multi-temporal analysis, which is crucial in the detection of missing and new trees and monitoring their health conditions over time. The proposed method is based on the computation of vegetation indices (VIs), while using visible (RGB) and near-infrared (NIR) domain combination bands combined with the canopy height model. An overall segmentation accuracy above 95% was reached, even when RGB-based VIs were used. The proposed method is divided in three major steps: (1) segmentation and first clustering; (2) cluster isolation; and (3) feature extraction. This approach was applied to several chestnut plantations and some parameters—such as the number of trees present in a plantation (accuracy above 97%), the canopy coverage (93% to 99% accuracy), the tree height (RMSE of 0.33 m and R2 = 0.86), and the crown diameter (RMSE of 0.44 m and R2 = 0.96)—were automatically extracted. Therefore, by enabling the substitution of time-consuming and costly field campaigns, the proposed method represents a good contribution in managing chestnut plantations in a quicker and more sustainable way.

2019

mySense: A comprehensive data management environment to improve precision agriculture practices

Authors
Morais, R; Silva, N; Mendes, J; Adao, T; Padua, L; Lopez Riquelme, J; Pavon Pulido, N; Sousa, JJ; Peres, E;

Publication
Computers and Electronics in Agriculture

Abstract

2019

Procedural Modeling of Buildings Composed of Arbitrarily-Shaped Floor-Plans: Background, Progress, Contributions and Challenges of a Methodology Oriented to Cultural Heritage

Authors
Adao, T; Padua, L; Marques, P; Sousa, JJ; Peres, E; Magalhaes, L;

Publication
Computers

Abstract
Virtual models' production is of high pertinence in research and business fields such as architecture, archeology, or video games, whose requirements might range between expeditious virtual building generation for extensively populating computer-based synthesized environments and hypothesis testing through digital reconstructions. There are some known approaches to achieve the production/reconstruction of virtual models, namely digital settlements and buildings. Manual modeling requires highly-skilled manpower and a considerable amount of time to achieve the desired digital contents, in a process composed by many stages that are typically repeated over time. Both image-based and range scanning approaches are more suitable for digital preservation of well-conserved structures. However, they usually require trained human resources to prepare field operations and manipulate expensive equipment (e.g., 3D scanners) and advanced software tools (e.g., photogrammetric applications). To tackle the issues presented by previous approaches, a class of cost-effective, efficient, and scarce-data-tolerant techniques/methods, known as procedural modeling, has been developed aiming at the semi- or fully-automatic production of virtual environments composed of hollow buildings exclusively represented by outer façades or traversable buildings with interiors, either for expeditious generation or reconstruction. Despite the many achievements of the existing procedural modeling approaches, the production of virtual buildings with both interiors and exteriors composed by non-rectangular shapes (convex or concave n-gons) at the floor-plan level is still seldomly addressed. Therefore, a methodology (and respective system) capable of semi-automatically producing ontology-based traversable buildings composed of arbitrarily-shaped floor-plans has been proposed and continuously developed, and is under analysis in this paper, along with its contributions towards the accomplishment of other virtual reality (VR) and augmented reality (AR) projects/works oriented to digital applications for cultural heritage. Recent roof production-related enhancements resorting to the well-established straight skeleton approach are also addressed, as well as forthcoming challenges. The aim is to consolidate this procedural modeling methodology as a valuable computer graphics work and discuss its future~directions.

2019

Classification of an Agrosilvopastoral System Using RGB Imagery from an Unmanned Aerial Vehicle

Authors
Pádua, L; Guimarães, N; Adão, T; Marques, P; Peres, E; Sousa, A; Sousa, JJ;

Publication
Progress in Artificial Intelligence - Lecture Notes in Computer Science

Abstract

2019

Digital Ampelographer: A CNN Based Preliminary Approach

Authors
Adão, T; Pinho, TM; Ferreira, A; Sousa, A; Pádua, L; Sousa, J; Sousa, JJ; Peres, E; Morais, R;

Publication
Progress in Artificial Intelligence - Lecture Notes in Computer Science

Abstract