La infraestructura de datos de biodiversidad de Navarra: una experiencia compartida

La infraestructura de datos de biodiversidad de navarra (IDBD), surge en el año 2007 como una especialización de la IDE regional (IDENA) aplicada a la biodiversidad, pretende incorporar y fomentar la interoperabilidad con iniciativas similares y en su desarrollo se tienen en cuenta las necesidades de múltiples tipos de usuarios (http://www.biodiversidad.navarra.es). Ante las dificultades en el acceso y tratamiento de la información geográfica y alfanumérica vinculada a la conservación de la biodiversidad (múltiples fuentes, muchos usuarios y con necesidades diferentes, gran variabilidad de métodos de captura de datos y, en muchos casos, información parcial, incompleta, mal documentada o antigua), el Gobierno de Navarra decidió superar esta situación a través de la creación de un proyecto compartido. En él participan múltiples actores, desde divulgadores a investigadores, utiliza y fomenta la definición y utilización de estándares de interoperabilidad y de modelos de datos y metadatos La apuesta por dar a la IDBD el carácter de “infraestructura” es consecuencia del “estado del arte” en la región: existencia de voluntad política y técnica con un gran impulso a la modernización de los servicios públicos, gran madurez y facilidades que ofrece la tecnología de la mano de la sociedad pública Tracasa, gran disponibilidad de información en el proyecto corporativo SITNA (Sistema de Información territorial de Navarra), necesidad de dar el mejor cumplimiento a los mandatos de la Ley 27/2006 y Directiva 2003/4/CE de acceso a la información ambiental y la participación de Gobierno regional y sociedad instrumental como socios en el proyecto Nature-SDI plus que trata sobre estos temas dentro de la Directiva INSPIRE. En este XIV Congreso Nacional de Tecnologías de la Información Geográfica se presentará la nueva versión de su frontal en Internet, con una presentación renovada y más operativa y el nuevo módulo de carga y geo-referenciación de fotografías, las claves del proyecto y las necesidades definidas por los usuarios y, con especial atención, los servicios Web que facilitan al acceso a la información alfanumérica, geográfica y multimedia sobre biodiversidad.Biodiversity Data Infrastructure of Navarre (IDBD) begins in the year 2007 as a specialization of the regional SDI (IDENA) applied to the topic of biodiversity. It intends to incorporate and promote interoperability with similar initiatives and with special attention to the user needs perspective (http://www.biodiversidad.navarra.es/?lg=en). Given the difficulties in access and treatment of geographic and alphanumeric information related to the biodiversity conservation (variety of sources, many people with different needs, great variability of data collection methods and in many cases, partial or incomplete information, poorly documented or old), the Government of Navarra decided to overcome this situation through the creation of a shared project. It involves multiple actors, from researchers to scientific speakers, and uses and encourages the definition and use of interoperability standards and data models and metadata The commitment to give the IDBD the character of "infrastructure" is consequence on the "state of the art” in the region: existence of political support and technical cooperation fostering the modernization of public services, maturity and facilities offered by the technology provided by the public company Tracasa, wide availability of information in the corporate project SITNA (Territorial Information System of Navarra), need for better compliance with the mandates of the Law 27/2006 and Directive 2003/4/EC on access to environmental information and the participation of regional government and public company as partners in the project Nature-SDI plus dealing with these issues within the framework of the INSPIRE directive. New and updated version of the IDBD will be presented at the XIV National Congress of Geographic Information Technology. A renewed and more operational home web site and the new module loading and geo-reference of photographs are currently the project keys. Additionally the identified user needs will be presented, with special attention to the web services that facilitate access to the alphanumeric, geographical and multimedia biodiversity contents

Quality test of interpolation methods on steepness regions for the use in surface modelling

Modeliranje površine je široko korištena metodologija u svim vrstama istraživanja vezanih za tlo. Postoje mnoge metode interpolacije koje se koriste za razvijanje modela uporabom mjernih točaka, uzoraka, na tlu. Dobivena kvaliteta određene metode interpolacije uvelike ovisi o točnosti, količini i raspodjeli izabranih uzoraka koji odražavaju topografiju proučavanog područja. Cilj je ovoga rada ispitati kvalitetu četiriju metoda interpolacije, odnosno metoda Kriging, Modified Shepard’s, inverzno ponderiranje udaljenosti i Radial Basis Function, uzimajući u obzir visinske razlike između susjednih mjesta. Za provjeru kvalitete visinskih komponenti u okviru proučavanog područja, dobivenih primjenom različitih modela interpolacije, kreirane su četiri umjetne površine naglih promjena visine. Odstupanja od standarda korištena za usporedbu kvalitete modela interpolacije određena su primjenom razlika između vrijednosti visina na kontrolnim točkama. Te su vrijednosti uzete kao prave i interpolirane vrijednosti za iste točke.Surface modelling has been a widely used methodology for interdisciplinary facilities in all kinds of earth-related studies. There are many interpolation methods applied for model generation using the measured points, samples, on the ground. The quality of the outcomes of an interpolation method is highly related to the accuracy, quantity, and distribution of the selected samples reflecting the topography within the study area. This study aims to examine the quality of four interpolation methods, namely the methods Kriging, Modified Shepard’s, Inverse distance weighting, and Radial Basis Function, considering height differences between the neighbour stations. To check the quality of height components within the study area derived applying different interpolation models, four artificial surfaces with sudden height changes were created. The standard deviations used for comparison of the quality of interpolation models were determined using differences between the height values of control points. These values were set as true and interpolated values for the same points

Airborne LiDAR for DEM generation: some critical issues

Airborne LiDAR is one of the most effective and reliable means of terrain data collection. Using LiDAR data for DEM generation is becoming a standard practice in spatial related areas. However, the effective processing of the raw LiDAR data and the generation of an efficient and high-quality DEM remain big challenges. This paper reviews the recent advances of airborne LiDAR systems and the use of LiDAR data for DEM generation, with special focus on LiDAR data filters, interpolation methods, DEM resolution, and LiDAR data reduction. Separating LiDAR points into ground and non-ground is the most critical and difficult step for DEM generation from LiDAR data. Commonly used and most recently developed LiDAR filtering methods are presented. Interpolation methods and choices of suitable interpolator and DEM resolution for LiDAR DEM generation are discussed in detail. In order to reduce the data redundancy and increase the efficiency in terms of storage and manipulation, LiDAR data reduction is required in the process of DEM generation. Feature specific elements such as breaklines contribute significantly to DEM quality. Therefore, data reduction should be conducted in such a way that critical elements are kept while less important elements are removed. Given the highdensity characteristic of LiDAR data, breaklines can be directly extracted from LiDAR data. Extraction of breaklines and integration of the breaklines into DEM generation are presented

Impact of DEM Resolution and Spatial Scale: Analysis of Influence Factors and Parameters on Physically Based Distributed Model

Physically based distributed hydrological models were used to describe small-scale hydrological information in detail. However, the sensitivity of the model to spatially varied parameters and inputs limits the accuracy for application. In this paper, relevant influence factors and sensitive parameters were analyzed to solve this problem. First, a set of digital elevation model (DEM) resolutions and channel thresholds were generated to extract the hydrological influence factors. Second, a numerical relationship between sensitive parameters and influence factors was established to define parameters reasonably. Next, the topographic index (TI) was computed to study the similarity. At last, simulation results were analyzed in two different ways: (1) to observe the change regularity of influence factors and sensitive parameters through the variation of DEM resolutions and channel thresholds and (2) to compare the simulation accuracy of the nested catchment, particularly in the subcatchments and interior grids. Increasing the grid size from 250 m to 1000 m, the TI increased from 9.08 to 11.16 and the Nash-Sutcliffe efficiency (NSE) decreased from 0.77 to 0.75. Utilizing the parameters calculated by the established relationship, the simulation results show the same NSE in the outlet and a better NSE in the simple subcatchment than the calculated interior grids

Ground Filtering Algorithms for Airborne LiDAR Data: A Review of Critical Issues

This paper reviews LiDAR ground filtering algorithms used in the process of creating Digital Elevation Models. We discuss critical issues for the development and application of LiDAR ground filtering algorithms, including filtering procedures for different feature types, and criteria for study site selection, accuracy assessment, and algorithm classification. This review highlights three feature types for which current ground filtering algorithms are suboptimal, and which can be improved upon in future studies: surfaces with rough terrain or discontinuous slope, dense forest areas that laser beams cannot penetrate, and regions with low vegetation that is often ignored by ground filters

Extraction of Urban Environmental Quality Indicators using LiDAR-Based Digital Surface Models

The visualization of specific 3-D urban scenes can be done calling upon different techniques, from those more traditional, such as photogrammetry, to the most advanced ones, such as laser scanning that uses different techniques and algorithms of selection and modelling of 3-D point clouds. The use and utility of this kind of data for the study of urban development remain however debatable. Indeed, indicators for urban development and durability are highly necessary and the best methodology to build them is largely open. This thesis anticipates the use of 2-D and 3-D models and data for the environmental analysis of cities, aiming to provide useful tools for urban planning and design. According to end-users requirements, the extraction of urban environmental quality (UEQ) indicators from 2-D and 3-D information using innovative methods is proposed and implemented, which is based on recent research on computational algorithms for the analysis, evaluation, management and design of the urban space. Moreover, results that can be obtained with different data sources and aggregation methods are compared. In particular, the main advantages of urban models generated from LiDAR data are highlighted. In consequence, an iterative process is proposed, involving professionals of various fields, aiming at improving the utility of those indicators for the support of applied decision activities related to the sustainable development of cities. This process is sub-divided in three correlated steps: A preliminary inquiry concerning the user requirements for the implementation of a 3-D project of the State/City of Geneva was launched. Based on the obtained replies, several potential applications related to both the definition and extraction of urban indicators were identified, and also, end-users were classified into 6 different domains: 1– architecture, urbanism and territory planning; 2– urban traffic (motor vehicles, trains and airplanes); 3– environment and energy; 4– pedestrian and cyclist mobility; 5– security and emergency situations management; 6– underground information; Based on point 1. and according to the assessment of the specific needs among each of these domains, several interviews were carried out in which 25 end-users decided to focus on UEQ indicators considering three main stakes: 1– assessment of the morphological properties of the urban texture; 2– exploration of the solar potential on the urban fabric; 3– estimation of the energy demand on the urban fabric. Many empirical case-studies are emphasized, mostly for the city of Geneva, and also for the cities of Lausanne and Florence. These indicators are extracted from the segmentation of planar roof areas using classified LiDAR point clouds and the use of image processing techniques based on Digital Elevation Models (DEM) and Digital Height Models (DHM), defined in this thesis as 2.5-Digital Urban Surface Models (2.5-DUSM) and normalized 2.5-Digital Urban Surface Models (n2.5-DUSM) respectively. These models are constructed in a step by step basis, using LiDAR and 2-D and 3-D vector data, thus applying different methods of interpolation and enhancement, whose accuracy is also evaluated on a statistical basis; Finally, an inquiry on how the same group of 25 end-users mentioned in point 1. perceives and interprets the different exploratory 2-D and 3-D geo-visualizations proposed for some of the UEQ indicators is undertaken, evaluating their utility according to the requirements previously defined