9,454 research outputs found
Analysis of urban sprawl at mega city Cairo, Egypt using multisensoral remote sensing data, landscape metrics and gradient analysis
This paper is intended to highlight the capabilities
of synergistic usage of remote sensing, landscape metrics and
gradient analysis. We aim to improve the understanding of
spatial characteristics and effects of urbanization on city level.
Multisensoral and multitemporal remotely sensed data sets
from the Landsat and TerraSAR-X sensor enable monitoring
a long time period with area-wide information on the spatial
urban expansion over time. Landscape metrics aim to quantify
patterns on urban footprint level complemented by gradient
analysis giving insight into the spatial developing of spatial
parameters from the urban center to the periphery. The
results paint a characteristic picture of the emerging spatial
urban patterns at mega city Cairo, Egypt since the 1970s
High-resolution optical and SAR image fusion for building database updating
This paper addresses the issue of cartographic database (DB) creation or updating using high-resolution synthetic aperture radar and optical images. In cartographic applications, objects of interest are mainly buildings and roads. This paper proposes a processing chain to create or update building DBs. The approach is composed of two steps. First, if a DB is available, the presence of each DB object is checked in the images. Then, we verify if objects coming from an image segmentation should be included in the DB. To do those two steps, relevant features are extracted from images in the neighborhood of the considered object. The object removal/inclusion in the DB is based on a score obtained by the fusion of features in the framework of DempsterâShafer evidence theory
Identification of Shadowed Areas to Improve Ragweed Leaf Segmentation
As part of a project targeting geometrical structure analysis and identification of ragweed leaves, sample images were created. Even though images were taken under near optimal conditions, the samples still contain noise of cast shadow. The proposed method improves chromaticity based primary shape segmentation efficiency by identification and re-classification of the shadowed areas. The primary classification of each point is done generally based on thresholding the Hue channel of Hue/Saturation/Value color space. In this work, the primary classification is enhanced by thresholding an intra-class normalized weight computed from the class specific Value channel. The corrective step is the removal of areas marked as shadow from the object class. The idea is based on the assumption that the image contains a single, flat leaf in front of a homogeneous background, but there are no color and illumination restrictions. Thus, parameters of the imaging system and the light sources have influence on homogeneity of image parts; however vague shadows differ only in intensity, and hard shadows can only be dropped on the background
Spaceborne SAR Small Boat Detection Campaign in Portugal and Spain
The European maritime area is one of Europeâs most important assets with regard to
resources, security and ultimately prosperity of the Member States. A significant part of Europeâs
economy relies directly or indirectly on it. It is not just the shipping or fisheries industries and
their related activities. It is also shipbuilding and ports, marine equipment and offshore energy,
maritime and coastal tourism, aquaculture, submarine telecommunications, blue biotech and the
protection of the marine environment. The European maritime area faces several risks and
threats posed by unlawful activities, such as drugs trafficking, smuggling, illegal immigration,
organised crime and terrorism. Piracy in international waters also constitutes a threat to Europe
since it can disrupt the maritime transport chain. These risks and threats can endanger human
lives, marine resources and the environment, as well as significantly disrupt the transport chain
and global and local security. It is anticipated that these risks and threats will endure in the mid
and long run. In order to keep Europe as a world leader in the global maritime economy, an
effective integrated/interoperable, sustainable maritime surveillance system and situational
awareness are needed.
A significant number of unlawful maritime activities, such as illegal immigration, drugs
trafficking, smuggling, piracy and terrorism involve mainly small boats, because small boats are
faster and more difficult to detect using conventional means. Hence, it is very important to find
out the feasibility of using SAR Satellite images for small boat detection. Since 2008 the EC-JRC
has carried out a number of SAR Small Boat detection experiments to assess the feasibility of
using Spaceborne SAR for Small Boat detection. This report presents the results and conclusions
of the Spaceborne SAR Small Boat detection campaign in inland sea waters and in coastal waters
carried out by the EC-JRC in the South of Spain (Sancti Petri-La Barossa, El Rompido, Punta
Umbria, Cadiz and Isla Cristina) and in Portugal (Sagres and Cascais) in December 2010. The
results of the experiment show that under suitable conditions of sea state, wind speed and
incidence angle it is possible to detect small boats in spaceborne SAR imagery in inland waters,
Coastal waters and open sea. Further research is needed to study possible correlations between
the empirical probability of detection of small boats in spaceborne SAR and the main parameters
involved, such as sea state, wind speed, incidence angle, among others.JRC.G.4-Maritime affair
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