10 research outputs found
Application of Geometric Polarization to Invariance Properties in Bistatic Scattering
Bistatic polarimetric radars provide target properties which just one monostatic system can not reveal. Moreover, augmentation of monostatic systems through the provision of bistatic receive-only stations can be a cheap way to increase the amount of remote sensing data. However, bistatic scattering needs to be investigated in order to properly define target properties such as symmetries and invariance, especially regarding choices of polarization basis. In this paper we discuss how the geometric theory of polarization, in which the geometry of the Poincaré sphere is directly related to 3-D geometry of space rather than the 2-D geometry of the wavefront plane, can be used to reduce the ambiguities in the interpretation of data. We also show how in the coherent case a complex scalar invariant can be determined irrespective of the basis combinations
The road surveying system of the federal highway research institute – a performance evaluation of road segmentation algorithms
The construction of highways and federal roadways is subject to many
restrictions and designing rules. The focus is on safety, comfort and smooth
driving. Unfortunately, the planning information for roadways and their real
constitution, course and their number of lanes and lane widths is often
unsure or not available. Due to digital map databases of roads raised much
interest during the last years and became one major cornerstone of innovative
Advanced Driving Assistance Systems (ADASs), the demand for accurate and
detailed road information increases considerably. Within this project a
measurement system for collecting high accurate road data was developed. This
paper gives an overview about the sensor configuration within the measurement
vehicle, introduces the implemented algorithms and shows some applications
implemented in the post processing platform. The aim is to recover the origin
parametric description of the roadway and the performance of the measurement
system is being evaluated against several original road construction
information
TOF-LIDAR signal processing using the CFAR detector
In recent years, the lidar sensor has been receiving greater attention as being one of the
prospective sensors for future intelligent vehicles. In order to enable
advanced applications in a variety of road environments, it has become more
important to detect various objects at a wider distance. Therefore, in this
research we have focused on lidar signal processing to detect low signal-to-noise ratio (SNR)
targets
and proposed a higher sensitive detector. The detector is based on the constant false alarm rate (CFAR)
processing framework in which an additional functionality of adaptive intensity
integration is incorporated. Fundamental results through static experiments
have shown a significant advantage in the detection performance in comparison
to a conventional detector with constant thresholding
Geometrical representation of a monochromatic electromagnetic wave using the tangential vector approach
The aim of this work is to develop a coherent polarimetric model and to find a geometrical description of a monochromatic wave. The spinor form of the electrical field, its links to the coherency matrix and the Poincare' sphere are introduced with the aim to obtain a geometrical representation of the spinor. It consists, from the "polarization point of view", on the polarization vector and a tangential plane to the Poincare' sphere where it is possible to visualize the zero phase
Local Dynamic Map als modulares Software Framework für Fahrerassistenzsysteme: Local Dynamic Map als modulares Software Framework fürFahrerassistenzsysteme
Moderne Fahrerassistenzsysteme basieren auf der Verarbeitung von Informationen, welche durch die Umfeldwahrnehmung mit unterschiedlicher Sensorik erfolgt. Neben den Informationen aus dem eigenen Fahrzeug ergeben sich durch unterschiedliche Kommunikationsmöglichkeiten (Car2Car, Car2X, ...) erweiterte Umfeldwahrnehmungen (siehe Abb. 1). Diese Daten gilt es aufbereitet und zielorientiert einer Anwendung zur Verfügung zu stellen, was mit Hilfe einer Local Dynamic Map (LDM) erfüllt werden kann. Die vorliegende Veröffentlichung beschreibt den Aufbau, Verwendungszweck und Eigenschaften einer entwickelten LDM und geht auf einige Applikationen ein, die mit Hilfe dieser realisiert wurden
Multi-view point cloud fusion for LiDAR based cooperative environment detection
A key component for automated driving is 360° environment detection.
The recognition capabilities of modern sensors are always limited to their
direct field of view. In urban areas a lot of objects occlude important areas
of interest. The information captured by another sensor from another
perspective could solve such occluded situations. Furthermore, the
capabilities to detect and classify various objects in the surrounding can be
improved by taking multiple views into account.
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In order to combine the data of two sensors into one coordinate system, a
rigid transformation matrix has to be derived. The accuracy of modern e.g.
satellite based relative pose estimation systems is not sufficient to
guarantee a suitable alignment. Therefore, a registration based approach is
used in this work which aligns the captured environment data of two sensors
from different positions. Thus their relative pose estimation obtained by
traditional methods is improved and the data can be fused.
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To support this we present an approach which utilizes the uncertainty
information of modern tracking systems to determine the possible field of
view of the other sensor. Furthermore, it is estimated which parts of the
captured data is directly visible to both, taking occlusion and shadowing
effects into account. Afterwards a registration method, based on the
iterative closest point (ICP) algorithm, is applied to that data in order to
get an accurate alignment.
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The contribution of the presented approch to the achievable accuracy is shown
with the help of ground truth data from a LiDAR simulation within a 3-D
crossroad model. Results show that a two dimensional position and heading
estimation is sufficient to initialize a successful 3-D registration process.
Furthermore it is shown which initial spatial alignment is necessary to
obtain suitable registration results
Improving pedestrian detection using MPEG-7 descriptors
During the last decade, modern Pedestrian Detection Systems made massive use
of the steadily growing numbers of high-performance image acquisition
sensors. Within our naturalistic driving environment, a lot of different and
heterogeneous scenes occur that are caused by varying illumination and
weather conditions. Unfortunately, current systems do not work properly under
these hardened conditions. The aim of this article is to investigate and
evaluate observed video scenes from an open source dataset by using various
image features in order to create a basis for robust and more accurate object
detection
Potential of coherent decompositions in SAR polarimetry and interferometry
A comparative study has indicated that coherent decompositions may have high potential in applications using fully polarimetric and interferometric SAR data, as an alternative or supplement to standard non-coherent techniques developed during the last decade. One important reason for this is that the coherent techniques are better able to benefit from the coherent nature of the underlying data and scattering mechanisms. By avoiding averaging at the first processing stage, the coherent techniques can extract target features that may otherwise be lost in the early averaging process. On the other hand, averaging is indeed important in most cases for obtaining stable and reliable end results
Automatisierter Strassenverkehr. Teilvorhaben: Kolonnenfahrt und Durchsatzoptimierung im Strassenverkehr (Elektronisches Auge - AVDB). Phase 1 Abschlussbericht
Available from TIB Hannover: F98B1971+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman