Sauerbier and Eisenbeiss (2010) proposed the use of
UAVs
and photogrammetric techniques for documenting excavations
in archaeology under the assumption that inventories are
suitable and necessary, because objects continuously change.
Three case studies were documented: (a) large archaeologi-
cal site in Bhutan, explored by a quad-copter with
TOW
of up
to 5 kg; (b) excavation of a smaller site in the Nasca region in
Peru, containing ancient tombs with uncovered objects, with
a helicopter; and (c) a Maya site of Copán in Honduras, using
a helicopter with petrol engine, payload of 5 kg and main
rotor of 2 m. Photogrammetric techniques were applied in (a)
and (c) for 3
D
modeling of buildings and their remains. In (b)
only the aerial images are directly analyzed. Later, the same
authors in Eisenbeiss and Sauerbier (2011) reported about the
use of similar
UAVs
platforms in the Bhutan and Honduras
sites plus two additional sites in Pinchango Alto and Pernil
Alto in Peru. Commercial cameras were the sensors used.
Chiabrando
et al.
(2011) applied computer vision-based
techniques, including ortho-rectification, to build
DSMs
in two
archaeological sites of the Piedmont region in Italy. Two
UAVs
,
both equipped with commercial cameras, were tested for this
type of works: (a) helicopter in the Reggia di Venaria Reale
site; and (b) fixed-wing plane in the Augusta Bagiennorum.
Mosaics,
DSMs
, and overlaid contours based on
RGB
com-
mercial digital cameras were obtained in Remondino
et al
.
(2011) in two archaeological areas: (a) Veio and Pava (Italy)
with a quad-rotor, and (b) a Maya site in Copan (Honduras)
with an unmanned helicopter.
Mészáros (2011) used a fixed wing
UAV
, with 1.8 m wing-
span and weight of 0.9 kg, equipped with a
RGB
commercial
pocket camera (37 g) for ortho-mosaic generation in an undis-
covered archaeological site, signed by a crop-mark in moun-
tain Pilis, Hungary.
Grün
et al.
(2012)
integrated images of different resolutions
(satellite,
UAV
, and terrestrial) to obtain a textured 3
D
model
(DTM) of the Buddhist fortress Drapham Dzong located in the
Bumthang District, Bhutan.
Mozas-Calvache
et al.
(2012) proposed a method for pho-
togrammetric survey with a tethered helium balloon (2.5 m
diameter) in an archaeological site from the Tartessic epoch
in Southern Spain. They considered the undesired effects
produced in the photography acquired by these platforms
derived from uncontrolled factors, such as wind or lack of
flight control.
Brutto
et al
. (2012) presented
DSMs
and ortho-images re-
sults of the survey of the archaeological site of Himera in Sic-
ily (Italy), from images obtained through a quad-copter with
load capacity of 0.2 kg, weight 0.9 kg, and diameter of 70 cm
equipped with a commercial camera with a
CCD
of 7.6 mm ×
5.7 mm. In addition,
DSMs
and ortho-images were used in Rin-
audo
et al.
(2012) and tested on a Roman villa archaeological
site located in Aquileia (Italy), a well-known
UNESCO
World
Heritage list site. A hexa-copter, weighing approximately 650
g and maximum payload of 1 kg, equipped with a visible
CMOS
sensor was used. The same products were obtained
with a quad-rotor (700 g of payload) in Seitz and Altenbach
(2011) in two sites: (a) the excavation of a wooden Roman fort
in Neuhofen, Germany; and (b) the Daramsala, “House of the
Guests” in Banteay Chhmar, Cambodia.
Different thermal (FLIR-based) and
RGB
images are used
in Brumana
et al.
(2013) for documenting the archaeological
site of Isola Comacina (Comacina Island), in the Lago di Como
(Italy) where rock structures partially buried were studied.
The
UAV
is an octo-copter, size of 70 cm × 60 cm, and weight
of 2 kg. A
FLIR
sensor was used in Poirier
et al.
(2013) for the
detection of archaeological buried structures onboard an octo-
copter with wingspan of about 80 cm and payload of 3 kg.
Fiorillo
et al.
(2013) developed reality-based 3
D
digital
models and ortho-images of the archaeological area of Paestum,
Italy. They integrated 3
D
recording techniques, photogrammetry,
and terrestrial laser scanner techniques. A quad-rotor was used
for the acquisition of aerial images with payload of 1.2 kg and
equipped with a commercial color camera.
Casana
et al.
(2014) described a technique based on
thermography for discovering undocumented architectural
remains in the subsurface at the Chaco-era Blue J Community,
New Mexico. The
UAV
was an octo-copter that can lift around
2 kg of payload, with cameras mounted on an independently
operated gimbal suspended below the
UAV
. The gimbal is ca-
pable of a full 360º of motion, enabling cameras to be pointed
in a predetermined direction or at a specific point regardless
of the motion of the
UAV
.
Wildlife Conservation, Inventories, and Monitoring
Conservation and preserving ecosystems where wildlife exists
is a crucial issue. The use of
UAVs
for this purpose has at-
tracted the interest of researchers for several years. More than
a decade ago, Jones
et al.
(2006) studied during 2002 and 2003
the use of a 1.5 m wingspan
UAV
equipped with autonomous
control and video equipment to test the potential usefulness of
such an aircraft for wildlife research applications in Florida.
Chabot (2013) studied specifications and features of an
UAV
for wildlife monitoring and survey applications. In sensitive
ecosystems, they avoid having to walk the terrain, leading
to severe damage, with footprints or ground vehicle tracks.
Biologists have an excellent tool for many of their activities,
where specific designs of
UAVs
have been considered (Schiff-
man, 2014; Humle, 2014; Luo, 2014). Kite aerial photography
has been used in intertidal ecosystems for mapping of plants
(micro-and macro-algae) and animals (gastropods) assemblag-
es at different spatial and temporal scales (Bryson
et al.
, 2013).
From the remote sensing point of view, two main topics are
addressed for wildlife inventories and monitoring, specifi-
cally: fauna and flora.
Fauna
Large terrestrial and marine animals (elephants, rhinoceros,
bison, lions, sea lions, manatees, dugongs, bears, deer, foxes, or
whales) and bird colonies (geese, gulls) have been surveyed and
monitored using
UAVs
. An important role played by
UAVs
is that
of “aerial guardians” for the prevention of poaching. Currently,
major efforts are being made in this regard, particularly for
wildlife conservation (Yeld, 2013) and illegal fishing activities.
Large herbivores were monitored in the Gonarezhou Na-
tional Park in Zimbabwe, with the plan of studying trends,
behaviors, and changes in their populations Dunham (2012).
Elephants have been monitored and surveyed in Burkina
Faso with
UAVs
, where the aim consisted in determining
UAV
system’s parameters (maximum altitude for discrimi-
nation, camera system geometry) for discriminating single
animals or groups at the same time the animal’s behavior was
studied when the
UAV
flies above (Vermeulen
et al.
, 2013).
The
UAV
was a wing fixed system (catapulted through an
elastic launcher) with wingspan of 100 cm and weight 2 kg,
equipped with a commercial still digital camera. Prevention
of elephant deaths by trains is to be addressed by using
UAVs
for tracking their movements with the aim of alerting the train
drivers (Bala, 2014).
A fixed-wing
UAV
(
RPA
) with wingspan of 1,960 mm and
a maximum take-off weight of 2 kg with a 350 g payload
equipped with radio control and three different types of cam-
eras (still, video, and thermal) was used to verify its ability for
rhinoceros anti-poaching tasks in cooperation with security
companies working in the KwaZulu-Natal province of South
Africa (Mulero-Pázmány
et al.
, 2014).
Wilkinson (2007) described different methods for image
georeferencing, acquired from
UAVs
, with the aim of invento-
ries of bison as part of the wildlife.
308
April 2015
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
