Monocular-based 3-D seafloor reconstruction and ortho-mosaicing by piecewise planar representation

Photo-mosaicing techniques have become popular for seafloor mapping in various marine science applications. However, the common methods cannot accurately map regions with high relief and topographical variations. Ortho-mosaicing borrowed from photogrammetry is an alternative technique that enables taking into account the 3-D shape of the terrain. A serious bottleneck is the volume of elevation information that needs to be estimated from the video data, fused, and processed for the generation of a composite ortho-photo that covers a relatively large seafloor area. We present a framework that combines the advantages of dense depth-map and 3-D feature estimation techniques based on visual motion cues. The main goal is to identify and reconstruct certain key terrain feature points that adequately represent the surface with minimal complexity in the form of piecewise planar patches. The proposed implementation utilizes local depth maps for feature selection, while tracking over several views enables 3-D reconstruction by bundle adjustment. Experimental results with synthetic and real data validate the effectiveness of the proposed approach

Can salvage logging affect seed dispersal by birds into burned forests?

The recovery of vegetation in Mediterranean ecosystems after wildfire is mostly a result of direct regeneration, since the same species existing before the fire regenerate on-site by seeding or resprouting. However, the possibility of plant colonization by dispersal of seeds from unburned areas remains poorly studied. We addressed the role of the frugivorous, bird-dependent seed dispersal (seed rain) of fleshy-fruited plants in a burned and managed forest in the second winter after a fire, before on-site fruit production had begun. We also assessed the effect on seed rain of different microhabitats resulting from salvage logging (erosion barriers, standing snags, open areas), as well as the microhabitats of unlogged patches and an unburned control forest, taking account of the importance of perches as seed rain sites. We found considerable seed rain by birds in the burned area. Seeds, mostly from Olive trees Olea europaea and Evergreen pistaches Pistacia lentiscus, belonged to plants fruiting only in surrounding unburned areas. Seed rain was heterogeneous, and depended on microhabitat, with the highest seed density in the unburned control forest but closely followed by the wood piles of erosion barriers. In contrast, very low densities were found under perches of standing snags. Furthermore, frugivorous bird richness seemed to be higher in the erosion barriers than elsewhere. Our results highlight the importance of this specific post-fire management in bird-dependent seed rain and also may suggest a consequent heterogeneous distribution of fleshy-fruited plants in burned and managed areas. However, there needs to be more study of the establishment success of dispersed seeds before an accurate assessment can be made of the role of bird-mediated seed dispersal in post-fire regeneration

Signal processing of microstructure profiles: integrating turbulent spatial scales in aquatic ecological modeling

The main objective of this thesis was the integration of microstructure information in synoptic descriptors of turbulence, that reflects the mixing processes. Turbulent patches are intermittent in space and time, but they represent the dominant process for mixing. In this work, the properties of turbulent patches were considered the potential input for integrating the physical microscale measurements. The development of a method for integrating the properties of the turbulent patches required solving three main questions: a) how can we detect the turbulent patches from he microstructure measurements?; b) which are the most relevant properties of the turbulent patches?; and ) once an interval of time has been selected, what kind of synoptic parameters could better reflect the occurrence and properties of the turbulent patches? The answers to these questions were the final specific objectives of this thesis.

Cambios en la estructura del paisaje del Alt Empordà en el período 1957-2001

El paisaje, concebido como una unidad espacial y temporalmente pluriescalar caracterizada por unos patrones de distribución - una estructura-, unas funciones y una red de flujos de materia, energía e información (Forman y Godron, 1986), constituye un modelo apropiado para estudiar el territorio (Marull, 2002). En la presente investigación se hace un análisis de los cambios ocurridos en la estructura del mosaico paisajístico de la comarca de l´Alt Empordà entre 1957 y 2001, para ellos se divide la comarca en unidades paisajísticas basadas en criterios fisiográficos determinados a escala 1:25000. El análisis de la estructura paisajística de las diferentes unidades paisajísticas se ha realizado a través de indicadores de composición y de estructura según clases paisajísticas (cubiertas o usos del suelo), mediante el cálculo y análisis de indicadores de estructura desarrollados por la ecología del paisaje, los cuales, han permitido caracterizar y analizar las transformaciones en el tamaño, la forma y el arreglo espacial de los parches tipo que configuran el mosaico paisajístico. Para el proceso de cálculo y análisis espacial se han empleado los sistemas de información geográfica (SIGs), el programa Patch Analyst 1.2. La información cartográfica se elaboró a partir de ortofotomapas digitales y fotos aéreas generados por el ICC, así como de fuentes secundarias. Además, el trabajo incluye una aplicación teórico-metodológica a la identificación de redes ecológicas a través del uso de indicadores, así como el uso de inventarios fitosociológicos en la evaluación de hábitats borde.