Terrain

Abstract: This report documents our study of active balance in dynamic legged systems. The purpose of this research is to build a foundation of knowledge that can lead both to the construction of useful legged vehicles and to a better understanding of animal locomotion. ...

The Ground Penetrating Radar (GPR) method has been extensively used to map shallow subsurface features. Such kind of information is very important for different types of studies, ranging from archaeological to groundwater search. Almost all GPR surveys for groundwater exploration are usually conducted in sedimentary terrains. In this paper, we demonstrate the applicability of the GPR method in the exploration of underground water in a crystalline terrain. An example of fixed offset data collected at one known spring in the district of Petrópolis (Brazil) is given. Common Mid Point (CMP) data were also collected to estimate the velocity of the radar waves. The saturated region is clearly outlined in the GPR section as a zone of attenuation and inversion of the wavelet phase polarity.

Because the removal of topographic effects is one the most important pre-processing steps when extracting information from satellite images in digital Earth applications, the problem of differential terrain illumination on satellite imagery has been investigated for at least 20 years. As there is no superior topographic correction method applicable to all areas and all images, a comparison of topographic normalization methods in different regions and images is necessary. In this study, common topographic correction methods were applied on an ALOS AVNIR-2 image of a rugged forest area, and the results were evaluated through different criteria. The results show that the simple correction methods [Cosine, Sun-Canopy-sensor (SCS), and Minnaert correction] are inefficient in exceptionally rough forests. Among the improved correction methods (SCS+C, modified Minnaert, and pixel-based Minnaert), the best result was achieved using a pixel-based Minnaert approach in which a separate correction factor in various slope angles is used. Thus, this method should be considered for topographic correction, especially in forests with severe topography.

Triassic strata of the Dockum Group in Texas comprise two major upward-fining alluvial-lacustrine depositional sequences. The two sequences are represented by the (1) Santa Rosa-Tecovas, and (2) Trujillo-Cooper Canyon Formations. The second sequence is much thicker than the first, and occupies a greater geographic part of the Dockum basin. Each sequence of alluvial and lacustrine sediment accumulation is characterized by sediment derivation from a different source terrain. The unconformable relationship between the two depositional sequences, the change in mineralogical composition and presumed source areas between these units, differences in paleocurrent orientation between units, and evidence for intervening episodes of local deformation indicate that the sequences are of tectonic origin. These strata are not the product of a single sediment dispersal system, such as the centripetally-drained lacustrine delta complex previously envisioned for the Dockum basin. Both Dockum sequences are comprised largely of two typical alluvial facies associations; stream channel facies, and overbank flood-plain facies, that are similar to those described in nearly all fluvial deposits. In addition, the Dockum Group contains a peculiar lacustrine facies that accumulated in local flood-plain depressions, and probably resulted from subsidence over areas of subsurface salt dissolution. Vertebrate fossil assemblages are found in all three Dockum facies associations. Five fossiliferous sites in the Dockum are discussed in the context of these three depositional settings. The Dockum tetrapod diversity is reviewed in a hierarchical phylogeny with remarks on the history of collection, stratigraphic distribution of genera, and their taxonomic status. The stratigraphic ranges of tetrapod taxa do not support the recently proposed successive Otischalkian, Adamanian, Revueltian, and Apachean biochrons within the Dockum Group. Instead, a few index fossils provide a broad framework for correlation of Late Triassic nonmarine strata of the Dockum with the Carnian and Norian Alpine marine stages.

ABSTRACT Constructing the dolphin's mindComparisons are made of how the dolphin’s “mind” is “constructed” in six interactional contexts distinguished by the degree of participation (in the ethnological sense of the term) by human beings or even by the dolphins themselves: the study of the brain, the study of sensorial capabilities, research on cognition, naturalistic observations, communication among dolphins, and meetings on the high sea. On the basis of these comparisons, it is argued that whether or not people attribute a “mind” to the dolphin very much depends on the degree of likeness that they recognize with these animals, which, in turn, depends on the person’s capacity to let himself be “affected” by them.

Airborne laser scanning and image matching can today form the basis for the generation of digital terrain models (DTMs). In addition to the DTM, quality parameters are needed that describe the accuracy at a high level of detail, at best for every interpolated DTM point. Furthermore, other parameters are of interest, for example, the distance from each DTM point to the data point next to it. This paper presents a method to derive accuracy measures from the original data and the DTM itself. Its application is demonstrated with an example. The quality measures are suitable for informing users in detail about DTM quality and warning them of weakly determined areas.Pour établir des modèles numériques du terrain (MNT) on peut considérer qu'on dispose actuellement, comme techniques de base, du scannage par laser aéroporté et de l'appariement d'images. Accompagnant le MNT, il est souhaitable d'avoir en supplément des paramètres de qualité qui en fournissent la précision avec un grand niveau de détail, au moins en chacun des points du MNT obtenus par interpolation. D'autres paramètres sont également intéressants, comme par exemple la distance de chaque point du MNT au point de base voisin. On décrit dans cet article une méthode permettant de déterminer la précision à partir des données-source et du MNT lui-même. Un exemple vient en appui de cette méthode. La connaissance de la qualité d'un MNT est une information très utile pour les utilisateurs de ce MNT et qui les met en garde dans les zones où celui-ci présente des faiblesses dans sa formation.Flugzeuggetragenes Laserscanning und automatische Bildzuordnung dienen heutzutage als Grundlage für die Erstellung von digitalen Geländemodellen (DGM). Zusätzlich zum DGM werden Qualitätsparameter benötigt, die seine Genauigkeit sehr detailliert, am besten für jeden interpolierten DGM-Punkt, beschreiben. Außerdem sind weitere Parameter hilfreich, zum Beispiel die Distanz von jedem Gitterpunkt zum nächstgelegenen Datenpunkt. Dieser Artikel beschreibt eine Methode, um aus den Originaldaten und dem zu beurteilenden DGM seine Genauigkeit abzuleiten. Die Anwendung der Methode wird an einem Beispiel veranschaulicht. Mit Hilfe der präsentierten Qualitätsparameter können Benutzer sehr genau über die DGM-Qualität informiert und vor schlecht bestimmten Bereichen gewarnt werden.En la actualidad la altimetría de barrido láser y la correlación automática de imágenes son la base para la obtención de modelos digitales de elevación (MDE). Además del MDE, se necesitan parámetros de calidad que describan detalladamente su exactitud, a ser posible en cada punto interpolado del MDE. Además, hay otros parámetros de interés, por ejemplo la distancia entre cada punto del modelo y el punto original más próximo. Este artículo describe un método para obtener medidas de calidad de los datos originales y del propio MDE. Su aplicación se demuestra con un ejemplo. Mediante dichos parámetros de calidad se puede informar a los usuarios acerca de la calidad del MDE y advertirles acerca de las áreas peor estimadas.

The ability to perform off-road autonomous navigation at any time of day or night is a requirement for some unmanned ground vehicle (UGV) programs. Because there are times when it is desirable for military UGVs to operate without emitting strong, detectable electromagnetic signals, a passive only terrain perception mode of operation is also often a requirement. Thermal infrared (TIR) cameras can be used to provide day and night passive terrain perception. TIR cameras have a detector sensitive to either mid-wave infrared (MWIR) radiation (3-5μm) or long-wave infrared (LWIR) radiation (7-14μm). With the recent emergence of high-quality uncooled LWIR cameras, TIR cameras have become viable passive perception options for some UGV programs. The Jet Propulsion Laboratory (JPL) has used a stereo pair of TIR cameras under several UGV programs to perform stereo ranging, terrain mapping, tree-trunk detection, pedestrian detection, negative obstacle detection, and water detection based on object reflections. In addition, we have evaluated stereo range data at a variety of UGV speeds, evaluated dual-band TIR classification of soil, vegetation, and rock terrain types, analyzed 24 hour water and 12 hour mud TIR imagery, and analyzed TIR imagery for hazard detection through smoke. Since TIR cameras do not currently provide the resolution available from megapixel color cameras, a UGV's daytime safe speed is often reduced when using TIR instead of color cameras. In this paper, we summarize the UGV terrain perception work JPL has performed with TIR cameras over the last decade and describe a calibration target developed by General Dynamics Robotic Systems (GDRS) for TIR cameras and other sensors.