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n, which was a
poster session
was also held, at which seven posters were presented on
diverse areas of application. Proceedings for the
workshop will be published later this year (Ehlers, et al.,
1994).
Another workshop on 'Visualization and GIS' is
tentatively scheduled for May of 1995 in Germany.
20 SYSTEMS TECHNOLOGY ADVANCES
A critical review of the systems aspect for the processing
of geographic data reveals that progress in this area has
been primarily driven by advances in technology. These
advances come from fields remote sensing,
photogrammetry, surveying, or mapping.
In particular, progress in computer science and the major
acceptance of geographic information systems (GIS) as a
unifying technology are challenging the "separation of
disciplines". Consequently, the shift toward integrated
systems for processing of geoinformation is driven by
advances outside the disciplines traditionally represented
by ISPRS. It is, however, imperative that ISPRS
responds to these technological challenges.
We need an integrated approach for research,
development, and education in geoinformation processing
which might be coined "geoinformatics". If we do not
aggressively adopt such an integration, photogrammetry
and remote sensing might end up as minor subareas
within computer science and informatics.
In the following sections we will try to summarize
advances in hardware and software which generally apply
to all systems involved in geoinformation processing.
2.1 Hardware Advances
11.1 Computational Power. The advances in
speed and power of computers have been phenomenal.
Processor speed has approximately doubled every year
since 1986. General purpose RISC processors are
available with speeds in the range between 25 and 100
MIPS (million instructions per second). Graphics and
image processing computers running at 300 MIPS (e.g.
Vitec or Silicon Graphics) are available. These computers
are programmable and can be used for a wide variety of
tasks (Faust, et al., 1991a).
Concurrent with advances in the workstation or
minicomputer processing power, advances are being
realized in the PC class. The Intel 80486 and Pentium
and the Motorola 68040 and PowerPC chip are providing
the power to do tasks which have been traditionally
reserved for mini or mainframe computers.
Almost all general purpose computers have been, until
recently, single CPU computers. The availability of
multi-processor machines is becoming more common.
There are already several machines on the market such as
the NCUBE/10, Sun Sparc10 and others.
These increases in power in off-the-shelf hardware mean
that is no longer necessary to design and build single
purpose image processing or geographic information
systems. The days of the dedicated image processing
station are rapidly disappearing.
2.1.2 Scanning Technology. Scanning is a widely
accepted technique for the input data into a
geoinformation processing system. It is often used to
input map data from hardcopy to a GIS. Due to the
unfortunate lack of operational digital aerial cameras, it is
also the most common approach to acquiring data for a
digital photogrammetric system. In order to achieve the
resolution of an analog photo in a digital image, it must
be scanned at approx. 10mm (2500 dpi) (Ehlers, 1991).
While there are a number of scanners available which are
capable of such resolutions (i.e. Zeiss Photoscan, HAI
100, Vexel), they are quite expensive.
For many applications, however, it is not necessary to
have a digital product with the full resolution of an aerial
photo. The field of desktop publishing has, to a large
degree, driven most of the recent advances in desktop
scanning. Users in this field have demanded, and received,
higher resolution, color capability and lower cost.
Manufacturers are now offering scanners that offer
resolutions of 600 or 1200 dpi in format sizes suitable
for scanning aerial photos which are as much as an order
of magnitude cheaper than those offered specifically for
photogrammetric use. For applications not requiring full
photographic resolution, the results obtainable from
desktop scanners offer suitable resolution and accuracy
(Sarjakowski and Lammi, 1991).
2.1.3 Storage Capacity. The analysis of geographic
data requires the storage of large amounts of data.
Advances in disk drive and other mass storage technology
have kept up with those in the processor field.
We have progressed from a point where 50 MB of hard
disk storage required a cubic meter or more to being able
to store 1.2 GB on a 3-1/2" hard drive that occupies
about 0.2 cubic meters (in external configurations). The
form factor for hard drives continues to decrease along
with the increase in capacity. 3-1/2", 500 MB drives are
common and smaller drives are being developed and
introduced.
Other forms of magnetic media have also advanced. The
3-1/2", 1.2 or 1.4 MB floppy is the defacto standard.
Magnetic tape systems such as the Exabyte are capable of
storing 5 GB of data on a cartridge (with compression)
that is roughly the size of an audio cassette.
Optical or magneto-optical (M-O) storage is further
increasing storage capacity. CD-ROM and WORM
(Write Once, Read Many) drives are commonly used for
archiving data. M-O systems with read/write capabilities
currently store 650 MB per disk and, with foreseen
technical advances, this is expected to increase to 10 GB
within the next 5 years. When coupled with juke box
mechanism, users will have access to 100's of gigabytes
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