Hybrid Overlap Filter for LiDAR Point Clouds Using Free Software

[EN] Despite the large amounts of resources destined to developing filtering algorithms of LiDAR point clouds in order to obtain a Digital Terrain Model (DTM), the task remains a challenge. As a society advancing towards the democratization of information and collaborative processes, the researchers should not only focus on improving the efficacy of filters, but should also consider the users' needs with a view toward improving the usability and accessibility of the filters in order to develop tools that will provide solutions to the challenges facing this field of study. In this work, we describe the Hybrid Overlap Filter (HyOF), a new filtering algorithm implemented in the free R software environment. The flow diagram of HyOF differs in the following ways from that of other filters developed to date: (1) the algorithm is formed by a combination of sequentially operating functions (i.e., the output of the first function provides the input of the second), which are capable of functioning independently and thus enabling integration of these functions with other filtering algorithms; (2) the variable penetrability is defined and used, along with slope and elevation, to identify ground points; (3) prior to selection of the seed points, the original point cloud is processed with the aim of removing points corresponding to buildings; and (4) a new method based on a moving window, with longitudinal overlap between windows and transverse overlap between passes, is used to select the seed points. Our hybrid filtering method is tested using 15 reference samples acquired by the International Society of Photogrammetry and Remote Sensing (ISPRS) and is evaluated in comparison with 33 existing filtering algorithms. The results show that our hybrid filtering method produces an average total error of 3.34% and an average Kappa coefficient of 92.62%. The proposed algorithm is one of the most accurate filters that has been tested with the ISPRS reference samplesSIThis research was funded by the Project Red de Tecnoloxías LiDAR e de Información Xeoespacial (Plan Galego 2011–2015 (Plan I2C): Programa Consolidación e Estructuración (Redes)-CN 2012/323

Hybrid Overlap Filter for LiDAR Point Clouds Using Free Software

Despite the large amounts of resources destined to developing filtering algorithms of LiDAR point clouds in order to obtain a Digital Terrain Model (DTM), the task remains a challenge. As a society advancing towards the democratization of information and collaborative processes, the researchers should not only focus on improving the efficacy of filters, but should also consider the users’ needs with a view toward improving the usability and accessibility of the filters in order to develop tools that will provide solutions to the challenges facing this field of study. In this work, we describe the Hybrid Overlap Filter (HyOF), a new filtering algorithm implemented in the free R software environment. The flow diagram of HyOF differs in the following ways from that of other filters developed to date: (1) the algorithm is formed by a combination of sequentially operating functions (i.e., the output of the first function provides the input of the second), which are capable of functioning independently and thus enabling integration of these functions with other filtering algorithms; (2) the variable penetrability is defined and used, along with slope and elevation, to identify ground points; (3) prior to selection of the seed points, the original point cloud is processed with the aim of removing points corresponding to buildings; and (4) a new method based on a moving window, with longitudinal overlap between windows and transverse overlap between passes, is used to select the seed points. Our hybrid filtering method is tested using 15 reference samples acquired by the International Society of Photogrammetry and Remote Sensing (ISPRS) and is evaluated in comparison with 33 existing filtering algorithms. The results show that our hybrid filtering method produces an average total error of 3.34% and an average Kappa coefficient of 92.62%. The proposed algorithm is one of the most accurate filters that has been tested with the ISPRS reference samplesThis research was funded by the Project Red de Tecnoloxías LiDAR e de Información Xeoespacial (Plan Galego 2011–2015 (Plan I2C): Programa Consolidación e Estructuración (Redes)-CN 2012/323)S

MARLI: a mobile application for regional landslide inventories in Ecuador

[EN] The regions of Central and South America most susceptible to the occurrence of landslides will become even more vulnerable in the context of climate change. The Josefina disaster, in 1993, demonstrated both the vulnerability of local infrastructures and communities in the Paute River basin (Ecuador). Since this natural phenomena, several landslide inventories and susceptibility studies were developed, revealing the vulnerability of the Paute River basin to unstable terrain and the need for further studies throughout the basin. Despite this, no studies have been done since then to update the information generated. This paper describes a Mobile Application for Regional Landslide Inventories (MARLI), a simple but efficient open-access platform to report landslide events using the Open Data Kit system. Its design makes reporting fast, simple and cost-effective with an added benefit, and a specialized knowledge is not required for its use. MARLI was tested for the collection of landslides in Cuenca (Ecuador). From the data taken in the field, it was possible to analyze the performance and suitability of collected data and compare the results with regional inventories in the same area. Additionally, these results can be used for the elaboration and update of large-scale inventories or the training of automatic identification systems of landslides and later evaluation of their precision in a small-medium scale. Likewise, this product constitutes a fundamental input for the formulation of mitigation strategies, to formulate the appropriate response and in time, also the elaboration of reconstruction plans before the increase in the occurrence of such phenomenaSIThis study was supported by the Land Laboratory Research Group (G.I.-1934-TB) (Universidade de Santiago de Compostela, Spain) and the University of Azuay (Cuenca, Ecuador) (Project No: 2016-53)

Application of satellite images to locate and inventory vineyards in the designation of origin "Bierzo" in Spain

P. 277-290With a view to contributing to the improvement of the current vineyard registers, this study presents a methodology for vineyard mapping based on satellite remote sensing systems. The procedure was validated for the Designation of origin "Bierzo" in Spain. Different supervised classifications were performed besed on two Landsat images acquired in the same year. The objetives of the present study were to determine which classification yielded the best results and to quantify the influence of different factors that affected the overall classification accuracy, such as the resampling method, the use of georeferenced mosaics, or the combination of the two imagesS

Sistema de información catastral adaptado a la realidad del gobierno local en Ecuador. El caso de la parroquia Vilcabamba (Loja)

El catastro constituye un elemento básico para administrar el territorio. Actualmente, las municipalidades de Ecuador empiezan a incursionar en este tema, pero a menudo la falta de experiencia produce el estancamiento de procesos y agotamiento de recursos. Para aportar en el fortalecimiento de estas iniciativas, el presente proyecto de cooperación interuniversitaria tuvo una doble finalidad: capacitar a técnicos locales en la creación e implementación de Sistemas de Información Geográfica Catastral (SIGC) y aplicar los conocimientos adquiridos mediante la puesta en marcha de un proyecto piloto a nivel local. Una vez analizada la realidad catastral y realizada la capacitación, se realizó e implantó el SIGC para la parroquia Vilcabamba (Ecuador). Se pudo concluir que es posible establecer SIGC eficientes en municipios con pocos recursos, si bien la sostenibilidad en el tiempo no queda garantizada.Peer Reviewe

Algorithm based on simulated annealing for land use allocation

This article describes the use of simulated annealing for allocation of land units to a set of possible uses on, the basis of their suitability for those uses, and the compactness of the total areas allotted to the same use or kind of use, which are fixed a priori. The results obtained for the Terra Chá district of Galicia (N.W. Spain) using different objective weighting schemes are compared with each other and with those obtained for this district under the same area constraints, using hierarchical optimization, ideal point analysis, and multi-objective land allocation (MOLA) to maximize average use suitability. Inclusion of compactness in the simulated annealing objective function avoids the highly disperse allocations typical of optimizations that ignore this sub-objectiveS

Forest Road Detection Using LiDAR Data and Hybrid Classification

Knowledge about forest road networks is essential for sustainable forest management and fire management. The aim of this study was to assess the accuracy of a new hierarchical-hybrid classification tool (HyClass) for mapping paved and unpaved forest roads with LiDAR data. Bare-earth and low-lying vegetation were also identified. For this purpose, a rural landscape (area 70 ha) in northwestern Spain was selected for study, and a road network map was extracted from the cadastral maps as the ground truth data. The HyClass tool is based on a decision tree which integrates segmentation processes at local scale with decision rules. The proposed approach yielded an overall accuracy (OA) of 96.5%, with a confidence interval (CI) of 94.0–97.6%, representing an improvement over pixel-based classification (OA = 87.0%, CI = 83.7–89.8%) using Random Forest (RF). In addition, with the HyClass tool, the classification precision varied significantly after reducing the original point density from 8.7 to 1 point/m2. The proposed method can provide accurate road mapping to support forest management as an alternative to pixel-based RF classification when the LiDAR point density is higher than 1 point/m2This research was supported by: (1) the Project “Sistema de ayuda a la decisión para la adaptación al cambio climático a través de la planificación territorial y la gestión de riesgos (CLIMAPLAN) (PID2019-111154RB-I00): Proyectos de I+D+i - RTI”; and (2) “National Programme for the Promotion of Talent and Its Employability” of the Ministry of Economy, Industry, and Competitiveness (Torres-Quevedo program) via a postdoctoral grant (PTQ2018-010043) to Juan Guerra HernándezS

Spatial Planning of Green Infrastructure for Mitigation and Adaptation to Climate Change at a Regional Scale

Green infrastructure has acquired greater importance in recent years in relation to climate change adaptation. Green infrastructure planning has been identified as a new and innovative means of land planning that can contribute to preventing the impacts of climate change. However, this has been explored more thoroughly in urban areas than at the regional scale. The present study proposes a methodology including multi-criteria evaluation techniques for assessing the ESS involved in the fight against climate change and for the spatial planning of multifunctional green infrastructure areas based on the results of this assessment. Application of the methodology for green infrastructure planning aimed at confronting climate change at landscape level in the region of Galicia (NW Spain) successfully delimited multifunctional green infrastructure zones. Results show that delimited zones have a higher provision potential for more ESS than protected natural areas and areas that are not part of the green infrastructureThis research was funded by Fundación Biodiversidad of the Spanish Ministry of Ecological Transition, project title “INVERCLIMA—Infraestructura Verde para la adaptación de la ordenación territorial al cambio climático”S

Vineyard area estimation using medium spatial resolution satellite imagery

P. 441-452The European Union requires member states to estimate their wine growing potential. For this porpose, most member states have developed or updated vineyard registers. The present study suggests locating vineyards using medium spatial resolution satellite imagery. The work was carried out using Landsat images that were validated for the Designation of Origin "Bierzo", León, SpainS

La opinión de los agricultores gallegos sobre sus condiciones de vida, el desarrollo rural en Galicia

En la conferencia sobre Desarrollo Rural de Salzburgo en 2003, se reconocía la diversidad de Europa en cuanto a sus paisajes, sus sistemas de producción, así como a su capacidad de retener y atraer población. Es en este punto donde realizamos nuestra contribución, para que el hecho de pertenecer a un núcleo rural no suponga una depreciación de la calidad de vida y del bienestar. Surge así la necesidad de evaluación, no sólo de las necesidades de la población rural sino de la valoración del bienestar rural, entendido el término como complejo y de difícil valoración. Por otra parte, la Unión Europea señala que el desarrollo rural se basa en mejorar la calidad de vida, interviniendo en la calidad ambiental, el nivel de renta y las condiciones de vida y trabajo. La evaluación de la calidad de vida, se puede acometer mediante la creación de un marco conceptual de cálculo, donde se reflejen conjuntamente las distintas variables que intervienen en el análisis, mediante la creación de una batería de indicadores multivariable. En esta aproximación al conocimiento de la calidad de vida se realizó una diferenciación espacial en 22 comarcas de Galicia, tomando como base el concepto del bienestar rural y la opinión de los agricultores