Ma, KL
1996
Efficient Streamline, Streamribbon, and Streamtube Constructions on Unstructured Grids
Ueng, S.-K.; Sikorski, K. and Ma, K.-L.
IEEE Transactions on Visualization and Computer Graphics, 2(2):100-108, 1996. Partially funded by ACERC.
Streamline construction is one of the most fundamental techniques for visualizing steady flow fields. Streamribbons and streamtubes are extensions for visualizing the rotation and the expansion of the flow. This paper presents efficient algorithms for constructing streamlines, streamribbons, and streamtubes on unstructured grids. A specialized Runge-Kutta method is developed to speed up the tracing of streamlines. Explicit solutions are derived for calculating the angular rotation rates of streamribbons and the radii of streamtubes. In order to simplify mathematical formulations and reduce computational costs, all calculations are carried out in the canonical coordinate system instead of the physical coordinate system. The resulting speed-up in overall performance helps explore large flow fields.
1993
Interactive Volume Visualization
Ma, K.-L.
Interactive Volume Visualization, Ph.D./U of U, July 1993. Advisor: Sikorski
Distributed Combustion Simulations
Sikorski, K.; Ma, K.-L.; Smith, P.J. and Adams, B.R.
Energy & Fuels, 7 (6):902-905, 1993. Funded by ACERC.
This paper reports research in progress. Two types of domain decomposition have been used in distributed computing with networked workstations for the numerical modeling of full-scale utility boilers. The numerical model is a three-dimensional combustion code that couples turbulent computational fluid dynamics with the chemical reaction process and the radiative heat transfer. Two approaches, here called microscale parallelism and macroscale parallelism, are proposed to study the intrinsic parallelism of typical combustion simulations. We describe the implementation of the microscale parallelism as well as its performance on networked workstations.
A Distributed 3D Navier-Stokes Solver in Express
Sikorski, K. and Ma, K.-L.
Energy & Fuels, 7 (6):1993, 897-902, funded by ACERC.
The Navier-Stokes equations are central to applied scientific research. The complete set of three-dimensional Navier-Stokes equations is very complex and thus requires a substantial amount of computer time as well as memory in order to obtain an accurate solution. The scalability in both processing power and memory space of distributed-memory parallel computers give promise of solving large-scale three-dimensional scientific problems based on these equations. In this paper, we describe the implementation and performance of a distributed three-dimensional Navier-Stokes solver in Parasoft's Express. We have run the solver on both the IBM Victor Computer (a 256-node transputer based system) and a token ring networked IBM RS/6000-520 workstation. Our test results demonstrate that distributed multiprocessing allows researchers to solve large-scale computational fluid dynamics problems and can improve their productivity with reducing turn around time.
Cloud Tracing in Convection-Diffustion Systems
Ma, K.-L. and Smith, P.J.
Proceedings of the Visualization 93 IEE/ACM SIGGRPHY Conference:253-259, San Jose, CA, October 1993. Funded by IBM and ACERC.
This paper describes a highly interactive method for computer visualization of simultaneous three-dimensional vector and scalar flow fields in convection-diffusion systems. This method allows a computational fluid dynamics user to visualize the basic physical process of dispersion and mixing rather than just the vector and scalar values computed by the simulation. It is based on transforming the vector field from a traditionally Eulerian reference frame into a Lagrangian reference frame. Fluid elements are traced through the vector field for the mean path as well as the statistical dispersion of the fluid elements about the mean position by using added scalar information about the root mean square value of the vector field and its Lagrangian time scale. In this way, clouds of fluid elements are traced not just mean paths. We have used this method to visualize the simulation of an industrial incinerator to help identify mechanisms for poor mixing.
1992
Parallel Volume Visualization on Workstations
Ma, K.-L. and Painter, J.S.
The International Journal of Computers and Graphics, 1992 (in press). Funded by International Business Machines and ACERC.
This paper discusses the use of general-purpose graphics workstations for interactive high-resolution volume visualization. We survey previous research results in parallel volume rendering as well as commercial products that take advantage of parallel processing to make volume rendering a practical visualization method. Our focus is on developing distributed computation methods that can distribute the memory and computational demands of volume visualization across a network of general-purpose workstations. We describe three distributed computation strategies based on ray-casting volume rendering which can be implemented on either shared-memory multiprocessor workstations or on a network of ordinary workstations. Multiple views of real-time feature extraction give tremendous insight to the volume data. Multiple variable visualization helps scientists to capture the interaction between important variables in a simulation. Divide-and-conquer rendering allows interactive high-resolution volume visualization of large data sets on a network of midrange workstations, even when the data set is too large for available memory on any single workstation. Several examples in medical imaging and computational fluid dynamics are shown illustrating the practicality of these methods.
Virtual Smoke: An Interactive 3D Flow Visualization Technique
Ma, K.-L. and Smith, P.J.
Visualization Conference, Boston, MA, October 1992. Funded by International Business Machines and ACERC.
The paper introduces a new technique for computer visualization of simultaneous three-dimensional vector and scalar fields such as velocity and temperature in reaction fluid flow fields. The technique, which we call Virtual Smoke, simulates the use of colored smoke for experimental gaseous fluid flow visualization. However, it is noninvasive and can animate, in particular, the dynamic behaviors of steady state or instantaneous flow fields obtained from numerical simulations. Virtual Smoke is based on Volume Seeds and Volume Seedlings, which are direct volume visualization methods previously developed for highly interactive scalar volume data exploration. We use data from combustion simulations to demonstrate the effectiveness of Virtual Smoke.
Volume Seedlings
Cohen, M.F.; Painter, J.S.; Mehta, A.K. and Ma, K.-L.
ACM Symposium on Interactive 3-D Graphics, Cambridge, MA, March 1992. Funded by International Business Machines and ACERC.
Recent advances in software and hardware technology have made direct ray-traced volume rendering of 3-d scalar data a feasible and effective method for imaging of the data's contents. The time costs of these rendering techniques still no not permit full interaction with the data, and all of the parameters affecting the resulting images. This paper presents a set of real-time interaction techniques that have been developed to permit exploration of a volume data set. Within the limitation of a static viewpoint, the user is able to interactively alter the position and shape of an area of interest, and modify local viewing parameters. A run length encoded cache of volume rendering samples provides the means to rerender the volume at interactive rates. The use locates and plants "seeds" in areas of interest through the use of data slicing and isosurface techniques. Image processing techniques applied to volumes (i.e. volume processing), can then automatically form regions of interest that in turn modify the rendering parameters. This "region growing" of "seedlings" incrementally alters the image in real-time providing further visual cues concerning the contents of the data. These tools allow interactive exploration of internal structures in the data that may be obscured by other imaging algorithms. Magnetic Resonance Angiography (MRA) provides a driving application for this technology. Results from preliminary studies of MRA data are included.
1991
Volume Seeds: A Volume Exploration Technique
Ma, K.-L.; Cohen, M.F. and Painter, J.S.
Journal of Visualization and Computer Animation, 1991 (in press). Funded by ACERC.
Ray-traced volume rendering has been shown to be an effective method for visualizing 3-D scalar data. However, with currently available workstation technology, interactive volume exploration using conventional volume rendering is still too slow to be attractive. This paper describes an enhanced volume rendering method that allows interactive changes of rendering parameters such as color and opacity maps. An innovative technique is provided which allows the user to plant a "seed" in the volume to rapidly modify local shading parameters. For a fixed viewing position, the user can interactively explore specific regions of interest. Furthermore, a virtual cutting technique with the exploratory seed allows the user to remove surfaces and see the internal structure of the volume. Examples demonstrate these techniques as an attractive option in many applications.
A Distributed Solution and Visualization for 3-D Flow Simulation
Ma, K.-L. and Sikorski, K.
5th SIAM Conference on Parallel Processing for Scientific Computing, Houston, TX, March 1991. Funded by National Science Foundation and ACERC.
This paper describes a distributed algorithm for solving the 3-D unsteady compressible Navier-Stokes equations, and its implementation on the Inmos T800 transputer array, in particular, the IBM Victor Computer. Numerical experiments indicate that the algorithm offers the ultimate promise of supercomputer performance on relatively low-cost and highly scalable distributed memory parallel computers. In addition, we show the use of a visualization system that we have developed for observing flow structures and for verifying simulation results.
Direct Numerical Simulation and Visualization of a Three Dimensional Planar Mixing Layer
Clarksean, R. and Ma, K.-L.
AIAA 10th Computational Fluid Dynamics Conference, Honolulu, HI, July 1991. Funded by ACERC.
The coupling of the direct numerical simulation and visualization is useful because of the insight it provides into the development and formation of structures within the flow field. We discuss the use of a volume rendering technique for the visualization of a three-dimensional planar mixing layer. Graphical data in the form of color "snapshots" and a video will be presented to demonstrate the use of the volume rendering method as a better way to understand the physics of turbulent flow.
1990
A Distributed Algorithm for the Three-Dimensional Compressible Navier-Stokes Equations
Ma, K.-L. and Sikorski, K.
Transputer Research and Applications, 4:46, (D.L. Fielding, ed.), IOS Press, 1990. Funded by National Science Foundation and ACERC.
This paper describes a distributed algorithm for solving the three-dimensional unsteady compressible Navier-Stokes (N-S) equations, and its implementation on the IMS T800 transputer array. Numerical experiments indicate that the algorithm offers the ultimate promise of supercomputer performance on relatively low-cost distributed memory parallel computers. In addition, we have developed a scientific visualization system, which converts generic scientific data into graphical forms. This visualization system allows us to observe our simulations with ease.
Ma, KL
1996
Efficient Streamline, Streamribbon, and Streamtube Constructions on Unstructured Grids
Ueng, S.-K.; Sikorski, K. and Ma, K.-L.
IEEE Transactions on Visualization and Computer Graphics, 2(2):100-108, 1996. Partially funded by ACERC.
Streamline construction is one of the most fundamental techniques for visualizing steady flow fields. Streamribbons and streamtubes are extensions for visualizing the rotation and the expansion of the flow. This paper presents efficient algorithms for constructing streamlines, streamribbons, and streamtubes on unstructured grids. A specialized Runge-Kutta method is developed to speed up the tracing of streamlines. Explicit solutions are derived for calculating the angular rotation rates of streamribbons and the radii of streamtubes. In order to simplify mathematical formulations and reduce computational costs, all calculations are carried out in the canonical coordinate system instead of the physical coordinate system. The resulting speed-up in overall performance helps explore large flow fields.
1993
Interactive Volume Visualization
Ma, K.-L.
Interactive Volume Visualization, Ph.D./U of U, July 1993. Advisor: Sikorski
Distributed Combustion Simulations
Sikorski, K.; Ma, K.-L.; Smith, P.J. and Adams, B.R.
Energy & Fuels, 7 (6):902-905, 1993. Funded by ACERC.
This paper reports research in progress. Two types of domain decomposition have been used in distributed computing with networked workstations for the numerical modeling of full-scale utility boilers. The numerical model is a three-dimensional combustion code that couples turbulent computational fluid dynamics with the chemical reaction process and the radiative heat transfer. Two approaches, here called microscale parallelism and macroscale parallelism, are proposed to study the intrinsic parallelism of typical combustion simulations. We describe the implementation of the microscale parallelism as well as its performance on networked workstations.
A Distributed 3D Navier-Stokes Solver in Express
Sikorski, K. and Ma, K.-L.
Energy & Fuels, 7 (6):1993, 897-902, funded by ACERC.
The Navier-Stokes equations are central to applied scientific research. The complete set of three-dimensional Navier-Stokes equations is very complex and thus requires a substantial amount of computer time as well as memory in order to obtain an accurate solution. The scalability in both processing power and memory space of distributed-memory parallel computers give promise of solving large-scale three-dimensional scientific problems based on these equations. In this paper, we describe the implementation and performance of a distributed three-dimensional Navier-Stokes solver in Parasoft's Express. We have run the solver on both the IBM Victor Computer (a 256-node transputer based system) and a token ring networked IBM RS/6000-520 workstation. Our test results demonstrate that distributed multiprocessing allows researchers to solve large-scale computational fluid dynamics problems and can improve their productivity with reducing turn around time.
Cloud Tracing in Convection-Diffustion Systems
Ma, K.-L. and Smith, P.J.
Proceedings of the Visualization 93 IEE/ACM SIGGRPHY Conference:253-259, San Jose, CA, October 1993. Funded by IBM and ACERC.
This paper describes a highly interactive method for computer visualization of simultaneous three-dimensional vector and scalar flow fields in convection-diffusion systems. This method allows a computational fluid dynamics user to visualize the basic physical process of dispersion and mixing rather than just the vector and scalar values computed by the simulation. It is based on transforming the vector field from a traditionally Eulerian reference frame into a Lagrangian reference frame. Fluid elements are traced through the vector field for the mean path as well as the statistical dispersion of the fluid elements about the mean position by using added scalar information about the root mean square value of the vector field and its Lagrangian time scale. In this way, clouds of fluid elements are traced not just mean paths. We have used this method to visualize the simulation of an industrial incinerator to help identify mechanisms for poor mixing.
1992
Parallel Volume Visualization on Workstations
Ma, K.-L. and Painter, J.S.
The International Journal of Computers and Graphics, 1992 (in press). Funded by International Business Machines and ACERC.
This paper discusses the use of general-purpose graphics workstations for interactive high-resolution volume visualization. We survey previous research results in parallel volume rendering as well as commercial products that take advantage of parallel processing to make volume rendering a practical visualization method. Our focus is on developing distributed computation methods that can distribute the memory and computational demands of volume visualization across a network of general-purpose workstations. We describe three distributed computation strategies based on ray-casting volume rendering which can be implemented on either shared-memory multiprocessor workstations or on a network of ordinary workstations. Multiple views of real-time feature extraction give tremendous insight to the volume data. Multiple variable visualization helps scientists to capture the interaction between important variables in a simulation. Divide-and-conquer rendering allows interactive high-resolution volume visualization of large data sets on a network of midrange workstations, even when the data set is too large for available memory on any single workstation. Several examples in medical imaging and computational fluid dynamics are shown illustrating the practicality of these methods.
Virtual Smoke: An Interactive 3D Flow Visualization Technique
Ma, K.-L. and Smith, P.J.
Visualization Conference, Boston, MA, October 1992. Funded by International Business Machines and ACERC.
The paper introduces a new technique for computer visualization of simultaneous three-dimensional vector and scalar fields such as velocity and temperature in reaction fluid flow fields. The technique, which we call Virtual Smoke, simulates the use of colored smoke for experimental gaseous fluid flow visualization. However, it is noninvasive and can animate, in particular, the dynamic behaviors of steady state or instantaneous flow fields obtained from numerical simulations. Virtual Smoke is based on Volume Seeds and Volume Seedlings, which are direct volume visualization methods previously developed for highly interactive scalar volume data exploration. We use data from combustion simulations to demonstrate the effectiveness of Virtual Smoke.
Volume Seedlings
Cohen, M.F.; Painter, J.S.; Mehta, A.K. and Ma, K.-L.
ACM Symposium on Interactive 3-D Graphics, Cambridge, MA, March 1992. Funded by International Business Machines and ACERC.
Recent advances in software and hardware technology have made direct ray-traced volume rendering of 3-d scalar data a feasible and effective method for imaging of the data's contents. The time costs of these rendering techniques still no not permit full interaction with the data, and all of the parameters affecting the resulting images. This paper presents a set of real-time interaction techniques that have been developed to permit exploration of a volume data set. Within the limitation of a static viewpoint, the user is able to interactively alter the position and shape of an area of interest, and modify local viewing parameters. A run length encoded cache of volume rendering samples provides the means to rerender the volume at interactive rates. The use locates and plants "seeds" in areas of interest through the use of data slicing and isosurface techniques. Image processing techniques applied to volumes (i.e. volume processing), can then automatically form regions of interest that in turn modify the rendering parameters. This "region growing" of "seedlings" incrementally alters the image in real-time providing further visual cues concerning the contents of the data. These tools allow interactive exploration of internal structures in the data that may be obscured by other imaging algorithms. Magnetic Resonance Angiography (MRA) provides a driving application for this technology. Results from preliminary studies of MRA data are included.
1991
Volume Seeds: A Volume Exploration Technique
Ma, K.-L.; Cohen, M.F. and Painter, J.S.
Journal of Visualization and Computer Animation, 1991 (in press). Funded by ACERC.
Ray-traced volume rendering has been shown to be an effective method for visualizing 3-D scalar data. However, with currently available workstation technology, interactive volume exploration using conventional volume rendering is still too slow to be attractive. This paper describes an enhanced volume rendering method that allows interactive changes of rendering parameters such as color and opacity maps. An innovative technique is provided which allows the user to plant a "seed" in the volume to rapidly modify local shading parameters. For a fixed viewing position, the user can interactively explore specific regions of interest. Furthermore, a virtual cutting technique with the exploratory seed allows the user to remove surfaces and see the internal structure of the volume. Examples demonstrate these techniques as an attractive option in many applications.
A Distributed Solution and Visualization for 3-D Flow Simulation
Ma, K.-L. and Sikorski, K.
5th SIAM Conference on Parallel Processing for Scientific Computing, Houston, TX, March 1991. Funded by National Science Foundation and ACERC.
This paper describes a distributed algorithm for solving the 3-D unsteady compressible Navier-Stokes equations, and its implementation on the Inmos T800 transputer array, in particular, the IBM Victor Computer. Numerical experiments indicate that the algorithm offers the ultimate promise of supercomputer performance on relatively low-cost and highly scalable distributed memory parallel computers. In addition, we show the use of a visualization system that we have developed for observing flow structures and for verifying simulation results.
Direct Numerical Simulation and Visualization of a Three Dimensional Planar Mixing Layer
Clarksean, R. and Ma, K.-L.
AIAA 10th Computational Fluid Dynamics Conference, Honolulu, HI, July 1991. Funded by ACERC.
The coupling of the direct numerical simulation and visualization is useful because of the insight it provides into the development and formation of structures within the flow field. We discuss the use of a volume rendering technique for the visualization of a three-dimensional planar mixing layer. Graphical data in the form of color "snapshots" and a video will be presented to demonstrate the use of the volume rendering method as a better way to understand the physics of turbulent flow.
1990
A Distributed Algorithm for the Three-Dimensional Compressible Navier-Stokes Equations
Ma, K.-L. and Sikorski, K.
Transputer Research and Applications, 4:46, (D.L. Fielding, ed.), IOS Press, 1990. Funded by National Science Foundation and ACERC.
This paper describes a distributed algorithm for solving the three-dimensional unsteady compressible Navier-Stokes (N-S) equations, and its implementation on the IMS T800 transputer array. Numerical experiments indicate that the algorithm offers the ultimate promise of supercomputer performance on relatively low-cost distributed memory parallel computers. In addition, we have developed a scientific visualization system, which converts generic scientific data into graphical forms. This visualization system allows us to observe our simulations with ease.