Biomedical Engineering Reference
In-Depth Information
the hardware-accelerated, per-pixel blending operation
can be used for rendering.
putting them back together to produce a 3D image that
did not add any new information. Thus, volume render-
ing was considered to be clinically useful only in cases
where the 3D morphology could provide a visualization
advantage.
But soon, new forms of imaging techniques were de-
veloped that contained functional information associated
with the anatomical information in the images. Such
functional imaging techniques needed volume rendering
to visualize the functional information that could not be
visualized otherwise. Volume rendering benefited various
functional visualization applications that required in-
vestigative imaging. To illustrate investigative visualiza-
tion several examples are now presented. The difference
between investigative visualization and illustrative visu-
alization is not in their fundamental concepts, but in their
specific applications.
6.6.3 Investigative visualization
As the concepts in illustrative visualization became mature
enough, they became widely used in various applications.
The concept of investigative visualization slowly emerged
as a form of visualization for addressing specific questions
that required collective use of various graphics concepts
described in the earlier section on illustrative visualization.
This corresponds to
fourth generation systems.
The application of many 3D volume visualization
techniques remained limited to specific purposes where
the needs could not be fulfilled otherwise. The use of 3D
visualization techniques was not widespread because of
several potential factors: It usually required a certain
amount of specialized prior knowledge about the tech-
nique, the computation time and the cost of required
high-performance systems were both high. Imaging ad-
vances in medicine helped systems produce better 3D
images by slicing the sampling space into sets of image
planes, while the rendering techniques were tools for
Stereoscopic 3D visualization
One of the most important developments in volume vi-
sualization that demonstrated the full potential of
volume rendering is stereoscopic 3D rendering. A stereo
pair (left and right-eye views) of plain volume-rendered
Figure 6.6-10 Visualization using back-projection reconstruction. (Left) Illustration of reconstruction. (Right) Clinical applications.
(Top) Coronary vessel studies. (Bottom) Aneurysm localization studies using conventional sweep arm rotational angio systems.
(Images courtesy of M. Solaiyappan, Nick Bryan, Timothy Eckel, Cliff Belden.)
