Date: Thu, 15 Dec 1994 14:45:29 GMT
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Imaging sharpens medical diagnoses: doctors get a clearer look
into the human body.
Killmon, Peg
Image processing is used in a wide range of medical applications
including diagnosis, planning surgery, providing a surgeon with
visual references, designing prostheses, and simulating
corrective procedures. PCs connected to superminicomputers,
combine with specialized imaging subsystems, collect, store,
digitize, process, and display data from such devices as CT, NMI,
ultrasound, and MRI scanners. Imaging systems range from $2,000
boards to $10,000 to $100,000 complete systems. Advantages in
diagnosis include reducing blurred images and easier comparison,
highlighting, isolation, and magnification of images. 3D systems
provide additional help in pinpointing tumors, measuring lung
volume, and constructing prostheses. Real-time capability
provides additional visualization and planning capabilities.
Several medical imaging systems and their applications are
briefly described.
Computer Graphics World
(Oct 1987) v10 n10 p49(4)
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Koyamada, Koji
Nishio, Toshihiko
This paper describes a method for visualizing the output data set
of a 3D finite element method result. A linear tetrahedral
element is used as a primitive for the visualization processing,
and a 3D finite element model is subdivided into a set of these
primitives, which are generated at every solid element. With
these primitives, isosurfaces are visualized semitransparently
from scalar data at each node point. Two methods are developed
for the visualization of isosurfaces with and without
intermediate geometries. The methods are applied to output data
sets from some simulation results of a semiconductor chip. These
are visualized, and the effectiveness of the method is discussed.
(Reprinted by permission of the publisher.)
Volume visualization of 3D finite element method results.
(technical)
IBM Journal of Research and Development
(Jan-March 1991) v35 n1-2 p12(14)
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A hybrid ray tracer for rendering polygon and volume data.
(Volume Rendering) (technical)
Levoy, Marc
Many medical data visualization applications require that
geometrically defined objects and sampled fields appear together
in a single image. The problem of rendering mixtures of
polygonally defined objects and sampled scalar functions of three
spatial dimensions is examined. Usually the polygon and volume
data in such systems are converted into a common representation,
which requires a binary classification of the volume data and
leads to misclassification of some small features. A hybrid
rendering algorithm is presented that can be used to display both
types of data directly, preserving the original representations
and eliminating conversion artifacts in generated images. The new
technique presented is based on volume rendering, which is used
to display sampled fields by approximating the transmission of
light through a colored semitransparent volume.
IEEE Computer Graphics and Applications
(March 1990) v10 n2 p33(8)
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Efficient ray tracing of volume data. (technical)
Levoy, Marc
New methods for visualizing discrete multidimensional data are
being developed in response to the increasing availability of
graphics workstations in the scientific and computing fields.
Volume rendering technique visualizes sample scalar or vector
fields of three spatial dimensions; the array is displayed
directly, it does not have geometric primitives fitted to it
first. A subset of this technique is to assign a color and an
opacity to each voxel and compute a two-dimension projection of
the resulting colored semitransparent volume. The advantages of
these techniques are superior image quality and ability to
generate images without explicitly defining surface geometry; the
main disadvantage is cost. A front-to-back image-order
volume-rendering algorithm uses both hierarchical spatial
enumeration and adaptive termination of ray tracing to reduce
costs. This algorithm can be used for any opacity assignment
operator that divides a volume data set into coherent regions of
opaque and transparent voxels.
ACM Transactions on Graphics
(July 1990) v9 n3 p245(17)
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The visible volume. (overview of a special report on volume
visualization technology) (Special Report)
LoPiccolo, Phil
Volume visualization is a scientific, computer-aided
visualization method which enables scientists and engineers to
look inside almost any object with non-destructive and
non-invasive techniques. The term also applies to a technique
called volume rendering which can be perceived as
three-dimensional image processing. Other volume visualization
techniques include geometry-based surface rendering methods and
quantitative measuring methods. Computed tomography, ultrasound
and magnetic resonance are three methodologies which generate the
data used in volume visualization. In addition, recent
advancements in imaging speed and resolution in hardware
technology have helped the development of volume visualization.
Computer Graphics World
(April 1991) v14 n4 p44(2)
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Internal medicine. (advances in rendering technology enhance
medical imaging technology) (Special Report: part one)
Mahoney, Diana Phillips
A new type of volume visualization called volumetric or
voxel-based rendering which helping medical professionals make
accurate diagnoses. Volumetric rendering provides computerized
representations of volume images in three dimensions. Research
and medical centers use computers to gather information from
two-dimensional sources and to assimilate the data into
three-dimensional volumetric images, enabling practitioners to
focus on comprehending information instead of gathering
information. Geometric methods have also been used to develop
three-dimensional images, but volumetric rending creates images
of higher quality because it does not use techniques which cause
fine-line distortions. Numerous examples are presented of medical
and research centers that are applying the volumetric rendering
technology.
Computer Graphics World
(April 1991) v14 n4 p47(5)
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Small worlds. (examining life under the microscope with volume
visualization) (Special Report: part two)
Mahoney, Diana Phillips
Biomedical research has achieved many benefits by utilizing
advances in computer visualization and optical microscopy.
Currently, many research centers are using volumetric rendering
to enable scientists to view three-dimensional microstructures in
three dimensions, providing scientists with the ability to gather
more complete data. The confocal microscope is an example of the
application of volumetric rendering technology. The microscope
obtains a microscopic structure, which is then digitized by a
video camera and a frame grabber. The technology enables
researchers to visualize live cells. Another application combines
volumetric rendering with X-ray crystallography to develop a drug
design built around the structures of receptors and enzymes.
Researchers believe the biomedical microscopy application of
volumetric visualization technology is boundless because it can
be used in many areas including AIDS and Cancer research.
Computer Graphics World
(April 1991) v14 n4 p57(3)
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Volumetric rendering of computed tomography data: principles and
techniques. (technical)
Ney, Derek R.
Fishman, Elliot K.
Magid, Donna
Drebin, Robert A.
Three-dimensional imaging is intended to improve the interface
between the radiologist making a medical diagnosis and the
clinician carrying out the treatment. Data from a transaxial
computed tomography (CT) scan are usually displayed in a
two-dimensional planar format, which does not communicate the
three-dimensional nature of the area represented. Pixar, the
computer graphics division of Lucas Films, has developed an
algorithm for volumetric rendering, which is a technique that
allows three-dimensional images to be rendered of any volume data
set. The technique improves on other image generation methods by
supporting the use of a mixture paradigm for representation of
the volume to be rendered and using mathematical techniques to
reduce or eliminate aliasing. Specific aspects of volumetric
rendering are examined as they apply to medical CT data.
IEEE Computer Graphics and Applications
(March 1990) v10 n2 p24(9)
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Visualizing and modeling scattered multivariate data.
Nielson, Gregory M.
Foley, Thomas A.
Hamann, Bernd
Lane, David
Mathematical models are developed for the computer visualization
of sampled scattered volumetric data in a three-dimensional
volume and scattered surface-on-surface data on a 3D surface.
Scientific data does not always appear in a tractable uniform
grid, so mathematical models are required to interpolate or
approximate an entire domain from available scattered data.
Modeling volumetric data employs the multiquadratic method for
solving of one dependent and three independent variables, while
visualizing the data assumes the data is given over a cuberille
grid and uses isovalue surface and volume rendering methods
interactively. Surface-on-surface data modeling is similar to
volumetric modeling but with one data site on a surface in 3D
space. Visualizing surface-on-surface data is accomplished by
drawing isovalue curves on a surface or through the use of a new
hypersurface projection graph.
IEEE Computer Graphics and Applications
(May 1991) v11 n3 p47(9)
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A functional view of proteins.
Olson, Arthur J.
Goodsell, David S.
Computer graphics is one way to produce comprehensible views of
structural information, which help researchers relate the
thousands of atomic positions in a complex molecule to the
biological functions that the molecule performs. Bond diagrams
and shaded spheres are two of the traditional methods used in
molecular visualization. Computation and computer graphics are
now being used to generate new representations, which help
scientists see global patterns and use structure to hypothesize
function. A new method of visualizing aggregate molecular
properties is to use volume rendering techniques in conjunction
with geometric rendering.
IEEE Computer Graphics and Applications
(Jan 1991) v11 n1 p15(3)
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Modeling and image processing for visualization of volcanic
mapping. (technical)
Pareschi, Maria Teresa
Bernstein, Ralph
In countries such as Italy, Japan, and Mexico, where active
volcanoes are located in highly populated areas, the problem of
risk reduction is very important. Actual knowledge about volcanic
behavior does not allow deterministic event prediction or the
forecasting of eruptions. However, areas exposed to eruptions can
be analyzed if eruption characteristics can be inferred or
assumed. Models to simulate volcanic eruptions and identify
hazardous areas have been developed by collaboration between the
IBM Italy Pisa Scientific Center and the Earth Science Department
of Pisa University (supported by the Italian National Group of
Volcanology of the Italian National Research Council). The input
to the models is the set of assumed eruption characteristics: the
typology of the phenomenon (ash fall, pyroclastic flow, etc.),
vent position, total eruptible mass, wind profile, etc. The
output of the models shows volcanic product distribution at
ground level. These models are reviewed and their use in hazard
estimation (compared with the more traditional techniques
currently in use) is outlined. Effective use of these models, by
public administrators and planners in preparing plans for the
evacuation of hazardous zones, requires the clear and effective
display of model results. Techniques to display and visualize
such data have been developed by the authors. In particular, a
computer program has been implemented on the IBM 7350 Image
Processing System to display model outputs, representing both
volume (in two dimensions) and distribution of ejected material,
and to superimpose the displays upon satellite images that show
3D oblique views of terrain. This form of presentation, realized
for various sets of initial conditions and eruption times,
represents a very effective visual tool for volcanic hazard
zoning and evacuation planning. (Reprinted by permission of the
publisher.)
IBM Journal of Research and Development
(July 1989) v33 n4 p406(11)
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Pommert, Andreas
Bomans, Michael
Hohne, Karl Heinz
Magnetic resonance angiography builds on magnetic resonance
imaging by providing stacks of parallel cross-sectional images
that show the blood vessels distinctly. MRA images can be
obtained from MRI scanners, although blood vessels do not display
well in two dimensional scans. Volume visualization techniques
were developed to achieve a more natural presentation of
tomographic volume data. Aliasing effects can result in strong
artifacts when applied to MRA data. Detailed is an overview of
MRA technology. Areas discussed include new angiographic
techniques and various applications of the technology.
Volume visualization in magnetic resonance angiography.
IEEE Computer Graphics and Applications
(Sept 1992) v12 n5 p12(2)
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Insightful analysis. (using volume visualization in industrial
and engineering application areas) (includes related article on
volume visualization in flight simulation) (Special Report: part
four)
Porter, Stephen
Many industrial engineers are discovering the benefits of using
volume visualization, especially in the area of non-destructive
evaluation (NDE). NDE uses X-rays to discover defects, cracks and
holes in materials and parts. Information gained from NDE is then
used in failure analysis, process control and quality control.
Volume rendering, an aspect of volume visualization, enhances NDE
capabilities because it provides the ability to conduct
inspections in three-dimensions. The US Air Force is conducting
experiments with three-dimensional image processing because it is
attempting to develop a system to inspect rocket engines for
intercontinental ballistic missiles. Volume rendering can
eliminate ambiguity and provide a way to examine information that
is more natural. However, a drawback to the technology is that
the software is hard to use. Also, many tasks still can be
accomplished using two-dimensional technology.
Computer Graphics World
(April 1991) v14 n4 p75(4)
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Data visualization in archaeology. (technical)
Reilly, Paul
Archaeological field work produces vast amounts of
three-dimensionally recorded data which can only be analysed
using computers. Developments in data-visualization techniques
are continually increasing the volume and complexity of data that
can be studied meaningfully. In particular, three systems
developed at the IBM United Kingdom Scientific Centre have been
applied in a wide variety of archaeological situations: a
graphics-database system called the Winchester Graphics System
(WGS), IBM's IAX (Image Applications eXecutive) image processing
system, and the WINchester SOlid Modelling system called WINSOM.
It has been shown that these systems not only permit well-known
problems to be answered in new and interesting ways but have
freed archaeologists to explore previously undiscovered avenues
of research. The techniques developed using these systems also
have major implications for education and training. (Reprinted by
permission of the publisher.)
IBM Systems Journal
(Dec 1989) v28 n4 p569(11)
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A declarative approach to visualizing concurrent computations.
(Visualization in Computing) (technical)
Roman, Gruia-Catalin
Cox, Kenneth C.
Visualization is examined as a way to understand programs made up
of large numbers of concurrent processes in an attempt to
establish a new technical foundation for research into the
monitoring and debugging of large-scale concurrent programs. Such
programs produce a very high volume of information that exceeds
the ability of people to assimilate it in textual form. The human
visual system is better able to process information in the form
of images rather than in the sequential form of textual
techniques. The level of abstraction in the displayed information
must be increased as the number of processes grows. Visualization
systems that provide flexible abstractions help programmers
select displays that are easily specified and understood.
Arguments are presented in favor of the declarative visualization
paradigm and a case is built for program verification as the
technical foundation for a formal approach to visualization.
Computer
(Oct 1989) v22 n10 p25(12)
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Rosenblum, Lawrence J.
Brown, Bruce E.
The term 'visualization' is used to indicate graphic
representation of data to make its implications clearer.
Scientists hope their work will progress from 'visualization' to
'realization' or complete understanding. The theme of this issue
of IEEE Computer Graphics is visualization and topics covered
include scientific data visualization, the use of visualization
to produce tools for developing entertainment, improved volume
measuring algorithms, experiments in higher dimensional space and
new interfaces. Visualization also encompasses virtual reality
experiments and scientists expect to discover whether or not it
is useful for a more complete understanding of data. A special
section of the journal covers CD-ROM-based applications that
include sound, text and graphics.
Guest editors' introduction: visualization. (Cover Story)
IEEE Computer Graphics and Applications
(July 1992) v12 n4 p18(2)
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Acoustic holography. (Naval Research Laboratory use of
holography)
Schuette, Lawrence C.
Acoustic holography is an important diagnostic technique for
analyzing radiating structures. The Naval Research Laboratory
(NRL) collection and analysis of acoustic holographic data
centers around the Generalized Near Field Acoustical Holography
(Genah) technique, which was developed for the analysis of
submerged, radiating, cylindrical objects. A volume visualization
and animation technique using a Silicon Graphics 4D Iris Graphics
Workstation was developed from the analysis of acoustic holograms
generated with Genah. Animation and volume visualization
techniques applied to acoustic holographic data increased
understanding of the mechanisms of a radiating structure.
IEEE Computer Graphics and Applications
(July 1991) v11 n4 p12(2)
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Visualizing asthma: the creation of a complex medical infographic
in Aldus Freehand. (tutorial)
Silverstone, Stuart
It is possible to create a complex medical illustration using
Aldus Corp's Aldus FreeHand. Such a drawing of the anatomy of an
asthma attack appeared in US News and World Reports. The graphic
designer that created the 'infographic' used a six-step process,
including reusing an image from another layout, scanning a hand
sketch from a photo, constructing layers, drawing for appropriate
realism, rendering for shadows and volume and designing a layout.
Detailed instructions are described.
Aldus Magazine
(July-August 1991) v2 n5 p40(3)
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Investigation of medical 3D-rendering algorithms: surface
rendering. (technical)
Tiede, Ulf
Hoehne, Karl Heinz
Bomans, Michael
Pommert, Andreas
Riemer, Martin
Wiebecke, Gunnar
The quality of different surface rendering algorithms is compared
using quantitative and qualitative measures of image quality. A
ray-casting algorithm is used to scan the gray-scale volume from
the desired direction of view using the Voxel-Man program; the
projection image is formed by derivation of a gray value from the
intensity profile encountered by each ray. Two types of
projections are studied: a surface voxel identified by an
intensity threshold or by its attribute gained in a previous
segmentation step (binary segmentation), and opacity assigned to
each voxel followed by production of a semitransparent
presentation based on the opacities (fuzzy segmentation).
Z-buffer gradient, gray-level gradient, adaptive gray-level
gradient and marching cubes with two extensions are tested for
the group of surface-shading algorithms. It is found that use of
a combination of shading methods yields the best visualization.
IEEE Computer Graphics and Applications
(March 1990) v10 n2 p41(13)
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A new 'inlook' on life. (computer graphics applied to biological
sciences)
Van Zandt, William
Argiro, Vincent
Volume rendering is an advanced three-dimensional computer
graphics visualization technique that enables improved
interaction between objective image acquisition and measurement
tools and scientific understanding and intuition, exemplified by
the use of the techniques in experimental biology. Volume
rendering represents 3-D objects as constructs of 'voxels,'
discrete volumetric building blocks. The methodology is easy to
understand, and results of the process are easy to interpret. The
Laboratory for Advanced Biological Cell Imaging at Fairfield,
IA's Maharishi International University uses volume visualization
technology for the observation and analysis of nerve cell
microscopy. A viable, real-time, interactive biological
volume-rendering system is found to require a large memory,
sufficiently high data-traversal speed, and fast 3-D coordinate
transformations and calculations.
UNIX Review
(March 1989) v7 n3 p52(5)
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Wilhelms, Jane
Gelder, Allen Van
Visualization algorithms are often prevented from providing
interactive rendering because of the large size of many volume
data sets. Using hierarchical data structures can help prevent
exploration of useless regions. Detailed is the use of the octree
hierarchical data structure, which is well suited to the
six-sided cell structure of many volumes. A new design is
detailed for octree representatives of volumes whose resolutions
are not a power of two. Also discussed is a caching method that
passes information between octrees with different visitation
times. Also presented are space and time comparisons for
octree-based methods versus more traditional methods.
Octrees for faster isosurface generation. (Technical)
ACM Transactions on Graphics
(July 1992) v11 n3 p201(27)
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Yoo, Terry s.
Neumann, Ulrich
Fuchs, Henry
Pizer, Stephen M.
Cullip, Tim
Rhoades, John
Whitaker, Ross
Volume rendering is used to produce complex images of higher
dimensional data, but too often the images are presented in a way
that makes analysis difficult. Researchers are developing
user-driven image interfaces to remedy the situation. These
interfaces are interactive and allow user control of the semantic
classification tool. Users are able to select a region within the
image for closer scrutiny. A comparison of multipass shear,
splatting and trilinear reconstruction techniques results in the
development of a parallel algorithm to produce both the necessary
fast updates and high image quality. The human brain is able to
interpolate missing data in images when motion is present and the
volume rendering system is able to use this to improve image
quality.
Direct visualization of volume data. (computer graphics)
(Technical)
IEEE Computer Graphics and Applications
(July 1992) v12 n4 p63(9)