The brain database will be embedded in three dimensions. The user
starts a typical investigation by navigating through the MR images in
a coarse 3D model of the brain to a site of interest. The user then
zooms to higher resolution confocal images embedded in the MRI
landscape. This real-time navigating and zooming we call ``flying.''
The scientific value of the data and the distributed nature of the
database impose a series of user-level requirements that the flying
interface should satisfy:
Wide Spread Use. We estimate the number of users who may be
interested in using the database to be 10,000 (half the number of
members of the Society for Neuroscience in 1994), the average day to
be 10 work hours, the average work week to be 5 days and the average
work month to be 4 weeks. We can predict the average number of
simultaneous database users based on some possible usage amounts:
Twenty-four Bit Color. As often as possible, the database will
express experimental data in its purest form, so expensive raw data
can be analyzed and reanalyzed by researchers worldwide. Images
include up to three layers of eight bit gray-scale, with each layer
representing one brain chemical. The final images include 24 bits of
color, all important to the scientists who view it.
Three Dimensions. Since the anchoring MR images are three
dimensional, flying must be allowed in all three dimensions. This
necessitates computing two dimensional frames from the three
dimensional images. The computation can take place by two
different methods:
Remote Flying:
In remote image processing the server does
the image computation and transfers only a 2D frame to the client.
We estimate Remote Flying will require sending 24 Mbits (a
mega-pixel) of data per frame.
Local Flying:
In local image processing the server transfers
the 3D data and the client does the image computation. We estimate
Local Flying will require sending 384 Mbits (the 3D region of the
brain) of data per frame.
Smooth Navigation. Flying must be very smooth even over a
varied, non-dedicated network. This necessitates a motion picture
quality rate of 30 frames per second, and jitter control to compensate
for network variance.
Adaptability. Flying must adapt to a wide variety of resources,
including varying CPU and disk types and non-dedicated variable
bandwidth networks.
