TY - JOUR A1 - Böniger, Urs A1 - Tronicke, Jens T1 - Subsurface utility extraction and characterization combining GPR symmetry and polarization attributes JF - IEEE transactions on geoscience and remote sensing N2 - Polarization of the electromagnetic wavefield has significant implications for the acquisition and interpretation of ground-penetrating radar (GPR) data. Based on the geometrical and physical properties of the subsurface scatterer and the physical properties of its surrounding material, strong polarization phenomena might occur. Here, we develop an attribute-based analysis approach to extract and characterize buried utility pipes using two broadside antenna configurations. First, we enhance and extract the utilities by making use of their distinct symmetric nature through the application of a symmetry-enhancing image-processing algorithm known as phase symmetry. Second, we assess the polarization characteristics by calculating two attributes (polarization angle and linearity) using principal component analysis. Combination of attributes derived from these steps into a novel depolarization attribute allows one to efficiently detect and distinguish different utilities present within 3-D GPR data. The performance of our analysis approach is illustrated using synthetic examples and evaluated using field examples (including a dual-configuration 3-D data set) collected across a field site, where detailed ground-truth information is available. Our results demonstrate that the proposed approach allows for a more detailed extraction and combination of utility relevant information compared to approaches relying on single-component data and, thus, eases the interpretation of multicomponent GPR data sets. KW - Multicomponent ground-penetrating radar (GPR) data KW - phase symmetry KW - pipe detection KW - polarization analysis KW - principal component analysis (PCA) Y1 - 2012 U6 - https://doi.org/10.1109/TGRS.2011.2163413 SN - 0196-2892 SN - 1558-0644 VL - 50 IS - 3 SP - 736 EP - 746 PB - Inst. of Electr. and Electronics Engineers CY - Piscataway ER - TY - JOUR A1 - Allroggen, Niklas A1 - Tronicke, Jens A1 - Delock, Marcel A1 - Böniger, Urs T1 - Topographic migration of 2D and 3D ground-penetrating radar data considering variable velocities JF - Near surface geophysics N2 - We present a 2D/3D topographic migration scheme for ground-penetrating radar (GPR) data which is able to account for variable velocities by using the root mean square (rms) velocity approximation. We test our migration scheme using a synthetic 2D example and compare our migrated image to the results obtained using common GPR migration approaches. Furthermore, we apply it to 2D and 3D field data. These examples are recorded across common subsurface settings including surface topography and variations in the GPR subsurface velocity field caused by a shallow ground water table. In such field settings, our migration strategy provides well focused images of commonoffset GPR data without the need for a detailed interval velocity model. The synthetic and field examples demonstrate that our topographic migration scheme allows for accurate GPR imaging in the presence of variations in surface topography and subsurface velocity. Y1 - 2015 U6 - https://doi.org/10.3997/1873-0604.2014037 SN - 1569-4445 SN - 1873-0604 VL - 13 IS - 3 PB - European Association of Geoscientists & Engineers CY - Houten ER - TY - JOUR A1 - Rumpf, M. A1 - Böniger, Urs A1 - Tronicke, Jens T1 - Refraction seismics to investigate a creeping hillslope in the Austrian Alps JF - ENGINEERING GEOLOGY N2 - Assessing the human and economic threat introduced by sliding or creeping masses is of major importance in landslide hazard assessment and mitigation. Especially, in the densely populated alpine region unstable hillslopes represent a major hazard to men and infrastructure. Detailed knowledge, especially, of the dominant site-specific controlling factors such as subsurface architecture and geology is thereby key in assessing slope vulnerability. In order to quantify the geological variations at a creeping hillslope in the Austrian Alps, we have collected six 2D refraction seismic profiles. We propose using a layer-based inversion strategy to reconstruct P-wave velocity models from first arrival times. Considering the geological complexity at such sites, the selected inversion approach eases the interpretability of geological structures given intrinsic optimization for only a discrete, user-defined, number of layers. As the applied layer-based inversion approach fits our travel time data equally well as traditional smooth inversion approaches, it represents a feasible mean to summarize the structural complexity often present at such sites. Analysis of the inversion results illustrates that bedrock topography clearly deviates from a previously assumed planar surface and exhibits distinct variations across the slope extension. Bedrock topography additionally impacts the intermediate geological units and, thus, this information is critical for further analyses such as geomechanical modeling. (C) 2012 Elsevier B.V. All rights reserved. KW - Hillslope KW - Refraction seismics KW - Austrian Alps KW - Layer-based inversion Y1 - 2012 U6 - https://doi.org/10.1016/j.enggeo.2012.09.008 SN - 0013-7952 VL - 151 IS - 24 SP - 37 EP - 46 PB - ELSEVIER SCIENCE BV CY - AMSTERDAM ER - TY - JOUR A1 - Tronicke, Jens A1 - Paasche, Hendrik A1 - Böniger, Urs T1 - Crosshole traveltime tomography using particle swarm optimization a near-surface field example JF - Geophysics N2 - Particle swarm optimization (PSO) is a relatively new global optimization approach inspired by the social behavior of bird flocking and fish schooling. Although this approach has proven to provide excellent convergence rates in different optimization problems, it has seldom been applied to inverse geophysical problems. Until today, published geophysical applications mainly focus on finding an optimum solution for simple, 1D inverse problems. We have applied PSO-based optimization strategies to reconstruct 2D P-wave velocity fields from crosshole traveltime data sets. Our inversion strategy also includes generating and analyzing a representative ensemble of acceptable models, which allows us to appraise uncertainty and nonuniqueness issues. The potential of our strategy was tested on field data collected at a well-constrained test site in Horstwalde, Germany. At this field site, the shallow subsurface mainly consists of sand- and gravel-dominated glaciofluvial sediments, which, as known from several boreholes and other geophysical experiments, exhibit some well-defined layering at the scale of our crosshole seismic data. Thus, we have implemented a flexible, layer-based model parameterization, which, compared with standard cell-based parameterizations, allows for significantly reducing the number of unknown model parameters and for efficiently implementing a priori model constraints. Comparing the 2D velocity fields resulting from our PSO strategy to independent borehole and direct-push data illustrated the benefits of choosing an efficient global optimization approach. These include a straightforward and understandable appraisal of nonuniqueness issues as well as the possibility of an improved and also more objective interpretation. Y1 - 2012 U6 - https://doi.org/10.1190/GEO2010-0411.1 SN - 0016-8033 SN - 1942-2156 VL - 77 IS - 1 SP - R19 EP - R32 PB - Society of Exploration Geophysicists CY - Tulsa ER -