cscheid.net
some papers, some blog posts, some code. like nowhere else on the web.
High-Quality Extraction of Isosurfaces from Regular and Irregular Grids
John Schreiner, Carlos Scheidegger, Claudio T. Silva. IEEE TVCG, 12(5):1205-1212 (IEEE Vis 2006).
We propose a new advancing front technique that is capable of creating high-quality isosurfaces from regular and irregular volumetric datasets. Our work extends the guidance field framework of Schreiner et al. to implicit surfaces, and improves it in significant ways. In particular, we describe a set of sampling conditions that guarantee that surface features will be captured by the algorithm. We also describe an efficient technique to compute a minimal guidance field, which greatly improves performance. Our experimental results show that our technique can generate high-quality meshes from complex datasets.
Managing the Evolution of Dataflows with VisTrails
Steven P. Callahan, Juliana Freire, Emanuele Santos, Carlos Scheidegger, Claudio T. Silva, Huy T. Vo. SciFlow 2006.
Extended abstract. VisTrails provides a scientific workflow infrastructure which can be combined with existing visualization systems and libraries. A key feature that sets VisTrails apart from previous visualization as well as scientific workflow systems is the support for data exploration. By maintaining detailed provenance of the exploration process — both within and across different versions of a dataflow — it allows scientists to easily navigate through the space of dataflows created for a given exploration task.
Direct (Re)Meshing for Efficient Surface Processing
John Schreiner, Carlos Scheidegger, Shachar Fleishman, Claudio Silva. Computer Graphics Forum, 25(3):527-536, (Eurographics 2006).
We propose a novel surface remeshing algorithm. While many remeshing algorithms are based on global parametrization or local mesh optimization, our algorithm is closely related to surface reconstruction techniques and it requires no explicit parameterization. Our approach is based on the advancing-front paradigm, and it can be used to both incrementally remesh the complete surface, or simply to remesh a portion of it with a high-quality mesh. It is accurate, fast, robust, and suitable for use with interactive mesh processing applications that require local remeshing. We show a number of applications, including matching the resolution of meshes when doing Boolean operations such as unions and intersections. We also show how to adapt the algorithm to blend and merge mixed-mode objects, and, for example, to compute the union of a point-set surface and a triangle mesh.
Practical CFD Simulations on Programmable Graphics Hardware using SMAC
Carlos Scheidegger, Joao L. D. Comba, Rudnei D. da Cunha. Computer Graphics Forum, 24(4):715–728, 2005.
We show how to harness the computational power of GPUs and solve the incompressible Navier-Stokes fluid equations significantly faster (more than one order of magnitude in average) than on CPU solvers of comparable cost.
VisTrails: Enabling Interactive Multiple-View Visualizations
Louis Bavoil, Steven P. Callahan, Patricia J. Crossno, Juliana Freire, Carlos Scheidegger Claudio Silva, Huy Vo. IEEE Vis 2005.
VisTrails is a new system that enables interactive multiple-view visualizations by simplifying the creation and maintenance of visualization pipelines, and by optimizing their execution. It provides a general infrastructure that can be combined with existing visualization systems and libraries. A key component of VisTrails is the visualization trail (vistrail), a formal specification of a pipeline. Unlike existing dataflow-based systems, in VisTrails there is a clear separation between the specification of a pipeline and its execution instances. This separation enables powerful scripting capabilities and provides a scalable mechanism for generating a large number of visualizations. VisTrails also leverages the vistrail specification to identify and avoid redundant operations. This optimization is especially useful while exploring multiple visualizations. When variations of the same pipeline need to be executed, substantial speedups can be obtained by caching the results of overlapping subsequences of the pipelines. In this paper, we describe the design and implementation of VisTrails, and show its effectiveness in different application scenarios.
Triangulating Point-Set Surfaces With Bounded Error
Carlos Scheidegger, Shachar Fleishman, Claudio T. Silva. SGP 2005.
We introduce an algorithm for constructing a high-quality triangulation directly from Point Set Surfaces. Our algorithm requires no intermediate representation and no post-processing of the output, and naturally handles noisy input data, typically in the form of a set of registered range scans. It creates a triangulation where triangle size respects the geometry of the surface rather than the sampling density of the range scans. Our technique does not require normal information, but still produces a consistent orientation of the triangles, assuming the sampled surface is an orientable two-manifold. Our work is based on using Moving Least-Squares (MLS) surfaces as the underlying representation. Our technique is a novel advancing front algorithm, that bounds the Hausdorff distance to within a user-specified limit. Specifically, we introduce a way of augmenting advancing front algorithms with global information, so that triangle size adapts gracefully even when there are large changes in surface curvature. Our results show that our technique generates high-quality triangulations where other techniques fail to reconstruct the correct surface due to irregular sampling on the point cloud, noise, registration artifacts, and underlying geometric features, such as regions with high curvature gradients.
VisTrails
VisTrails is a new visualization system whose goal is to provide scientists with an infrastructure that helps the exploration process inherent in developing effective visualizations. VisTrails emphasizes the importance of process provenance: it transparently keeps track of the visualizations as they are created. This facilitates exploration and reproducibility; users can always very easily go back to previous results. VisTrails was originally created for scientific visualization, but its infrastructure is equally well-suited for more general computational tasks - in particular those involving multiple separate libraries.
About me
I'm a researcher at AT&T Labs–Research, in the Information Visualization group. I work in data visualization, geometry processing and computer graphics. Opinions here are all mine.