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The Massive Scale Visualization and Simulation
for Unstructured Hexahedron Mesh Data on TDWOsaka University, Kyoto University and KGT Inc.
Background

Noise predictions combined with the computational fluid dynamics (CFD) method are growing popular, because advance of CFD enable the time series
analyses of vortex. This improvements of simulation technologies enable engineers and scientists to explore the effective and theoretical design of not
only industrial materials but also medical materials.
In our own body, there are growing expectations of the researching and developing the fundamental treatment methods of speech disorders, which are
directly linked to Quality Of Life (QOL). In particular, the dental fricative voice has different characteristics of its sound production with the one of thevowel. The sound source of the dental fricative is downstream obstacle in the oral airflow field, where turbulence is dominant, although the vowel’ssound source is the vibration of vocal cords by airflow thorough them. That is to say, frontal teeth are thought to be the obstacles against the turbulenceand sound source so far. In oral therapies, the modification of oral morphological features is often happened on changing spatial positioning of jaws on
the purpose of maxillofacial orthodontic therapies, prosthetic treatments of superstructures after dental implant surgeries and inserting sports
mouthguards. Those alterations of oral morphologies may affect the characteristics of the resonance, and the magnitudes and region of the soundsources.
Therefore CFD and an acoustical simulation may predict the influence to the voice quality by such alteration of human oral geometries. To realize theprediction, huge amount of computational, storage and visualization resources are needed, which should be given in distributed environments. In orderto understand the total view of oral air flow, the volumetric visualization are appropriate. As the oral air tract has very complicated morphologicalgeometries, an unstructured mesh need to be taken and huge size of computational mesh are required to capture the vortex attitude. However, thevolume rendering of unstructured mesh is not possible so far.

Human Vocal tract

Unstructured Hexahedron Mesh

CFD Boundary Conditions

Conventional Visualization

PBVR for Velocity Field 1

PBVR for Velocity Field 2

In this project, we’ve developed three components, the volume rendering software for massively huge data size complicated geometry data,
middleware to achieve the data sharing, parallel processing and network monitoring, and an interactive human interface for visualization control in thedesign lab or etc.

Particle Based Volume Rendering

In this project, we will develop a system to visualize a large scale irregular volume dataset on a tiled display wall (TDW). The accomplishment of thisproject will be expected to become a visualization foundation for our national peta-scale computing facility which will be developed in 2011.Thedevelopment of techniques for processing irregular volumes has remained a major challenge for the visualization community. Such datasets consist
mainly of scalar data defined on collections of irregularly ordered cells whose shapes are not necessarily orthogonal cubic. In irregular volume
rendering, one of the most major issues is to relax the processing requirement for the visibility sorting or to develop a technique without the sorting. Toaddress the latter, we developed a particle-based volume rendering (PBVR) technique. In general, a volume rendering technique utilizes an illumination
model in which the 3D scalar field is characterized as a varying density emitter with a single level of scattering. Our rendering technique represents
the 3D scalar fields as a set of particles. The particle density is derived from a user-specified transfer function, and describes the number of particles
in a unit volume at any given point.
Since the particles can be considered fully opaque, no visibility sorting processing is required during rendering process, and this is advantageous froma distributed processing perspective.
Currently, we confirmed that the technique can generate an image which is equivalent to the volume ray-casting's and deal with large irregular volumedatasets in which the maximum number of tetrahedral cells exceeded one billion. In 2008, we will develop the remote visualization system in which a
set of particles are transmitted through a high speed network. The next year, we will develop an integrated renderer which can process particles
generated from geometric datasets such as polygons, polylines. In the final year, we will develop a streaming system which renders time-varying
irregular volume datasets.

Interactive Human Interface

In this three-year project, the user interface team aims to develop a set of novel 3D interaction techniques for investigation and exploration of volumetricdata. As opposed to a typical polygon-based virtual environment, interactive examination of volumetric data of interest exhibits a number of technicalchallenges to tackle; e.g. huge data size hinders its rendering at an interactive frame rate at the highest pixel resolution of the tiled display,self-occlusion prevents observation of an internal structure of interest. The user interface team will propose and validate new solutions to these
problems by exploiting levels-of-detail techniques, interactive space-warping, multi-view rendering, and a diverse range of 3D interaction techniques.

Portable CMC TDW
Contact : Haruo Takemura,Director of CMC
E-mail : takemura@cmc.osaka-u.ac.jp