Knowledge of water depth is a crucial for planning military amphibious operations. Bathymetry from remote sensing with multispectral or hyperspectral imagery provides an opportunity to acquire water depth data faster than traditional hydrographic survey methods without the need to deploy a hydrographic survey vessel. It also provides a means of collecting bathymetric data covertly. This research explores two techniques for deriving bathymetry and assesses them for use by those involved in providing support to military operations. To support this aim a fieldwork campaign was undertaken in May, 2000, in northern Queensland. The fieldwork collected various inherent and apparent water optical properties and was concurrent with airborne hyperspectral imagery collection, space-based multispectral imagery collection and a hydrographic survey. The water optical properties were used to characterise the water and to understand how they affect deriving bathymetry from imagery. The hydrographic data was used to assess the performance of the bathymetric techniques. Two methods for deriving bathymetry were trialled. One uses a ratio of subsurface irradiance reflectance at two wavelengths and then tunes the result with known water depths. The other inverts the radiative transfer equation utilising the optical properties of the water to derive water depth. Both techniques derived water depth down to approximately six to seven metres. At that point the Cowley Beach waters became optically deep. Sensitivity analysis of the inversion method found that it was most sensitive to errors in vertical attenuation Kd and to errors in transforming the imagery into subsurface irradiance reflectance, R(0-) units. Both techniques require a priori knowledge to derive depth and a more sophisticated approach would be required to determine water depth without prior knowledge of the area of interest. This research demonstrates that water depth can be accurately mapped with optical techniques in less than ideal optical conditions. It also demonstrates that the collection of inherent and apparent optical properties is important for validating remotely sensed imagery.

Forage quality is a principal factor in managing both herbivores and the landscapes they use. Nutrition varies across the landscape, and in turn, so do the distributions of these populations. With the rise of remote sensing technologies (i.e. satellites, unmanned aerial vehicles, and multi/hyperspectral sensors), comes the ability to index forage health and nutrition swiftly. However, no methodology has been developed which allows managers to use unmanned aerial systems to the fullest capacity. The following methodologies produce compelling evidence for predicting forage quality metrics (such as fiber, carbohydrates, and digestibility) using 5 measured bands of reflectance (Blue, Green, Red, Red Edge, and NIR), 3 derived vegetation indices (NDVI, EVI and VARI), and a variety of environmental factors (i.e. time and sun angles) in a LASSO framework. Fiber content, carbohydrates, and digestibility showed promising model performance in terms of goodness-of-fit (R2= 0.624, 0.637, and 0.639 respectively).

This research develops a methodology for determining farm scale land managementunits (LMUs) using soil sampling data, high resolution digital multi-spectral imagery (DMSI) and a digital elevation model (DEM). The LMUs are zones within a paddock suitable for precision agriculture which are managed according to their productive capabilities. Soil sampling and analysis are crucial in depicting landscape characteristics, but costly. Data based on DMSI and DEM is available cheaply and at high resolution.The design and implementation of a two-stage methodology using a spatiallyweighted multivariate classification, for delineating LMUs is described. Utilising data on physical and chemical soil properties collected at 250 sampling locations within a 1780ha farm in Western Australia, the methodology initially classifies sampling points into LMUs based on a spatially weighted similarity matrix. The second stage delineates higher resolution LMU boundaries using DMSI and topographic variables derived from a DEM on a 10m grid across the study area. The method groups sample points and pixels with respect to their characteristics and their spatial relationships, thus forming contiguous, homogenous LMUs that can be adopted in precision agricultural applications. The methodology combines readily available and relatively cheap high resolution data sets with soil properties sampled at low resolution. This minimises cost while still forming LMUs at high resolution.The allocation of pixels to LMUs based on their DMSI and topographic variables has been verified. Yield differences between the LMUs have also been analysed. The results indicate the potential of the approach for precision agriculture and the importance of continued research in this area.

L’interaction d’un faisceau laser de courte durée d’impulsion sur des matériaux tels que l’aluminium, le fer ou le titane est caractérisée par la présence d’une plume très énergétique et fortement ionisée (plasma). L'objectif de cette étude est de comprendre les mécanismes mis en jeu dans le plasma, créé lors de l'interaction laser-cible, qui conduisent à la formation de nanoparticules.Nous souhaitons étudier de façon générale la dynamique d’expansion dans l’air de la plume formée par un laser Nd :YAG déclenché de courte durée d’impulsion pour préciser les conditions de formation de ces particules et leurs caractéristiques morphologiques et structurales. Ainsi, ce travail se décompose en deux parties. Dans une première partie, nous présentons la caractérisation expérimentale de l’expansion de la plume dans l’air. Le rayonnement induit par le plasma permet d’extraire ses caractéristiques. Deux méthodes complémentaires ont été utilisées : la spectrométrie qui permet de faire une analyse physique du plasma et l’imagerie spectrale qui permet une analyse morphologique. La seconde partie est consacrée à la caractérisation des particules formées dans les mêmes conditions opératoires. Dans le but d’analyser les particules le plus proche de leur milieu de formation, une analyse « en vol » de la distribution en taille des particules est mise en œuvre par granulométrie EEPS. Cette expérience est préparatoire à une analyse par diffusion des rayons X aux petits angles (S.A.X.S.) sous atmosphère contrôlée, qui permet d’étudier l’influence de l’oxygène sur la taille et la morphologie des particules formées. / The interaction of a laser beam of short pulse duration with metallic materials such as aluminum, iron or titanium is characterized by the presence of a high energy and strongly ionized plume (plasma). The aim of this study is to understand the mechanisms involved in plasma, created when laser-target interaction, which lead to the formation of nanoparticles. We would generally consider the dynamic expansion in the air of the plasma plume formed with a nanosecond Nd:YAG laser to specify the conditions of formation of these particles and their morphological and structural characteristics. Thus, this work is divided onto two parts. In the first part, we present the experimental characterization of the expansion of the plume in the air. The radiation induced by plasma allows to extracting the plasma characteristics. Two complementary methods were used: atomic spectrometry which allows to doing a physical analysis of plasma and spectral fast imagery to obtain a morphological analysis. The second part is devoted to the characterization of particles formed in the same operating conditions. In order to analyzing the particles as close to their formation environment, an analysis “in flight” of particle size distribution is implemented by EEPS granulometry. This experiment is preparatory at an analysis by in-situ Small-Angle X-ray Scattering (S.A.X.S.) under a controlled atmosphere, which allows to studying the influence of oxygen on the size and the morphology of the particles.

La Tomographie Optique Diffuse (TOD) est désormais une modalité d’imagerie médicale fonctionnelle reconnue. L’une des applications les plus répandues de cette technique est celle de l’imagerie fonctionnelle cérébrale chez l’Homme. En effet, cette technique présente de nombreux avantages, notamment grâce à la richesse des contrastes optiques accessibles. Néanmoins, certains verrous subsistent et freinent le développement de son utilisation, spécialement pour des applications chez l’Homme adulte en clinique ou dans des conditions particulières comme lors du suivi de l’activité sportive. En effet, le signal optique mesuré contient des informations venant de différentes profondeurs de la tête, et donc de différents types de tissus comme la peau ou le cerveau. Or, la réponse d’intérêt étant celle du cerveau, la réponse de la peau peut dégrader l’information recherchée. Dans ce contexte, ces travaux portent sur le développement d’un nouvel instrument de TOD permettant d’acquérir les dimensions spatiale, spectrale et de temps de vol du photon de façon simultanée, et ce à haute fréquence d’acquisition. Au cours de cette thèse, l’instrument a été développé et caractérisé sur fantôme optique. Ensuite, il a été validé in-vivo chez l’Homme adulte, notamment en détectant l’activité du cortex préfrontal en réponse à une tâche de calcul simple. Les informations multidimensionnelles acquises par notre système ont permis d’améliorer la séparation des contributions des différents tissus (Peau/Cerveau). Elles ont également permis de différencier la signature de la réponse physiologique de ces tissus, notamment en permettant de détecter les variations de concentration en Cytochrome-c-oxydase. Parallèlement à ce développement instrumental, des simulations Monte-Carlo de la propagation de la lumière dans un modèle anatomique de tête ont été effectuées. Ces simulations ont permis de mieux comprendre la propagation de la lumière dans les tissus en fonction de la longueur d’onde et de valider la pertinence de cette approche multidimensionnelle. Les perspectives de ces travaux de thèse se dirigent vers l’utilisation de cet instrument pour le suivi de la réponse du cerveau chez l’Homme adulte lors de différentes sollicitations comme des stimulations de TDCS, ou en réponse à une activité sportive. / The Diffuse Optical Tomography (DOT) is now a relevant tool for the functional medical imaging. One of the most widespread application of this technic is the imaging of the human brain function. Indeed, this technic has numerous advantages, especially the richness of the optical contrast accessible. Nevertheless, some drawbacks are curbing the use of the technic, especially for applications on adults in clinics or in particular environment like in the monitoring of sports activity. Indeed, the measured signal contains information coming from different depths of the head, so it contains different tissues types like skin and brain. Yet, the response of interest is the one of the brain, and the one of the skin is blurring it. In this context, this work is about the development of a new instrument of DOT capable of acquiring spatial and spectral information, as well as the arrival time of photons simultaneously and at a high acquisition speed. During the PhD thesis the instrument has been developed and characterised on optical phantoms. Then, it has been validated in-vivo on adults, especially by detecting the cortical activation of the prefrontal cortex, in response to a simple calculation task. Multidimensional information acquired by our system allowed us to better distinguish between superficial and deep layers. It also allowed us to distinguish between the physiological signature of those tissues, and especially to detect the variations of concentration in Cytochrom-c-oxydase. Concurrently to this experimental work, Monte-Carlo simulation of light propagation in a model off a human head has been done. Those simulations allowed us to better understand the light propagation in tissues as function as their wavelength, and to validate the relevance of our multidimensional approach. Perspectives of this work is to use the developed instrument to monitor the brain’s response of the Human adult to several solicitations like tDCS stimulation, or sports activity.