Tony Bernardin

Late Cenozoic deformation of the Kura fold-thrust belt, southern Greater Caucasus

Although the geometry and kinematics of the first-order structures accommodating Arabia-Eurasia convergence are relatively well known in Turkey and Iran, major shortening structures remain poorly understood within the central portion of the collision zone, in eastern Anatolia and the Caucasus. New remotely sensed neotectonic mapping, synthesis of regional geologic and stratigraphic data, and balanced cross sections suggest that the Kura fold-thrust belt has accommodated the majority of Arabia-Eurasia convergence since the early Pliocene between the longitudes of ∼45°E and ∼49°E. This belt lies southeast of the N80°W-striking Greater Caucasus Mountains and forms an eastward-narrowing band of elevated topography that roughly parallels the range front for ∼400 km along strike. The belt is separated from the Greater Caucasus to the north by the 10- to 25-km-wide Alazani Basin and comprises a series of predominantly south-verging folds deforming Eocene–Quaternary flysch and molasse. To document structural geometries within the Kura fold-thrust belt, we have used the Real-time Interactive Mapping System (RIMS) software to analyze Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), visible to near-infrared (VNIR), and digital elevation model (DEM) data. This neotectonic mapping indicates an along-strike, eastward decrease in both structural complexity and the degree to which deformed geomorphic surfaces are dissected. Existing geologic maps indicate a corresponding eastward decrease in the depth of exposure. By integrating the structural geometries determined in our analysis of remote-sensing data with existing geologic data, we have constructed two balanced cross sections, which suggest these systematic along-strike variations result from a west-to-east decrease in total shortening within the Kura fold-thrust belt. We interpret this variable shortening to stem from eastward propagation of the Kura fold-thrust belt. Comparison of our preliminary total shortening estimates with those predicted by current plate motions suggest that the Kura fold-thrust belt has accommodated ∼30%–40% (∼25 km) of total Arabia-Eurasia convergence since 5 Ma, and thus forms a first-order structural system within the central portion of the collision zone.

Out-of-core Data Management for Path Tracing on Hybrid Resources

We present a software system that enables path‐traced rendering of complex scenes. The system consists of two primary components: an application layer that implements the basic rendering algorithm, and an out‐of‐core scheduling and data‐management layer designed to assist the application layer in exploiting hybrid computational resources (e.g., CPUs and GPUs) simultaneously. We describe the basic system architecture, discuss design decisions of the systems data‐management layer, and outline an efficient implementation of a path tracer application, where GPUs perform functions such as ray tracing, shadow tracing, importance‐driven light sampling, and surface shading. The use of GPUs speeds up the runtime of these components by factors ranging from two to twenty, resulting in a substantial overall increase in rendering speed. The path tracer scales well with respect to CPUs, GPUs and memory per node as well as scaling with the number of nodes. The result is a system that can render large complex scenes with strong performance and scalability.

Enabling scientific workflows in virtual reality

To advance research and improve the scientific return on data collection and interpretation efforts in the geosciences, we have developed methods of interactive visualization, with a special focus on immersive virtual reality (VR) environments. Earth sciences employ a strongly visual approach to the measurement and analysis of geologic data due to the spatial and temporal scales over which such data ranges. As observations and simulations increase in size and complexity, the Earth sciences are challenged to manage and interpret increasing amounts of data. Reaping the full intellectual benefits of immersive VR requires us to tailor exploratory approaches to scientific problems. These applications build on the visualization methods strengths, using both 3D perception and interaction with data and models, to take advantage of the skills and training of the geological scientists exploring their data in the VR environment. This interactive approach has enabled us to develop a suite of tools that are adaptable to a range of problems in the geosciences and beyond.

High-Quality Visualization for Geographically Distributed 3-D Teleimmersive Applications

The growing popularity of 3-D movies has led to the rapid development of numerous affordable consumer 3-D displays. In contrast, the development of technology to generate 3-D content has lagged behind considerably. In spite of significant improvements to the quality of imaging devices, the accuracy of the algorithms that generate 3-D data, and the hardware available to render such data, the algorithms available to calibrate, reconstruct, and then visualize such data remain difficult to use, extremely noise sensitive, and unreasonably slow. In this paper, we present a multi-camera system that creates a highly accurate (on the order of a centimeter), 3-D reconstruction of an environment in real-time (under 30 ms) that allows for remote interaction between users. This paper focuses on addressing the aforementioned deficiencies by describing algorithms to calibrate, reconstruct, and render objects in the system. We demonstrate the accuracy and speed of our results on a variety of benchmarks and data collected from our own system.

Interactive terrain visualization enables virtual field work during rapid scientific response to the 2010 Haiti earthquake

The moment magnitude (Mw) 7.0 12 January 2010 Haiti earthquake is the fi rst major earthquake for which a large-footprint LiDAR (light detection and ranging) survey was acquired within several weeks of the event. Here, we describe the use of virtual reality data visualization to analyze massive amounts (67 GB on disk) of multiresolution terrain data during the rapid scientifi c response to a major natural disaster. In particular, we describe a method for conducting virtual fi eld work using both desktop computers and a 4-sided, 22 m 3 CAVE immersive virtual reality environment, along with KeckCAVES (Keck Center for Active Visualization in the Earth Sciences) software tools LiDAR Viewer, to analyze LiDAR pointcloud data, and Crusta, for 2.5 dimensional surfi cial geologic mapping on a bare-earth digital elevation model. This system enabled virtual fi eld work that yielded remote observations of the topographic expression of active faulting within an ~75-km-long section of the eastern Enriquillo‐Plantain Garden fault spanning the 2010 epicenter. Virtual fi eld observations indicated that the geomorphic evidence of active faulting and ancient surface rupture varies along strike. Landform offsets of 6‐50 m along the Enriquillo‐ Plantain Garden fault east of the 2010 epicenter and closest to Port-au-Prince attest to repeated recent surface-rupturing earthquakes there. In the west, the fault trace is well defi ned by displaced landforms, but it is not as clear as in the east. The 2010 epi center is within a transition zone between these sections that extends from Grand Goâve in the west to Fayette in the east. Within this transition, between L’Acul (lat 72°40′W) and the Rouillone River (lat 72°35′W), the Enriquillo‐Plantain Garden fault is un defi ned along an embayed low-relief range front, with little evidence of recent surface rupture. Based on the geometry of the eastern and western faults that show evidence of recent surface rupture, we propose that the 2010 event occurred within a stepover that appears to have served as a long-lived boundary between rupture segments, explaining the lack of 2010 surface rupture. This study demonstrates how virtual reality‐based data visualization has the potential to transform rapid scientifi c response by enabling virtual fi eld studies and real-time interactive analysis of massive terrain data sets.

A methodology for remote virtual interaction in teleimmersive environments

Though the quality of imaging devices, the accuracy of algorithms that construct 3D data, and the hardware available to render such data have all improved, the algorithms available to calibrate, reconstruct, and then visualize such data are difficult to use, extremely noise sensitive, and unreasonably slow. In this paper, we describe a multi-camera system that creates a highly accurate (on the order of a centimeter), 3D reconstruction of an environment in real time (under 30 ms) that allows for remote interaction between users. The paper addresses the aforementioned deficiencies by featuring an overview of the technology and algorithms used to calibrate, reconstruct, and render objects in the system. The algorithm produces partial 3D meshes, instead of dense point clouds, which are combined on the renderer to create a unified model of the environment. The chosen representation of the data allows for high compression ratios for transfer to remote sites. We demonstrate the accuracy and speed of our results on a variety of benchmarks and data collected from our own system.

Interactive mapping on 3‐D terrain models

We present an interactive, real-time mapping system for use with digital elevation models and remotely sensed multispectral imagery that aids geoscientists in the creation and interpretation of geologic/neotectonic maps at length scales of 10 m to 1000 km. Our system provides a terrain visualization of the surface of the Earth or other terrestrial planets by displaying a virtual terrain model generated from a digital elevation model overlain by a color texture generated from orthophotos or satellite imagery. We use a quadtree-based, multiresolution display method to render in real time high-resolution virtual terrain models that span large spatial regions. The system allows users to measure the orientations of geologic surfaces and record their observations by drawing lines directly on the virtual terrain model. In addition, interpretive surfaces can be generated from these drawings and displayed to facilitate understanding of the three-dimensional geometry of geologic surfaces. The main strength of our system is the combination of real-time rendering and interactive mapping performed directly on the virtual terrain model with the ability to navigate the scene while changing viewpoints arbitrarily during mapping. User studies and comparisons with commercially available mapping software show that our system improves mapping accuracy and efficiency and also yields observations that cannot be made with existing systems.

Real-time Terrain Mapping

We present an interactive, real-time mapping system for digital elevation maps (DEMs), which allows Earth scientists to map and therefore understand the deformation of the continental crust at length scales of 10m to 1000km. Our system visualizes the surface of the Earth as a 3D surface generated from a DEM, with a color texture generated from a registered multispectral image and vector-based mapping elements draped over it. We use a quadtree-based multiresolution method to be able to render high-resolution terrain mapping data sets of large spatial regions in real time. The main strength of our system is the combination of interactive rendering and interactive mapping directly onto the 3D surface, with the ability to navigate the terrain and to change viewpoints arbitrarily during mapping. User studies and comparisons with commercially available mapping software show that our system improves mapping accuracy and eciency, and also enables qualitatively dierent observations that are not possible to make with existing systems.

Stacked-widget visualization of scheduling-based algorithms

We present a visualization system to assist designers of scheduling-based multi-threaded out-of-core algorithms. Our system facilitates the understanding and improving of the algorithm through a stack of visual widgets that effectively correlate the out-of-core system state with scheduling decisions. The stack presents an increasing refinement in the scope of both time and abstraction level; at the top of the stack, the evolution of a derived efficiency measure is shown for the scope of the entire out-of-core system execution and at the bottom the details of a single scheduling decision are displayed. The stack provides much more than a temporal zoom-effect as each widget presents a different view of the scheduling decision data, presenting distinct aspects of the out-of-core system state as well as correlating them with the neighboring widgets in the stack. This approach allows designers to to better understand and more effectively react to problems in scheduling or algorithm design. As a case study we consider a global illumination renderer and show how visualization of the scheduling behavior has led to key improvements of the renderers performance.

Managing a document-based information space

We present a novel user interface in the form of a complementary virtual environment for managing personal document archives, i.e., for document filing and retrieval. Our implementation of a spatial medium for document interaction, exploratory search and active navigation plays to the strengths of human visual information processing and further stimulates it. Our system provides a high degree of immersion so that the user readily forgets the artificiality of our environment. Three well-integrated features support this immersion: first, we enable users to interact more naturally through gestures and postures (the system can be taught custom ones); second, we exploit 3D display technology; and third, we allow users to manage arrangements (manually edited structures, as well as computer-generated semantic structures). Our ongoing evaluation indicates that even non-expert users can efficiently work with the information in a document collection and that the process can actually be enjoyable.