Home' Position : Position 90 Aug-Spt 2017 Contents my experience, there is a reasonably high
attrition rate due to a mix of dumb thumbs,
equipment failure and human error.
A major disadvantage of capturing
projects with RPAS is that even simple
projects like a 50km corridor project of a
pipeline, rail or coastline quickly becomes
a logistical headache. Assuming that our
corridor project can be flown by a RPAS
and does not pass through populated
areas, over roads, or close to airports,
RPAS are still subject to additional
problems. These include: line of sight
restrictions, site-specific safety measures,
safely transporting high capacity LiPo
batteries, road access, bird strikes, sun
angle constraints and equipment failures.
Just planning an operation like this is a
small project in itself.
It may surprise some people how much
even a small electric drone actually costs
per hour to run. While it may only cost a
few cents of electricity to charge a battery,
it is all the other associated costs that
quickly add up: pilot and observer wages,
travel, accommodation, data processing,
staff training, vehicle costs and required
A mapping pod on a manned aircraft,
on the other hand, has an immediate
running cost of $350-400 per hour, which
includes wet hire (fuel included) of the
aircraft and pilot. Such a setup can
capture up to 10 square km an hour- a feat
that may take a drone crew multiple days.
In contrast, the wages alone of a UAV
crew with pilot and observer may total
somewhere between $100-200 per hour.
And the winner is...
Sorry to disappoint, but there is no
overall winner here. Unlike what the
slick marketing people would have you
believe, there is no one magic system. The
right system depends on the amount of
work you have in the pipeline, the type
of projects, location, size and required
deliverables. Both RPAS and manned
systems, therefore have their strengths.
It is hard to beat small RPAS systems
for small greenfield projects, especially
where you have existing boots on the
ground. It’s also pretty much only RPAS
systems that can deliver super high
resolution at 3cm GSD or better. However,
as project site size increases, or there are
multiple sites, then the advantage tends
to swing towards manned systems like the
portable mapping systems.
I realise that within the spatial industry
there seem to be people from both camps
with the blinkers firmly on for their
preferred technology. I don’t see manned
and unmanned platforms competing
against one another. Instead, I see them as
Both manned and unmanned systems
share similar sensors and post-processing
workflows. So adding manned surveys
to existing drone operations is a natural
extension. Smart operators are doing just
this. I already know of an example where
a portable mapping pod is used once a
month to map a mine’s active mining area
of about 40 square km. RPAS are then
flown on a daily basis over smaller areas
of interest and the data is fused with the
monthly manned capture. Both systems
are being used where they are the most
cost effective. I believe that this approach
is the future.
Erron Gardner is co-founder and
director of Aerial Acquisitions, an
Australian aerial survey firm using both
manned and unmanned platforms. He
also teaches RPAS surveying courses. ■
When looking at accuracy of a system,
be sure not to confuse the platform
specifications with those of the sensor. In
the RPAS sector most of the advertising
tends to highlight the platform’s
capabilities, like flight time, rather than
the all-important payload.
Low-end RPAS tend to use non-metric
sensors, including point and shoot
cameras, and integrated cameras like
those found in the DJI Phantom. While
suitable to produce orthophotos, unstable
camera geometry means they may not be
the best option for digital surface creation.
Unmanned systems flying at a legal
height of 400ft will also quickly run into
problems with image footprints. As flying
height decreases, image footprints also
decrease, which in certain environments
may cause tie-points to fail or create errors
in surface modelling.
Unmanned systems do have an advantage
over manned platforms when it comes
to the ability to capture extremely high
resolution imagery. Low cruise speeds,
especially from multi-rotor platforms,
allow imagery to be captured at 1-3cm
ground sampling distance (GSD). Manned
platforms at best achieve around 3cm
GSD for small sites, with projects more
commonly in the 5-15cm range.
Higher resolution is not necessarily a
good thing. The restricted flying height
means most drone projects are captured at
a higher resolution than they need to be,
adding considerable data processing costs
in terms of time and computing resources.
Unlike in manned aviation, it’s fair to say
that the number of crashes and incidents
in the drone industry are underreported.
Researchers like Dr Graham Wild from
RMIT are also of the opinion that far more
incidents occur than are actually reported.
On a professional level, I have heard stories
from a range of colleagues of drones
crashing, or flying off into the sunset. In
system can be fitted to
a range of light aircraft.
1. Vexcel UltraCam Eagle
2. VisionMap A3 Edge
3. Hasselblad A6D
4. Canon EOS 5D Mark II
5. Nikon D810
24 position August/September 2017
Links Archive Position 89 Jun-Jul 2017 Position 91 Oct-Nov 2017 Navigation Previous Page Next Page