Home' Position : Position 90 Aug-Spt 2017 Contents Think drone surveys are going
to replace manned aircraft?
Erron Gardner uses both and
says you should think again.
With the drone industry’s
marketing machine in full
swing, you could be forgiven for
thinking that unmanned aircraft are far
more economical at capturing remotely
sensed data than manned aircraft.
The remotely piloted aircraft system
(RPAS) industry has pitched their
machines to be the perfect mapping
solution, especially over smaller to
medium sized projects. After all,
everybody knows that manned aircraft are
extremely expensive to operate, right?
Surprisingly, this is not necessarily the
case, and manned data capture even on
small to medium projects can often be
just as, or even more, cost effective as the
RPAS solution. Articles appear regularly
about new developments in RPAS
technology, but little if any is heard about
advancements in manned survey systems.
So let’s have a look at the available RPAS
technology, the advancements in manned
aerial survey and how these stack up
against each other.
The belief that RPAS are a far more
cost effective solution stems from a few
factors. There is a lot of misinformation
across the spatial industry about the
capability and cost of RPAS systems, as
well as an overestimation of manned
survey costs. A large proportion of the
costs of running unmanned aircraft are
hidden or not immediately felt.
In contrast, the main cost in manned
survey—the running of the aircraft—is
immediately obvious. Usually the cost
comparison used by the drone industry is
based on a large format mapping camera
carried by a large twin engine aircraft,
capturing a small project area of 1 square
km or less. There is also usually a good
dollop of aircraft transportation cost
thrown in. The quoted cost for capture
with an aircraft, therefore, usually runs in
the tens of thousands.
Conveniently, comparisons between
the two technologies also choose a site
that the UAV is actually able to fly over,
ignoring the large parts of Australia where
these systems cannot legally or practically
be operated. This perpetuates what I call
the ‘expensive aircraft myth.’
Truth is, traditional large format mapping
cameras have never been cost effective on
small projects. To be fair, they were not
designed for this purpose. High capital
and operating costs associated with these
cameras mean that operation of these
systems are highly geared, and far more
suited to capturing large areas like entire
capital cities or local government areas.
Due to the recent evolution of large
swath sensors like the VisionMap A3,
Vexcel UltraCam Eagle (340 megapixels),
and custom multi camera sensors of
Nearmap and Spookfish, large format
aerial imagery has never been more
economical. This is especially true in
large urban areas where there is fierce
competition between providers like
AAM, Aerometrex, Nearmap and, soon,
Spookfish. Reduction in the rate per
hectare costs of imagery has driven the
demand for an increase in the temporal
resolution. As a result, repeated data
capture 2-4 times per year is now
A new medium [format]
While large format mapping cameras
cannot compete with drones on smaller
projects, a new generation of smaller
airborne sensors can, and do, offer a real
alternative on just about any project.
Often ignored by the RPAS industry is
the new generation of small and medium
format digital cameras, with sensors
ranging from 36 up to 100 megapixels.
To put this into perspective, the first
large format digital mapping cameras
from Vexcel UCD and Intergraph DMC
were about 86 megapixels, weighed about
200kg, and cost between AUD$1-2 million.
On top of this, they required specialised
survey aircraft costing around $1,600-
$2,000 per hour to run.
In the space of just ten years, however,
the capital operational costs of manned
sensors has decreased dramatically.
The new Hasselblad A6D medium
format aerial camera has 100 megapixel
resolution, weighs around 3kg, costs
around $50K ready to fly, and it can be
flown in a small single engine aircraft
costing $220-350 per hour to run.
While medium format digital cameras
boast impressive resolutions, spending
$50-150K for a ready to fly system is still
a serious investment. This is where low
cost small format (COTS) cameras like
DSLRs are now coming into their own.
Cameras like the Nikon D810 and Canon
EOS 5D Mark II are 36 and 50 megapixels
respectively, and both cost under $4K.
22 position August/September 2017
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