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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
Figure 2. SAR DEM of Santa Ana Volcano, El Salvador
3. COST ANALYSIS
Cost component of a project plays an important role when it is
considered from the point of productivity view. Since effective
resource management requires economic data acquisition,
imagery that is needed for photogrammetric mapping should be
obtained at the lowest cost possible. However, the term
“economic data acquisition” does not eventually imply getting
the cheapest but suggests supplying the most purpose fitting
material at lowest price available. In order to figure out the cost
aspect of the photogrammetric image acquisition, airborne and
spaceborne image cost analysis has been scrutinized separately.
3.1 Airborne imagery cost analysis
Airborne imagery is the set of images that are captured by the
sensors mounted to an aircraft. Airborne imaging comprises of
flight and ground operations, where flight operations involve
aircraft and sensor costs while ground operations cover post-
flight procedures such as developing and digitizing the films
taken by analog camera or downloading and processing of the
data collected by the digital camera.
Aircraft cost is comprised of annual fix cost and direct
operating cost. Annual fix cost involves, hangar expenses,
insurance payments, crew salary, and various administrative
expenses such as pilot recurrent training, maintenance and
navigation publication subscription fees, etc. Direct operating
cost mainly covers the fuel and maintenance expenses at hourly
basis. Aerial survey crew consists of pilot(s), navigator/camera
Operator and aircraft mechanic. Some crew formations could
comprise of only two persons such as pilot/mechanic and
navigator/camera operator.
Camera cost covers maintenance and personnel expenses for
both analog and digital aerial cameras where an extra film
expense should be added in case of analog camera use. Post-
flight ground operation costs involve maintenance and
personnel expenses, however an additional chemical cost shall
be taken into account for developing the exposed films.
Aerial survey aircraft can be sorted in three main categories as
low, medium and high altitude airplanes that have 10000, 20000
and 30000 feet ceiling respectively. In order to figure out the fix
annual cost share within the hourly cost of the aircraft,
estimated annual flight time of the aircraft should be presumed
in advance and, in this study, it is assumed to be 400 hours.
649
Digital camera operational cost is rather easy to determine
while analog camera cost prediction becomes more complicated
because of the film. As it is known, analog aerial cameras use
mainly three types of aerial films (actually four when B&W
infrared film is included) as Black & White, Color and Color
Infrared (False Color) Amount of the film required for a
photographic mission depends to the photo scale and the size of
the area to be surveyed. Due to the divergence at aerial film
prices, the film costs are given separately. In order to determine
the operational aerial survey costs that are given in Table 3, it is
assumed that a region having 40000 km? area and 1500 m
reference terrain elevation is to be flown with a 23*23 cm frame
camera having 150 mm focal length and flight conducted with
60% forward and 30% lateral overlap, and at the maximum
ceiling altitude of the aircraft, which corresponds to 1:12500,
1:25000 and 1:50000 photo scales respectively.
Altitude | (feet) 10000 20000 30000
Photo scale | l/... 12500 25000 50000
Aircraft | (USS/hr) 522 643 881
Analog Camera | (US$/hr) 315 315 315
B& W 32237 8105 2072
Film (US$) | Color 93917 23613 6038
Color IR 171500 43120 11025
Digital Camera | (USS/hr) 158 158 158
Table 3. Aerial survey costs.
It is obviously noticed from the Table 3 that camera cost is fix
for all scales while aircraft cost increases and aerial film cost
decreases relative to scale factor. The increase in the aircraft
cost is because of the relatively high direct operation costs of
the high performance aircrafts, which are capable of getting
imagery at small scales. On the other hand, the decrease in film
cost arises from the low amount of film and the less laboratory
process requirement as a result of small-scale photo survey.
In order to determine the imagery cost at a common basis,
which allows comparison with the satellite imagery cost, aerial
imagery costs computed in area basis are presented at Figure 4.
14
2
10
8
= 8
N
-
Do
0
1:25000 1:50000
1:12500
9,18
10,72
12,66
6,80
EB&W 9.78 12,01
Bl Color
Li Color IR
O Digital
[0.17
10,66
8,00
Figure 4. Airborne imagery costs per sq km
