National Geographic Institute
National Geographic Institute
Malpica J.A.,University of Alcalá |
Alonso M.C.,University of Alcalá |
Papi F.,National Geographic Institute |
Arozarena A.,National Geographic Institute |
De Agirrea A.M.,University of Alcalá
International Journal of Remote Sensing | Year: 2013
Geospatial objects change over time and this necessitates periodic updating of the cartography that represents them. Currently, this updating is done manually, by interpreting aerial photographs, but this is an expensive and time-consuming process. While several kinds of geospatial objects are recognized, this article focuses on buildings. Specifically, we propose a novel automatic approach for detecting buildings that uses satellite imagery and laser scanner data as a tool for updating buildings for a vector geospatial database. We apply the support vector machine (SVM) classification algorithm to a joint satellite and laser data set for the extraction of buildings. SVM training is automatically carried out from the vector geospatial database. For visualization purposes, the changes are presented using a variation of the traffic-light map. The different colours assist human operators in performing the final cartographic updating. Most of the important changes were detected by the proposed method. The method not only detects changes, but also identifies inaccuracies in the cartography of the vector database. Small houses and low buildings surrounded by high trees present significant problems with regard to automatic detection compared to large houses and taller buildings. In addition to visual evaluation, this study was checked for completeness and correctness using numerical evaluation and receiver operating characteristic curves. The high values obtained for these parameters confirmed the efficacy of the method. © 2013 Copyright Taylor and Francis Group, LLC.
vanden Berghe I.,National Geographic Institute |
Crompvoets J.,Kuleuven Public Management Institute |
de Vries W.,ITC Inc |
Stoter J.,Technical University of Delft
Official Publication - EuroSDR | Year: 2011
This report is the final report of the EuroSDR project "Atlas of INSPIRE Implementation Methods". In two two-day workshops and one pre-workshop of the INSPIRE Conference in Krakow, June, 2010 we investigated strategies to implement INSPIRE in several members states. We focused specifically on the relations between the implemented strategy and how successful the INSPIRE implementation is perceived in a specific country. A questionnaire was carried out as well. This report describes the project, presents the conclusions and contains the main deliverables of the project which are: Two workshop reports Research agenda for the implementation of INSPIRE A network of SDI-practitioners and scientists across Europe that are strongly involved in the development of INSPIRE SDI-strategies Scientific paper publications Scientific paper publications: published IJSDIR article  and article in progress for CEUS (Journal for Computers, Environment and Urban Systems) INSPIRE-Conference pre-conference workshop, abstract and presentation Key documents collection regarding INSPIRE-implementation Prototype INSPIRE atlas (see: http://www.spatialist.be) We are grateful to all participants of the workshops as well as to all who carefully completed the questionnaire. The exchange of knowledge and experiences has been a very valuable result to all of us.
Raposo-Pulido V.,National Geographic Institute |
Raposo-Pulido V.,Helmholtz Center Potsdam |
Heinkelmann R.,Helmholtz Center Potsdam |
Nilsson T.,Helmholtz Center Potsdam |
And 6 more authors.
International Association of Geodesy Symposia | Year: 2016
Earth Orientation Parameters (EOP) provide the rotation of the International Terrestrial Reference System (ITRS) to the Geocentric Celestial Reference System (GCRS) as a function of time. When estimating a Celestial Reference Frame (CRF) usually a number of radio sources with a long history of observations and stable positions are included in the datum used to define the orientation of the frame. How many and which radio sources are taken into account for the datum definition has a significant effect on the estimated EOP. In this study we analyze the effects of different options for the celestial datum definition on the precision of the EOP and on the agreement w.r.t the last realization of the International Celestial Reference Frame (ICRF2; Fey et al., The second realization of the international celestial reference frame by very long baseline interferometry, IERS Technical Note No. 35, 2009). The resulting EOP of the special VLBI session IYA09 are compared to the C04 08 EOP series (Bizouard and Gambis, The combined solution C04 for Earth orientation parameters consistentwith international terrestrial reference frame 2008, IERS Notice 2011, 2011). The analysis shows that the smallest uncertainties for EOP are achieved when the maximum number of defining sources is chosen for the datum. Comparing with a typical VLBI session, the precision of the EOP and the agreement of the axes w.r.t. ICRF2 could be improved if more defining sources, especially in the southern hemisphere, were considered. © Springer International Publishing Switzerland 2015.
Perez-Hoyos A.,University of Valencia |
Garcia-Haro F.J.,University of Valencia |
Valcarcel N.,National Geographic Institute
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2014
Various global land cover (LC) datasets have been produced from remote sensing data in response to the need for information about LC. Nevertheless, the potential use of global LC products is often very limited by the lack of detailed accuracy information at regional to national level. This paper proposes a methodology for performing accuracy assessment of large-area LC products, which takes into account a number of factors arising from intrinsic characteristics of LC, such as thematic uncertainty that results from the partial overlap in legend definitions and lack of homogeneity within reference and classification data. © 2008-2012 IEEE.
Villa G.,National Geographic Institute |
Mas S.,National Geographic Institute |
Fernandez-Villarino X.,Ministry of Agriculture |
Martinez-Luceno J.,National Geographic Institute |
And 6 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016
Usual workflows for production, archiving, dissemination and use of Earth observation images (both aerial and from remote sensing satellites) pose big interoperability problems, as for example: non-alignment of pixels at the different levels of the pyramids that makes it impossible to overlay, compare and mosaic different orthoimages, without resampling them and the need to apply multiple resamplings and compression-decompression cycles. These problems cause great inefficiencies in production, dissemination through web services and processing in "Big Data" environments. Most of them can be avoided, or at least greatly reduced, with the use of a common "nested grid" for mutiresolution production, archiving, dissemination and exploitation of orthoimagery, digital elevation models and other raster data. "Nested grids" are space allocation schemas that organize image footprints, pixel sizes and pixel positions at all pyramid levels, in order to achieve coherent and consistent multiresolution coverage of a whole working area. A "nested grid" must be complemented by an appropriate "tiling schema", ideally based on the "quad-tree" concept. In the last years a "de facto standard" grid and Tiling Schema has emerged and has been adopted by virtually all major geospatial data providers. It has also been adopted by OGC in its "WMTS Simple Profile" standard. In this paper we explain how the adequate use of this tiling schema as common nested grid for orthoimagery, DEMs and other types of raster data constitutes the most practical solution to most of the interoperability problems of these types of data.,.
Hernandez Lopez D.,University of Castilla - La Mancha |
Felipe Garcia B.,University of Castilla - La Mancha |
Gonzalez Piqueras J.,University of Castilla - La Mancha |
Alcazar G.V.,National Geographic Institute
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2011
Harnessing the radiometric information provided by photogrammetric flights could be useful in increasing the thematic applications of aerial images. The aim of this paper is to improve relative and absolute homogenization in aerial images by applying atmospheric correction and treatment of bidirectional effects. We propose combining remote sensing methodologies based on radiative transfer models and photogrammetry models, taking into account the three-dimensional geometry of the images (external orientation and Digital Elevation Model). The photogrammetric flight was done with a Z/I Digital Mapping Camera (DMC) with a Ground Sample Distance (GSD) of 45. cm. Spectral field data were acquired by defining radiometric control points in order to apply atmospheric correction models, obtaining calibration parameters from the camera and surface reflectance images. Kernel-driven models were applied to correct the anisotropy caused by the bidirectional reflectance distribution function (BRDF) of surfaces viewed under large observation angles with constant illumination, using the overlapping area between images and the establishment of radiometric tie points. Two case studies were used: 8-bit images with applied Lookup Tables (LUTs) resulting from the conventional photogrammetric workflow for BRDF studies and original 12-bit images (Low Resolution Color, LRC) for the correction of atmospheric and bidirectional effects. The proposed methodology shows promising results in the different phases of the process. The geometric kernel that shows the best performance is the Lidense kernel. The homogenization factor in 8-bit images ranged from 6% to 25% relative to the range of digital numbers (0-255), and from 18% to 35% relative to levels of reflectance (0-100) in the 12-bit images, representing a relative improvement of approximately 1-30%, depending on the band analyzed. © 2011 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).
Gonzalez-Riancho P.,University of Cantabria |
Gonzalez M.,University of Cantabria |
Gutierrez O.,University of Cantabria |
Garcia-Aguilar O.,University of Cantabria |
And 6 more authors.
Proceedings of the Coastal Engineering Conference | Year: 2012
Advances in the understanding and prediction of tsunami impacts allow the development of adaptation and mitigation strategies to reduce risk on coastal areas. This work, funded by the Spanish Agency for International Development Cooperation (AECID) during the period 2009-2012, presents a comprehensive methodology for tsunami risk assessment at any coastal area worldwide applied specifically in this case to the coast of El Salvador.