Now showing items 21-33 of 33

    • Evaluation of topographic correction algorithms on satellite images 

      Sola Torralba, Ion Upna (2016)   Tesis doctoral / Doktoretza tesia  OpenAccess
      Este trabajo contribuye al previamente limitado conocimiento acerca del rendimiento de los métodos de corrección topográfica proponiendo una nueva metodología de evaluación basada en imágenes sintéticas. Esta nueva metodología ...
    • Factors controlling sediment export in a small agricultural watershed in Navarre (Spain) 

      Giménez Díaz, Rafael Upna; Casalí Sarasíbar, Javier Upna; Grande Esteban, Ildefonso Upna; Díez Beregaña, Javier Upna; Campo-Bescós, Miguel Upna; Álvarez-Mozos, Jesús Upna; Goñi Garatea, Mikel Upna (Elsevier, 2012)   Artículo / Artikulua  OpenAccess
      It is recognised that the hydrological and erosion processes in watersheds are very much conditioned by the (inter)action of a number of variables. This paper covers a 15-year period of studying those factors that have ...
    • Influence of surface roughness measurement scale on radar backscattering in different agricultural soils 

      Martínez de Aguirre Escobar, Alejandro Upna; Álvarez-Mozos, Jesús Upna; Lievens, Hans; Verhoest, Niko E. C. (IEEE, 2017)   Artículo / Artikulua  OpenAccess
      Soil surface roughness strongly affects the scattering of microwaves on the soil surface and determines the backscattering coefficient (σ 0 ) observed by radar sensors. Previous studies have shown important scale issues ...
    • Influence of surface roughness sample size for C-band SAR backscatter applications on agricultural soils 

      Martínez de Aguirre Escobar, Alejandro Upna; Álvarez-Mozos, Jesús Upna; Lievens, Hans; Verhoest, Niko E. C.; Giménez Díaz, Rafael Upna (IEEE, 2017)   Artículo / Artikulua  OpenAccess
      Soil surface roughness determines the backscatter coefficient observed by radar sensors. The objective of this letter was to determine the surface roughness sample size required in synthetic aperture radar applications and ...
    • Influence of surface roughness spatial variability and temporal dynamics on the retrieval of soil moisture from SAR observations 

      Álvarez-Mozos, Jesús Upna; Verhoest, Niko E. C.; Larrañaga, Arantzazu Upna; Casalí Sarasíbar, Javier Upna; González de Audícana Amenábar, María Upna (MDPI, 2009)   Artículo / Artikulua  OpenAccess
      Radar-based surface soil moisture retrieval has been subject of intense research during the last decades. However, several difficulties hamper the operational estimation of soil moisture based on currently available ...
    • Multi-criteria evaluation of topographic correction methods 

      Sola Torralba, Ion Upna; González de Audícana Amenábar, María Upna; Álvarez-Mozos, Jesús Upna (Elsevier, 2016)   Artículo / Artikulua  OpenAccess
      In the last decades, several topographic correction methods (TOC) have been proposed, but there is not an agreement on the best method. Furthermore, different evaluation criteria have been used in the past, and there is ...
    • Multitemporal evaluation of topographic correction algorithms using synthetic images 

      Sola Torralba, Ion Upna; Álvarez-Mozos, Jesús Upna; González de Audícana Amenábar, María Upna; Torres Escribano, José Luis Upna (SPIE, 2012)   Contribución a congreso / Biltzarrerako ekarpena  OpenAccess
      Land cover classification and quantitative analysis of multispectral data in mountainous regions is considerably hampered by the influence of topography on the spectral response pattern. In the last years, different ...
    • On the added value of quad-pol data in a multi-temporal crop classification framework based on RADARSAT-2 imagery 

      Larrañaga, Arantzazu Upna; Álvarez-Mozos, Jesús Upna (MDPI, 2016)   Artículo / Artikulua  OpenAccess
      Polarimetric SAR images are a rich data source for crop mapping. However, quad-pol sensors have some limitations due to their complexity, increased data rate, and reduced coverage and revisit time. The main objective of ...
    • On the assimilation set-up of ASCAT soil moisture data for improving streamflow catchment simulation 

      Loizu Maeztu, Javier Upna; Massari, Christian; Álvarez-Mozos, Jesús Upna; Tarpanelli, Angelica; Brocca, Luca; Casalí Sarasíbar, Javier Upna (Elsevier, 2018)   Artículo / Artikulua
      Assimilation of remotely sensed surface soil moisture (SSM) data into hydrological catchment models has been identified as a means to improve stream flow simulations, but reported results vary markedly depending on the ...
    • On the soil roughness parameterization problem in soil moisture retrieval of bare surfaces from synthetic aperture radar 

      Verhoest, Niko E. C.; Lievens, Hans; Wagner, Wolfgang; Álvarez-Mozos, Jesús Upna; Moran, M. Susan; Mattia, Francesco (MDPI, 2008)   Artículo / Artikulua  OpenAccess
      Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil ...
    • Photogrammetrical and field measurement of gullies with contrasting morphology 

      Marzolff, I.; Giménez Díaz, Rafael Upna; Seeger, M.; Campo-Bescós, Miguel Upna; Ries, J. B.; Casalí Sarasíbar, Javier Upna; Álvarez-Mozos, Jesús Upna (Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007)   Contribución a congreso / Biltzarrerako ekarpena  OpenAccess
      Despite a wealth of studies on monitoring different types of gullies by using remote-sensing technique such as photogrammetry, relatively few efforts have been made to test their accuracy. Therefore the question arises ...
    • Synthetic images for evaluating topographic correction algorithm 

      Sola Torralba, Ion Upna; González de Audícana Amenábar, María Upna; Álvarez-Mozos, Jesús Upna; Torres Escribano, José Luis Upna (IEEE, 2013)   Artículo / Artikulua  OpenAccess
      In the last years, many topographic correction (TOC) methods have been proposed to correct the illumination differences between the areas observed by optical remote sensors. Although the available number of TOC methods is ...
    • Validation of a simplified model to generate multispectral synthetic images 

      Sola Torralba, Ion Upna; González de Audícana Amenábar, María Upna; Álvarez-Mozos, Jesús Upna (MDPI, 2015)   Artículo / Artikulua  OpenAccess
      A new procedure to assess the quality of topographic correction (TOC) algorithms applied to remote sensing imagery was previously proposed by the authors. This procedure was based on a model that simulated synthetic scenes, ...