Potential and constraints of UAV technology for the characterisation of Mediterranean riparian forest: a case study of the Drôme, France - HAL Accéder directement au contenu
Chapitre d'ouvrage Année : 2007

Potential and constraints of UAV technology for the characterisation of Mediterranean riparian forest: a case study of the Drôme, France

Résumé

UAV technology allows large reaches of river to be surveyed at a high spatial resolution with little notice, providing potential for rapid, flexible mapping of relatively large areas at a user defined re-survey frequency. In areas such as the Drôme River in the Rhone Alps region of France where it has been hypothesised that poplar canopy degeneration is influenced by the reduction of groundwater as a result of channel incision these technologies provide a mechanism by which the scale of these impacts can be quantified. A radio controlled ?Pixy? UAV was used to collect 235 RGB digital camera images (ground resolution 6.8-21.8cm) in July 2005. These images were classified using both a standardised decision tree classification and an object oriented methodology as a means of determining the major vegetal units along the channel. The images were geo-rectified using 90 ground control points distributed along the corridor, positioned with a DGPS and joined into a classified river channel mosaic (RMSE 0.15). These mosaics were then validated against field data collected from field surveys within the channel. Poplar stands were then identified from the classified mosaics and the percentage of living vegetation, bare soil and dead wood within each stand was quantified. The methodology was shown to be successful at automating the differentiation between green forest vegetation, dead-wood and bare ground. Furthermore it was shown to be successful (kappa 0.73) at differentiating between the main species units of poplar, willow and pine. Differentiation within species (such as between different pine and willow species) proved more difficult. These findings are nonetheless encouraging considering the availability of only three spectral channels. The major constraints resulted from sensor movement during flight creating variations in spatial resolution and radiometry. It is hoped that with further research more complex methods of automated histogram correction will help refine the classification process.

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Dates et versions

halshs-00280057, version 1 (16-05-2008)

Identifiants

  • HAL Id : halshs-00280057 , version 1

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Robert Dunford, Kristell Michel, Hervé Piégay. Potential and constraints of UAV technology for the characterisation of Mediterranean riparian forest: a case study of the Drôme, France. Proceedings - ForestSat 07, Montpellier 5-7 nov, ForestSat, Pagination non précisée, 2007. ⟨halshs-00280057⟩
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