International audienceThe increasing availability of Very High Spatial Resolution images enables accurate digital maps production as an aid for management in the agricultural domain. In this study we develop a comprehensive and automatic tool for vineyard detection, delineation and characterizationusing aerial images and without any parcel plan availability. In France, vineyard training methods in rows or grids generate periodic patterns which make frequency analysis a suitable approach. The proposed method computes a Fast Fourier Transform on an aerial image, providing the delineation of vineyards and the accurate evaluation of row orientation and interrow width. These characteristics are then used to extract individual vine rows, with the aim of detecting missing vine plants and characterizing cultural practices. Using the red channel of an aerial image, 90\% of the parcels have been detected; 92\% have been correctly classified according to their rate of missing vine plants and 81\% according to their cultural practice (weed control method). The automatic process developed can be easily integrated into the final user's Geographical Information System and produces useful information for vineyard managemen
Abstract. A description of methods used to determine short-term changes in fire danger is reviewed, mainly those based on the estimation of foliage moisture content (FMC). Applications of low-resolution data, acquired by the Advanced Very High Resolution Radiometer (A VHRR) on board the NOAA satellites, as well those based on high-resolution data, are examined. Examples of FMC estimation on Mediterranean areas are also presented, both for A VHRR and Landsat-TM data. In both cases, satellite data provide a higher confidence to estimate FMC in grasslands than in shrublands, although in both cases, some variables provide significant correlation, especially when the spring season is taken into account. The most sensitive variables for FMC estimation are based on short-wave infrared bands, and the combination of vegetation indices and surface temperature.
3.1The role of foliage moisture content in the short-term estimation of fire dangerThe estimation of fire danger may be considered on different spatial and temporal scales. This chapter is focused on the contribution of satellite remote sensing data to estimate fire danger regarding the most dynamic factors of fire ignition or fire behaviour, while Chapter 5 deals with long-term trends of fire danger.As is well known, forest fire occurrence is a result of three main factors: a heat source, a fuel that burns, and oxygen (wind) to propagate combustion. Ignition sources may be natural or human-caused, the latter being the most common in the Mediterranean areas. Fuel refers to the different components of the vegetation layer, both live and dead materials. Atmospheric conditions influence both fire ignition and propagation, since they increases vegetation dryness and provides oxygen for fire propagation.Obviously, the contribution of remote sensing to fire danger estimation should be centred on determining fuel composition and state. The former addresses the question of a better understanding of factors related to vegetation structure, which in turn affect fire propagation. These are mainly the compactness, volume to surface ratio, vertical and horizontal continuity, and particle size. Since these vari-E. Chuvieco (ed.), Remote Sensing of Large Wildfires
-Due to their synoptic and monitoring capacities, Earth observation satellites could prove useful for the assessment and evaluation of drought effects in forest ecosystems. The objectives of this article are: to briefly review the existing sources of remote sensing data and their potential to detect drought damage; to review the remote sensing applications and studies carried out during the last two decades aiming at detecting and quantifying disturbances caused by various stress factors, and especially those causing effects similar to drought; to explore the possibility to use some of the different available systems for setting up a strategy more adapted to monitoring of drought effects in forests.drought / forest / remote sensing / satellite Résumé -Contribution de la télédétection à l'évaluation des effets de la sécheresse sur les écosystèmes forestiers. Grâce à leurs capacités de surveillance continue, les satellites d'observation de la Terre pourraient s'avérer utiles pour l'évaluation des effets de la sécheresse sur les écosystèmes forestiers. Les objectifs de cet article sont : de passer en revue rapidement les sources actuelles de données de télédétection et leur potentiel pour la détection des dommages dus à la sécheresse ; de passer en revue les études et applications de télédétection conduites pendant les deux dernières décennies et visant à détecter et quantifier les perturbations induites par différents facteurs de stress, et en particulier ceux causant des effets semblables à ceux de la sécheresse ; d'explorer la possibilité d'utiliser certains des systèmes disponibles pour définir une stratégie adaptée au suivi continu des effets de la sécheresse sur les forêts.sécheresse / forêt / télédétection / satellite
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