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Titre : Spatial data quality : from description to application Type de document : Thèse/HDR Auteurs : Pepijn Van Oort, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2005 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 60 Importance : 125 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-295-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données
[Termes IGN] base de données d'occupation du sol
[Termes IGN] covariance
[Termes IGN] données localisées
[Termes IGN] erreur de classification
[Termes IGN] généalogie des données
[Termes IGN] incertitude des données
[Termes IGN] occupation du sol
[Termes IGN] précision de la classification
[Termes IGN] qualité des données
[Termes IGN] terminologie
[Termes IGN] varianceRésumé : (Auteur) The growing availability of spatial data along with growing ease to use the spatial data (thanks to wide-scale adoption of GIS) have made it possible to use spatial data in applications inappropriate considering the quality of the data. As a result, concerns about spatial data quality have increased. To deal with these concerns, it is necessary to (1) formalise and standardise descriptions of spatial data quality and (2) to apply these descriptions in assessing the suitability (fitness for use) of spatial data, before using the data. The aim of this thesis was twofold: (1) to enhance the description of spatial data quality and (2) to improve our understanding of the implications of spatial data quality.
Chapter 1 sets the scene with a discussion on uncertainty and an explanation of why concerns about spatial data quality exist. Knowledge gaps are identified and the chapter concludes with six research questions.
Chapter 2 presents an overview of definitions of spatial data quality. Overall, I found a strong agreement on which elements together define spatial data quality. Definitions appear to differ in two aspects: (1) the location within the meta-data report: some elements occur not in the spatial data quality section but in another section of the meta-data report-, and (2) the explicitness with which elements are recognised as individual elements. For example, the European pre-standard explicitly recognises the element 'homogeneity'. Other standards recognise the importance of documenting the variation in quality, without naming it explicitly as an individual element.
In chapter 3, we quantified the spatial variability in classification accuracy for the agricultural crops in the Dutch national land cover database (LGN). Classification accuracy was significantly correlated with: (1) the crop present according to LGN, (2) the homogeneity of the 8-cell neighbourhood around each cell, (3) the size of the patch in which a cell is located, and (4) the heterogeneity of the landscape in which a cell is located.
In chapter 4, I present methods that use error matrices and change detection error matrices as input to make more accurate land cover change estimates. It was shown that temporal correlation in classification errors has a significant impact and must be taken into account. Producers of lime series land cover data are recommended not only to report error matrices, but also change detection error matrices.
Chapter 5 focuses on positional accuracy and area estimates. From the positional accuracy of vertices delineating polygons, the variance and covariance in area can be derived. Earlier studies derived equations for the variance, this chapter presents a covariance equation. The variance and covariance equation were implemented in a model and applied in a case-study. The case-study consisted of 97 polygons with a small subsidy value (in euros per hectare) assigned to each polygon. With the model we could calculate the uncertainty in the total subsidy value (in euros) of the complete set of polygons as a consequence of uncertainty in the position of vertices.
Chapter 6 explores the relationship between completeness of spatial data and risk in digging activities around underground cables and pipelines. A model is presented for calculating the economic implications of over- and incompleteness. An important element of this model is the relationship between detection lime and costs. The model can be used to calculate the optimal detection time, i.e. the time at which expected costs are at their minimum.
Chapter 7 addresses the question why risk analysis (RA) is so rarely applied to assess the suitability of spatial data prior to using the data. In theory, the use of RA is beneficial because it allows the user to judge if the use of certain spatial data does not produce unacceptable risks. Frequently proposed hypotheses explaining the scarce adoption of RA are all technical and educational. In chapter 7 we propose a new group of hypotheses, based on decision theory. We found that the willingness to spend resources on RA depends (1) on the presence of feedback mechanisms in the decision-making process, (2) on how much is at stake and (3) to a minor extent on how well the decision-making process can be modelled.
Chapter 8 prescrits conclusions on the six research questions (chapters 2-7) and lists recommendations for users, producers and researchers of spatial data. With regard to the description, four recommendations are given. Firstly, spend more effort on documenting the lineage of reference data. Secondly, quantify and report correlation of quality between related data sets. Thirdly, investigate the integration of different forms of uncertainty (error, vagueness, ambiguity). Fourthly, study the implementation and use of spatial data quality standards. With regard to the application of spatial data quality descriptions, I have two main recommendations. Firstly, to continue the line of research followed in this thesis: quantification of implications of spatial data quality, through development of theory along with tangible illustrations in case-studies. Secondly, there is a need for more empirical research into how users cope with spatial data quality.Numéro de notice : 13261 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Thèse étrangère DOI : sans En ligne : https://www.ncgeo.nl/downloads/60Oort.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54944 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 13261-02 37.00 Livre Centre de documentation Géomatique Disponible 13261-01 37.00 Livre Centre de documentation Géomatique Disponible A simple anisotropic model of the covariance function of the terrestrial gravity field over coastal areas / Jonathan Chenal in Newton's bulletin, n° 2 (December 2004)
[article]
Titre : A simple anisotropic model of the covariance function of the terrestrial gravity field over coastal areas Type de document : Article/Communication Auteurs : Jonathan Chenal , Auteur ; Jean-Pierre Barriot, Auteur Année de publication : 2004 Article en page(s) : 6 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anisotropie
[Termes IGN] covariance
[Termes IGN] géoïde gravimétriqueRésumé : (auteur) [introduction] The modelling of the gravity and of the geoid at the interface between continents and oceans is a very difficult challenge, as the gravity field over these regions exhibits large anisotropies. We consider in this short paper how to build simple 2D anisotropic covariance functions for collocation purposes. A detailed report is available upon request at BGI (Chenal, 2004). Numéro de notice : A2004-626 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100434
in Newton's bulletin > n° 2 (December 2004) . - 6 p.[article]Documents numériques
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A simple anisotropic model ... - pdf éditeurAdobe Acrobat PDF Regional simulation of ecosystem CO2 and water vapor exchange for agricultural land using NOAA AVHRR and Terra MODIS satellite data: Application to Zealand, Denmark / Rasmus M. Houborg in Remote sensing of environment, vol 93 n° 1 (30/10/2004)
[article]
Titre : Regional simulation of ecosystem CO2 and water vapor exchange for agricultural land using NOAA AVHRR and Terra MODIS satellite data: Application to Zealand, Denmark Type de document : Article/Communication Auteurs : Rasmus M. Houborg, Auteur ; H. Soegaard, Auteur Année de publication : 2004 Article en page(s) : pp 150 - 167 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] agriculture
[Termes IGN] atmosphère terrestre
[Termes IGN] couvert végétal
[Termes IGN] covariance
[Termes IGN] Danemark
[Termes IGN] dioxyde de carbone
[Termes IGN] flux
[Termes IGN] Green Leaf Area Index
[Termes IGN] image NOAA-AVHRR
[Termes IGN] image Terra-MODIS
[Termes IGN] indice de végétation
[Termes IGN] nuage
[Termes IGN] turbulence
[Termes IGN] vapeur d'eauRésumé : (Auteur) While accurate information on ecosystem C02 and water vapor exchange is available at eddy covariance flux tower sites, method, methods to expand predictions of C02 and energy exchange to regional or global scales with high fidelity are lacking. The main objective of this study was to examine the applicability of land surface and atmospheric products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Very High Resolution Radiometer (AVHRR) for assessing the spatial variation in C02 and water vapor fluxes for cloudless agricultural land pixels at the Island of Zealand, Denmark. The spatial distribution of green leaf area index, directbeam ark: diffuse solar radiation and air humidity was inferred on the basis of late morning MODIS data that was combined with afternoon AVHRR data to resolve the diurnal variation in air and surface temperature. These variables were used in a coupled "twoleaf' ecosystem model operating at an hourly time scale. The enhanced vegetation index (EVI) was strongly correlated with field measurements of green leaf area index (r2=0.91) and remained sensitive to variations in green biomass up to green leaf area indices of 45. Evaluation against standard meteorological data showed that instantaneous estimates of air temperature, actual vapor pressure and incoming solar radiation could be retrieved with overall root mean square errors of 2.5°C, 138.3 Pa and 47.7 Wm2, respectively. The combination of late morning and afternoon inferences made it possible to resolve the diurnal course in key model parameters, and predicted rates of ecosystem C02 and water vapor exchange were comparable to eddy covariance measurements at a single flux tower. A large spatial diversity in C02 and water vapor exchange was maintained throughout the study period due to significant regional variations in meteorological input variables and large spatial differences in canopy development. The results of this study stress the necessity of pixel based estimates for an accurate evaluation of regional budgets of C02 and water vapor exchange. Numéro de notice : A2004-426 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.07.001 En ligne : https://doi.org/10.1016/j.rse.2004.07.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26953
in Remote sensing of environment > vol 93 n° 1 (30/10/2004) . - pp 150 - 167[article]Two-step procedures for hybrid geoid modelling / Lard Erik Sjöberg in Journal of geodesy, vol 78 n° 1-2 (September 2004)
[article]
Titre : Two-step procedures for hybrid geoid modelling Type de document : Article/Communication Auteurs : Lard Erik Sjöberg, Auteur ; Will E. Featherstone, Auteur Année de publication : 2004 Article en page(s) : pp 66 - 75 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] covariance
[Termes IGN] estimateur
[Termes IGN] formule de Stokes
[Termes IGN] géoïde
[Termes IGN] géoïde gravimétrique
[Termes IGN] méthode des moindres carrés
[Termes IGN] pesanteur terrestre
[Termes IGN] varianceRésumé : (Auteur) A variety of mathematical models exist with which to combine long-wavelength geoid information from an Earth gravity model (EGM) with terrestrial gravity data. As new data become available, such as an extended or refined EGM and/or some variance-covariance information from terrestrial gravity data, this new information can be combined with a previous geoid model through a so-called hybrid estimator. The hybrid estimator is defined as a two-step estimator, which provides a solution that is a compromise between computational labour and matching of the entire data set. Some commonly used geoid modifications are compared, and several hybrid estimators are introduced. It is concluded that, in general, hybrid estimators linking the new information to old data by the least squares principle should be preferred to deterministic combinations. Numéro de notice : A2004-382 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-003-0367-9 En ligne : https://doi.org/10.1007/s00190-003-0367-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26909
in Journal of geodesy > vol 78 n° 1-2 (September 2004) . - pp 66 - 75[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-04032 RAB Revue Centre de documentation En réserve L003 Disponible 266-04031 RAB Revue Centre de documentation En réserve L003 Disponible Carbon mass fluxes of forests in Belgium determined with low resolution optical sensors / F. Veroustraete in International Journal of Remote Sensing IJRS, vol 25 n° 4 (February 2004)
[article]
Titre : Carbon mass fluxes of forests in Belgium determined with low resolution optical sensors Type de document : Article/Communication Auteurs : F. Veroustraete, Auteur ; H. Sabbe, Auteur ; D.P. Rasse, Auteur ; L. Bertels, Auteur Année de publication : 2004 Article en page(s) : pp 769 - 792 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] Belgique
[Termes IGN] bilan du carbone
[Termes IGN] classificateur paramétrique
[Termes IGN] corrélation
[Termes IGN] covariance
[Termes IGN] écosystème forestier
[Termes IGN] forêt
[Termes IGN] image NOAA-AVHRR
[Termes IGN] image optique
[Termes IGN] image SPOT-Végétation
[Termes IGN] turbulenceRésumé : (Auteur) The primary objective of this paper is to describe the validation of a parametric model (C-Fix) designed to estimate the basic carbon mass fluxes of forests in Belgium. Most validation efforts in the literature are based on point measurements. Since landscapes in Belgium are quite heterogeneous, the spatial up-scaling of a point measurement to the level of a sensor pixel is a crucial issue. Process based models quite often have a large set of input variables, some of them hardly available or not measurable on a regional basis; on the other hand most of the process based models possess a prognostic capacity. The parametric C-Fix model estimates carbon mass fluxes from local, regional to continental scales. It ingests only a modest number of meteorological input variables, including satellite observations. Parametric models do not possess a prognostic capacity, but the spatial up-scaling by the use of remote sensing data is much more straightforward than with process models. In this paper, we describe the validation of C-Fix with eddy covariance NEP (net ecosystem production) measurements and further applied C-Fix for the mapping of the geographical distribution of carbon mass fluxes over the entire Belgian territory, using NOAA-AVHRR (1997) and SPOT4-VGT imagery (April 1998-March 1999). We combine a forest probability map, derived from NOAA data for 1997 with the mapped estimates of Belgian NEP to obtain forest NEP per image pixel. Forest NEP is validated regionally, with measurements of carbon exchange obtained at two Belgian Euroflux eddy covariance tower sites (the Brasschaat, 'Inslag' and Vielsalm, 'Tinscubois' forest sites). A correlation analysis is performed for the estimated forest NEPs at both Euroflux sites and the NEP measured there, assumed to be primarily from forest. Finally, a correlation analysis with a process-based stand scale model (ASPECTS) is performed for the two forest sites, as a cross cheek on the validation results. Our results demonstrate that a parametric model, like C-Fix, provides a good basis to estimate the evolution and geographical distribution of the main constituents of the carbon budget of terrestrial ecosystems, in this study specifically forest ecosystems at the regional scale (Belgium). Numéro de notice : A2004-075 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115238 En ligne : https://doi.org/10.1080/0143116031000115238 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26603
in International Journal of Remote Sensing IJRS > vol 25 n° 4 (February 2004) . - pp 769 - 792[article]Exemplaires(1)
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