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1 Ele-
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allows
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x data
of various sources in one instrument. Though it is
increasingly difficult to draw the line between pho-
togrammetry, remote sensing and GIS areas.
2 Cost factors of digital photogrammetry
It is quite clear that DPW solution and new features
are able to bring much higher productivity into pho-
togrammetric production. But DPW has been consid-
ered to be very expensive technology. Cost factors in-
fluencing digital photogrammetric production can be
divided into four groups:
1. Computer hardware and system software
2. Image processing hardware and software
3. Maintenance fee
4. Cost of labour
2.1 Computer hardware and system software
Most of DPW currently run on UNIX workstations
with RISC processors and special-purpose graphics
accelerators. These workstations are quite expensive
(reasonably equipped — from 30,000 US$ upwards) and
are usually used only for these special photogrammet-
ric tasks. UNIX software is also very expensive in
common as well as the use of UNIX environment in-
creases expenses for training and wages of operators.
Therefore to reduce the expenses on computers and
software, new digital photogrammetric systems should
run on a standard personal computer with minimal
attachments. The advantages of RISC processors and
special-purpose accelerators over Intel CISC proces-
sors and PC plug-and-play architecture are rapidly
disappearing, Pentium and new P6 processors offer
adequate power for most of DPW tasks.
The use of standard personal computers creates the
possibility to utilize them for other tasks and to in-
crease the effectiveness of hardware as well as soft-
ware expenses. Standard PC software is also cheaper
in common and the use of standard Windows environ-
ment (MS Windows, Windows 95, Windows NT) is for
many people well known and quite natural. So that
the use of standard PC environment can also decrease
expenses for operator training. The same look and
feel of photogrammetric software with usual editors
and computer tools also brings higher productivity to
their utilization.
2.2 Image processing hardware and software
The biggest problem of digital photogrammetry seems
to be scanning and image data storage, because of
its size. Primary data collection is still nearly always
made by conventional photogrammetry, when digital
photogrammetric systems need a conversion of the
301
analogue image to digital format by scanning. Prices
of the equipment for this purpose can range from 2,000
US$ to 300,000 USS.
One aerial black-and-white photograph in 23 x 23 cm
format scanned on 1000 DPI represents about 100 MB
image data. In the case of true colour images it is even
three times more. It means that in the case of stereo
pair and its orthophoto it is necessary to have 1 GB of
free disk space for true colour raster data processing.
Image compression techniques and modern computer
storage devices (such as optical disks and high capac-
ity tapes) can currently solve the problem with storage
capacity for data archives but it still remains need for
fast and large disks for data processing.
Another problem seems to be the price of DPW soft-
ware. Current professional systems are mostly run-
ning in UNIX environment. So that it is very diffi-
cult to find system, which offers full range of func-
tionality with price up to 10,000 US$. To take full
advantage of digital photogrammetry, it is necessary
to support main photogrammetric tasks (such as dig-
ital orthophoto processing, automatic generation of
DEM and stereoplotting) as well as close link with
full-featured GIS system. The use of standard per-
sonal computer environment also enable users to use
all advantages of current software integration and in-
creases effectiveness of software expenses.
2.3 Maintenance fee
There are no mechanical /optical moving parts and in-
struments in digital photogrammetry, thereby elimi-
nating and reducing maintenance difficulty. But hard-
ware and software maintenance fee should be consid-
ered. From this point of view standard PC environ-
ment greatly reduces maintenance fee. Plug-and-play
PC architecture enable users smoothly upgrade power
and capacity of computer (processor, memory, disks,
other peripherals). It is also possible to move special
equipment and software for photogrammetry to new
(and more powerful) computer and use older hardware
for other tasks.
UNIX operating system and environment was consid-
ered more reliable and well-suited for large computa-
tional tasks and big data management, which is neces-
sary for image processing and digital photogrammetry.
Windows NT have currently the same reliability and
provide also sufficient features for large computations
and big data management. Software for Windows
95 and Windows NT can currently utilize standard
system functionality such as preemptive multitasking,
multithreading, advanced OpenGL graphics etc.
2.4 Labour costs
Even though a lot of operations can be done auto-
matically there is still a lot of manual work. Com-
puter programs have to be operated, control points
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996
