Recovering facial shape using a statistical model of surface normal direction

In this paper, we show how a statistical model of facial shape can be embedded within a shape-from-shading algorithm. We describe how facial shape can be captured using a statistical model of variations in surface normal direction. To construct this model, we make use of the azimuthal equidistant projection to map the distribution of surface normals from the polar representation on a unit sphere to Cartesian points on a local tangent plane. The distribution of surface normal directions is captured using the covariance matrix for the projected point positions. The eigenvectors of the covariance matrix define the modes of shape-variation in the fields of transformed surface normals. We show how this model can be trained using surface normal data acquired from range images and how to fit the model to intensity images of faces using constraints on the surface normal direction provided by Lambert's law. We demonstrate that the combination of a global statistical constraint and local irradiance constraint yields an efficient and accurate approach to facial shape recovery and is capable of recovering fine local surface details. We assess the accuracy of the technique on a variety of images with ground truth and real-world images

Graph matching with a dual-step EM algorithm

This paper describes a new approach to matching geometric structure in 2D point-sets. The novel feature is to unify the tasks of estimating transformation geometry and identifying point-correspondence matches. Unification is realized by constructing a mixture model over the bipartite graph representing the correspondence match and by affecting optimization using the EM algorithm. According to our EM framework, the probabilities of structural correspondence gate contributions to the expected likelihood function used to estimate maximum likelihood transformation parameters. These gating probabilities measure the consistency of the matched neighborhoods in the graphs. The recovery of transformational geometry and hard correspondence matches are interleaved and are realized by applying coupled update operations to the expected log-likelihood function. In this way, the two processes bootstrap one another. This provides a means of rejecting structural outliers. We evaluate the technique on two real-world problems. The first involves the matching of different perspective views of 3.5-inch floppy discs. The second example is furnished by the matching of a digital map against aerial images that are subject to severe barrel distortion due to a line-scan sampling process. We complement these experiments with a sensitivity study based on synthetic data

A GEOMETRIC VARIATIONAL APPROACH TO SHAPE INVERSION FOR RADAR

In this thesis, we develop a novel method for dense shape reconstruction of scenes using radar. For a given scene and antennas taking measurements from the scene, our method iteratively estimates the scene shape using the measurements. To this end, we use a deformable shape evolution approach which seeks to match the received signal to a computed forward model based on the evolving shape. Adopting such an approach comes with important advantages such as the ability to naturally embed the shape priors into the estimation and being able to model self-occlusions which cannot be easily incorporated into classical radar imaging techniques. Iterations start with an initial shape model which is gradually deformed until its image under the forward model gets sufficiently close to the actual measurements. Since we use a gradient-based scheme to minimize our error and radar signals are highly oscillatory, a special attention is required to prevent these oscillations to manifest in the cost functional as local minima. For this purpose, we develop a novel technique by which we can extract the geometric information embedded in the radar signals that is used to formulate a well behaving cost functional. We test our approach with synthetic simulations performed in 2D which shows the promise of our approach on some challenging scenarios.Ph.D

Aeronautical Engineering: A continuing bibliography, supplement 120

This bibliography contains abstracts for 297 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980

Ice dynamics and glacial history from remote sensing of the Seno Skyring-Seno Otway-Strait of Magellan region, southernmost Patagonia

The glacial geomorphology of southernmost Patagonia records the advance and retreat of the Patagonian ice sheet over a number of glacial cycles. The well-preserved landform assemblages and sediments that have been left behind comprise one of the longest and most complete records of Quaternary glaciations in the world. Despite this, little is known about the pre-Last Glacial Maximum (LGM) ice sheet dynamics in a number of areas, particularly around the Strait of Magellan. This study has mapped in detail the glacial geomorphology of the Seno Skyring-Seno Otway-Strait of Magellan region from a combination of Landsat and ASTER satellite imagery and oblique and aerial photographs for the purposes of reconstructing the ice sheet dynamics. A wide variety of glacial landforms have been mapped, including glacial lineations, moraine ridges, meltwater channels, outwash plains and palaeo-shorelines. The most distinct features within the study area are highly elongate streamlined glacial lineations on the western side of the Strait of Magellan. A landsystems approach has been employed in order to decipher this group of lineations and three potentially plausible landsystems are evaluated: a palaeo-ice stream, a surging glacier, and an ice-marginal terrestrial landsystem. Based on the characteristic shape, dimensions and abrupt lateral margin of the flow-set, the lateral variation in lineation length and elongation ratios, and the presence of a potentially-deformable bed, these lineations are interpreted as being diagnostic of a terrestrial palaeo-ice stream. It is suggested that the initiation of ice streaming was caused by calving into one of two ice-dammed proglacial lakes. The lakes were located within the former Seno Skyring and Seno Otway ice lobes, which are well-defined by arcuate sequences of moraine ridges. The westernmost of the lakes, proglacial Lake Skyring, is delimited by a series of palaeo-shorelines surrounding the present-day lake Laguna Blanca. The size and orientation of meltwater channels and an outwash plain suggests that proglacial Lake Skyring drained eastwards towards the Strait of Magellan in an abrupt event. The ice sheet has been reconstructed at 10 time-steps, documenting stages of both advance and retreat. An attempt has been made to place this reconstruction within the framework of the wider glacial chronology of the region. From this, it is suggested that ice stream activity contributed to the rapid deglaciation of this sector of the ice sheet during the penultimate glaciation. Future work should focus on applying fieldwork to help validate the interpretations of this study. This should include dating of the landforms and sediments that have been mapped in order to improve the pre-LGM glacial chronology of this region, which is currently poorly-constrained

A review of modelling and analysis of morphing wings

Morphing wings have a large potential to improve the overall aircraft performances, in a way like natural flyers do. By adapting or optimising dynamically the shape to various flight conditions, there are yet many unexplored opportunities beyond current proof-of-concept demonstrations. This review discusses the most prominent examples of morphing concepts with applications to two and three-dimensional wing models. Methods and tools commonly deployed for the design and analysis of these concepts are discussed, ranging from structural to aerodynamic analyses, and from control to optimisation aspects. Throughout the review process, it became apparent that the adoption of morphing concepts for routine use on aerial vehicles is still scarce, and some reasons holding back their integration for industrial use are given. Finally, promising concepts for future use are identified

Aeronautical engineering: A continuing bibliography, supplement 122

This bibliography lists 303 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1980

Multisystem synthesis of radar sounding observations of the Amundsen Sea sector from the 2004‐2005 field season

The Amundsen Sea Embayment of the West Antarctic Ice Sheet contains Thwaites and Pine Island Glaciers, two of the most rapidly changing glaciers in Antarctica. To date, Pine Island and Thwaites Glaciers have only been observed by independent airborne radar sounding surveys, but a combined cross-basin analysis that investigates the basal conditions across the Pine Island-Thwaites Glaciers boundary has not been performed. Here, we combine two radar surveys and correct for their differences in system parameters to produce unified englacial attenuation and basal relative reflectivity maps spanning both Pine Island and Thwaites Glaciers. Relative reflectivities range from -24.8 to +37.4 dB with the highest values beneath fast-flowing ice at the ice sheet margin. By comparing our reflectivity results with previously derived radar specularity and trailing bed echoes at Thwaites Glacier, we find a highly diverse subglacial landscape and hydrologic condition that evolve along flow. Together, these findings highlight the potential for joint airborne radar analysis with ground-based seismic and geomorphological observations to understand variations in the bed properties and cross-catchment interactions of ice streams and outlet glaciers

Very High Resolution (VHR) Satellite Imagery: Processing and Applications

Recently, growing interest in the use of remote sensing imagery has appeared to provide synoptic maps of water quality parameters in coastal and inner water ecosystems;, monitoring of complex land ecosystems for biodiversity conservation; precision agriculture for the management of soils, crops, and pests; urban planning; disaster monitoring, etc. However, for these maps to achieve their full potential, it is important to engage in periodic monitoring and analysis of multi-temporal changes. In this context, very high resolution (VHR) satellite-based optical, infrared, and radar imaging instruments provide reliable information to implement spatially-based conservation actions. Moreover, they enable observations of parameters of our environment at greater broader spatial and finer temporal scales than those allowed through field observation alone. In this sense, recent very high resolution satellite technologies and image processing algorithms present the opportunity to develop quantitative techniques that have the potential to improve upon traditional techniques in terms of cost, mapping fidelity, and objectivity. Typical applications include multi-temporal classification, recognition and tracking of specific patterns, multisensor data fusion, analysis of land/marine ecosystem processes and environment monitoring, etc. This book aims to collect new developments, methodologies, and applications of very high resolution satellite data for remote sensing. The works selected provide to the research community the most recent advances on all aspects of VHR satellite remote sensing