Flux limited generalized porous media diffusion equations

We study a class of generalized porous media type flux limited diffusion equations and we prove the existence and uniqueness of entropy solutions. We compute the Rankine-Hugoniot condition on the jump set for solutions which are of locally bounded variation in space and time. We give also a geometric characterization of the entropy conditions on the jump set for a restricted class of this type of equations

Journal Staff

This book constitutes the refereed proceedings of the 18th Scandinavian Conference on Image Analysis, SCIA 2013, held in Espoo, Finland, in June 2013. The 67 revised full papers presented were carefully reviewed and selected from 132 submissions. The papers are organized in topical sections on feature extraction and segmentation, pattern recognition and machine learning, medical and biomedical image analysis, faces and gestures, object and scene recognition, matching, registration, and alignment, 3D vision, color and multispectral image analysis, motion analysis, systems and applications, human-centered computing, and video and multimedia analysis

On Strongly Stable Approximations

Sin resume

Determining water use of sorghum from two-source energy balance and radiometric temperatures

Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (<i>Sorghum bicolor</i>) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h<sup>−1</sup> and ±1.0 mm d<sup>−1</sup> were obtained at hourly and daily scales, respectively. Total accumulated crop water use during the campaign was underestimated by 5%. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management

Estimación de la evaporación/transpiración en un cultivo de viña mediante radiometría térmica

La estimación precisa de la evapotranspiración de cultivo (ETc), así como su partición en las componentes evaporativa (E) y transpirativa (T), resultan fundamentales para mejorar la eficacia en la gestión del riego de cultivos en hilera en regiones áridas y semiáridas. El objetivo de este trabajo es contribuir a un mejor entendimiento de la partición E/T sobre viña llevando a cabo un balance de energía por separado para las componentes de suelo y de vegetación. En este trabajo se presentan los resultados de un experimento llevado a cabo en la finca de Las Tiesas, Albacete, de junio a octubre de 2013. Se instalaron un conjunto de radiómetros de infrarrojo térmico, apuntando directamente a las plantas y al suelo entre hileras. Se tomaron medidas de las cuatro componentes de la radiación neta, del flujo de calor en el suelo, además de variables meteorológicas y parámetros biofísicos. Todas las medidas se almacenaron en intervalos de 15 minutos, y se promediaron después a escala horaria y diaria. El valor medio observado de ETc fue de 3,1 mm día-1. La evaporación se estimó en torno al 30%. Los resultados presentados en este trabajo ofrecen una primera impresión de la partición E/T, y muestran el potencial de la caracterización térmica de la viña con este finAn accurate estimation of crop evapotranspiration (ETc), and its partition into both components, soil evaporation (E) and canopy transpiration (T), is known to be critical for a more effective irrigation scheduling of row-crops in arid and semi-arid environments. Vineyards are the best example in Mediterranean countries. The aim of this work is to improve our understanding of the E/T partition in vineyards by establishing a separate energy balance for soil and canopy components. An experiment was conducted in Las Tiesas experimental farm, Albacete (Spain), from June to October of 2013. A set of thermal-infrared radiometers were assembled pointing directly to the plants and the soil between rows. Measurements of the four components of the net radiation over the canopy and soil heat fluxes, as well as meteorological variables and biophysical parameters were all collected and stored every 15-min. Hourly and daily averages were then computed and analyzed. An average daily ETc value of 3.1 mm day-1 was observed in both sites. Interrow soil evaporation reached as much as 30% of the total ETc. These results provide a first insight into the partition E/T and show the potential of the vine thermal characterization with this aim.Ministerio de Economía y Competitividad CGL2013-46862-C2-1/2-PUnión Europea, AGL2014-54201-C4-4-RInstituto Nacional de Investigaciones Agrarias RTA 2011-00100-C05-04Instituto Nacional de Investigaciones Agrarias RTA 2014-00049-C05-03Generalitat Valenciana PROMETEOII/2014/08

Levelset and B-spline deformable model techniques for image segmentation: a pragmatic comparative study

International audienceDeformable contours are now widely used in image segmentation, using different models, criteria and numerical schemes. Some theoretical comparisons between some deformable model methods have already been published. Yet, very few experimental comparative studies on real data have been reported. In this paper,we compare a levelset with a B-spline based deformable model approach in order to understand the mechanisms involved in these widely used methods and to compare both evolution and results on various kinds of image segmentation problems. In general, both methods yield similar results. However, specific differences appear when considering particular problems

Combining Contrast Invariant L1 Data Fidelities with Nonlinear Spectral Image Decomposition

This paper focuses on multi-scale approaches for variational methods and corresponding gradient flows. Recently, for convex regularization functionals such as total variation, new theory and algorithms for nonlinear eigenvalue problems via nonlinear spectral decompositions have been developed. Those methods open new directions for advanced image filtering. However, for an effective use in image segmentation and shape decomposition, a clear interpretation of the spectral response regarding size and intensity scales is needed but lacking in current approaches. In this context, $L^1$ data fidelities are particularly helpful due to their interesting multi-scale properties such as contrast invariance. Hence, the novelty of this work is the combination of $L^1$-based multi-scale methods with nonlinear spectral decompositions. We compare $L^1$ with $L^2$ scale-space methods in view of spectral image representation and decomposition. We show that the contrast invariant multi-scale behavior of $L^1-TV$ promotes sparsity in the spectral response providing more informative decompositions. We provide a numerical method and analyze synthetic and biomedical images at which decomposition leads to improved segmentation.Comment: 13 pages, 7 figures, conference SSVM 201