Papers by David H. Laidlaw
Designer-critiqued Comparison of 2D Vector
IntroductionEvaluation of scientific visualization methods is typically eitheranecdotal, with fee... more IntroductionEvaluation of scientific visualization methods is typically eitheranecdotal, with feedback from scientific users, or quantitative, with performance measured on simple abstract tasks performed byrelatively nave users. While scientific users can provide domainspecificfeedback, neither population is typically trained toprovide visual-design feedback. The current pilot study examines how expert graphic designknowledge can provide a fast and robust visualization evaluationmethodology, one that assesses ...
White matter changes with age utilizing quantitative diffusion MRI
Neurology, Jan 15, 2014
To investigate the relationship between older age and mean cerebral white matter fiber bundle len... more To investigate the relationship between older age and mean cerebral white matter fiber bundle lengths (FBLs) in specific white matter tracts in the brain using quantified diffusion MRI. Sixty-three healthy adults older than 50 years underwent diffusion tensor imaging. Tractography tracings of cerebral white matter fiber bundles were derived from the diffusion tensor imaging data. Results revealed significantly shorter FBLs in the anterior thalamic radiation for every 1-year increase over the age of 50 years. We investigated the effects of age on FBL in specific white matter tracts in the brains of healthy older individuals utilizing quantified diffusion MRI. The results revealed a significant inverse relationship between age and FBL. Longitudinal studies of FBL across a lifespan are needed to examine the specific changes to the integrity of white matter.
Abstract CavePainting is an artistic medium that uses a 3D analog of 2D brush strokes to create 3... more Abstract CavePainting is an artistic medium that uses a 3D analog of 2D brush strokes to create 3D works of art in a fully immersive Cave environment. Physical props and gestures are used to provide an intuitive interface for artists who may not be familiar with virtual reality. The system is designed to take advantage of the 8 ft. x 8 ft. x 8 ft. space in which the artist works. CavePainting enables the artist to create a new type of art and provides a novel approach to viewing this art after it has been created.
Introduction �� We evaluated automated tractography clustering results via expert characterizatio... more Introduction �� We evaluated automated tractography clustering results via expert characterization of white-matter features present in the clustering results, in the tractography results, and in the normal brain.. The results show that automated clustering algorithms can identify fiber clusters that correlate with known white matter anatomy and that preserve most features in tractography results. Improvements in data acquisition, tractography, and clustering algorithms have the potential to improve the results.
Abstract The evolution of computational science over the last decade has resulted in a dramatic i... more Abstract The evolution of computational science over the last decade has resulted in a dramatic increase in raw problem solving capabilities. This growth has given rise to advances in scientific and engineering simulations that have put a high demand on tools for high-performance large-scale data exploration and analysis. These simulations have the potential to generate large amounts of data.
This article provides a snapshot of immersive virtual reality (IVR) use for scientific visualizat... more This article provides a snapshot of immersive virtual reality (IVR) use for scientific visualization, in the context of the evolution of computing in general and of user interfaces in particular. The main thesis of this article is that IVR has great potential for dealing with the serious problem of exponentially growing scientific datasets. Our ability to produce large datasets both through numerical simulation and through data acquisition via sensors is outrunning our ability to make sense of those datasets.
In vivo cytometry of antigen���specific t cells using 19F MRI
Abstract Noninvasive methods to image the trafficking of phenotypically defined immune cells are ... more Abstract Noninvasive methods to image the trafficking of phenotypically defined immune cells are paramount as we attempt to understand adaptive immunity. A 19 F MRI-based methodology for tracking and quantifying cells of a defined phenotype is presented. These methods were applied to a murine inflammation model using antigen-specific T cells.
Abstract We present an application of a virtual reality (VR) tool to the problem of creating scie... more Abstract We present an application of a virtual reality (VR) tool to the problem of creating scientific visualizations in VR. Our tool allows a designer to prototype a visualization prior to implementation. The system evolved from CavePainting [Keefe et al. 2001], which allows artists to draw in VR. We introduce the concept of using an interactive legend to link a visualization design to the visualization data.
Abstract Orthopedists invest significant amounts of effort and time trying to understand the biom... more Abstract Orthopedists invest significant amounts of effort and time trying to understand the biomechanics of arthrodial (gliding) joints. Although new image acquisition and processing methods currently generate richer-than-ever geometry and kinematic data sets that are individual specific, the computational and visualization tools needed to enable the comparative analysis and exploration of these data sets lag behind.
Abstract Here, the authors combine a pure phase-encoded magnetic resonance imaging (MRI) method w... more Abstract Here, the authors combine a pure phase-encoded magnetic resonance imaging (MRI) method with a new tissue-classification technique to make geometric models of a human tooth. They demonstrate the feasibility of three-dimensional imaging of solids using a conventional 11.7-T NMR spectrometer. In solid-state imaging, confounding line-broadening effects are typically eliminated using coherent averaging methods.
Abstract We present an application of uncertainty visualization to air parcel trajectories genera... more Abstract We present an application of uncertainty visualization to air parcel trajectories generated from a global meteorological model. We derive an approximation of advection uncertainty due to interpolation and incorporate this uncertainty into our visualization of trajectories. Our work enables efficient visual pruning of unlikely results, especially in regions of atmospheric shear, potentially reducing erroneous interpretations. Finally, we apply these methods to a real-world meteorological problem to demonstrate its use.
Abstract A three-dimensional model with simplified geometry for the coronary artery is presented.... more Abstract A three-dimensional model with simplified geometry for the coronary artery is presented. In particular, both bifurcation and multi-planar curvature are included in the geometry of the computational domain. The model takes into account the repetitive variation of curvature and motion to which the vessel is subject during each cardiac cycle. It also accounts for the phase difference between arterial motion and flowrate that may be nonzero for patients with aortic regurgitation.
There are two unusual aspects to the approach. First, it uses the assumption that, due to partial... more There are two unusual aspects to the approach. First, it uses the assumption that, due to partialvolume effects, or blurring, voxels can contain more than one material, eg, both muscle and fat; it computes the relative proportion of each material in the voxels. Second, the approach incorporates information from neighboring voxels into the classification process by reconstructing a continuous function, x, from the samples and then looking at the distribution of values that x takes on within the region of a voxel.
Abstract We present a method for refining clusters of 3D curves using a new coherence measure. Cu... more Abstract We present a method for refining clusters of 3D curves using a new coherence measure. Curves are common geometric models used for representing the information derived from different types of data, in particular scientific data represented as vector and tensor fields. Our method starts with an initial set of clusters. For each cluster, we probe samples from the cluster by ���slicing��� it with a plane at regularly spaced locations parameterized by curve arclengths.
Water diffusion is anisotropic in organized tissues such as white matter and muscle. Diffusion te... more Water diffusion is anisotropic in organized tissues such as white matter and muscle. Diffusion tensor imaging (DTI), a non-invasive MR technique, measures water self-diffusion rates and thus gives an indication of the underlying tissue microstructure. The diffusion rate is often expressed by a second-order tensor. Insightful DTI visualization is challenging because of the multivariate nature and the complex spatial relationships in a diffusion tensor field.
Abstract. We present an analytical water diffusion model for inferring important microstructural ... more Abstract. We present an analytical water diffusion model for inferring important microstructural properties such as axon radius, orientation, and packing density using low-q angular Double Pulsed Gradient Spin Echo (double-PGSE) NMR, taking into account finite gradient pulses. The MR signal attenuation obtained from Single Pulsed Gradient Spin Echo (single-PGSE) NMR reflects the underlying microstructural properties that restrict the molecular diffusion within.
Abstract We present a visual exploration paradigm that facilitates navigation through complex fib... more Abstract We present a visual exploration paradigm that facilitates navigation through complex fiber tracts by combining traditional 3D model viewing with lower dimensional representations. To this end, we create standard streamtube models along with two two-dimensional representations, an embedding in the plane and a hierarchical clustering tree, for a given set of fiber tracts. We then link these three representations using both interaction and color obtained by embedding fiber tracts into a perceptually uniform color space.
We present a technique for visualizing the differences between two Diffusion Tensor Magnetic Reso... more We present a technique for visualizing the differences between two Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) volumes. Our technique registers two DT-MRIs and then produces a 3D model that allows a user to simultaneously view structure in both volumes. The geometric model is based on one developed to visually represent a single volume with a carefully chosen set of streamtubes [6, 7]. In the new model, we choose corresponding tubes from both volumes and show how they differ.
Abstract From 19.07. to 24.07. 2009, the Dagstuhl Seminar 09302``New Developments in the Visualiz... more Abstract From 19.07. to 24.07. 2009, the Dagstuhl Seminar 09302``New Developments in the Visualization and Processing of Tensor Fields''was held in Schloss Dagstuhl~--~ Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper.
Abstract We present an immersive system for exploring numerically simulated flow data through a m... more Abstract We present an immersive system for exploring numerically simulated flow data through a model of a coronary artery graft. This tightly-coupled interdisciplinary project is aimed at understanding how to reduce the failure rate of these grafts. The visualization system provides a mechanism for exploring the effect of changes to the geometry, to the flow, and for exploring potential sources of future lesions.
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Papers by David H. Laidlaw