Land reflectance (bidirectional reflectance factor) has been
studied and different measures obtained in Hakala
et al.
(2010). The
UAV
is a quad-rotor with 55 cm from side-to-side
and payload around 300 g. A set of images were acquired with
a
CCD
commercial camera with weight of 200 g, from multiple
views for subsequent analysis.
A quad-copter equipped with a commercial digital camera
was used in Carvajal
et al.
(2011) to characterize landslides,
with sufficient accuracy, located on the size of a road in the
Abla municipality in Almeria, Spain.
In the context of temporal image analysis, object change de-
tection is the problem addressed in Shi
et al.
(2011) where an
area in Guangzhou, China was studied by applying image pro-
cessing and classification techniques including principal com-
ponent analysis, Mean-Shift, and K-Means. The georeferenced
images were acquired from an
UAV
. A time series analysis, over
four years, was used in Turner
et al.
(2015) for studying land-
slides dynamics from high-resolution images captured with
a
RGB
consumer-grade camera onboard an octo-copter (with
payload capacity of 2 kg). They applied
SfM
to create
DSMs
.
Niethammer
et al.
(2011 and 2012) used a quad-rotor
equipped with a digital camera for monitoring hazards in
areas affected by landslides (Super-Sauze landslide on the
north-face in the Barcelonnette Basin in Southern French
Alps), where temporal and spatial imaging changes are ana-
lyzed and
DTM
built for analysis. Landslide dynamics were
also investigated in Stumpf
et al.
(2012 and 2013) building
maps from images and also in Huang
et al.
(2011) for warn-
ing and emergency purposes in highway design in China.
SfM
was applied in Lucieer
et al.
(2014a) to obtain a 3
D
model of
a landslide in southeast of Tasmania based on multi-view im-
age frames obtained from an octo-copter with approximately
80 cm in diameter and
TOW
of 3 kg. It is equipped with an
autopilot, navigation-grade
GPS
receiver, and a commercial
standard camera. Rau
et al.
(2011) used a fixed-wing
UAV
with
3 kg of payload for landslide detection in Taiwan, equipped
with a consumer digital camera, a flight control computer,
a Garmin
GPS
receiver, and an attitude heading reference
system. An automatic algorithm was proposed based on the
object-based image analysis in advance and applying aerial
triangulation, ortho-image generation, and mosaicking. A
fixed-wing
UAV
with 2.4 m wingspan used in Lin
et al.
(2010)
for monitoring mountain hazards.
Soil monitoring was carried out in d’Oleire-Oltmanns
(2012) in the Souss Basin, Morocco in order to determine
the possible impact on soil erosion due to land leveling for
new land use. A fixed-wing aircraft with wingspan of 163
cm, length of 120 cm, and 2.3 kg of weight is employed; it is
equipped with a digital camera with 550 g.
Morillas
et al.
(2013) studied the surface energy balance
in Mediterranean dry-lands, considering soil and vegetation
components, and under water stress conditions. Part of this
study was carried out with an
UAV
, 2 m wingspan fixed-wing
with 5.8 kg
TOW
, equipped with a thermal camera with spec-
tral response in the range of 8 μm - 12 μm.
The identification of agricultural terraces was addressed in
Diaz-Varela
et al.
(2014) based on the assumption that these
areas are specific ecosystems. They applied a classification
approach based on the computation of ortho-rectified digital
surface models. The
UAV
carries a modified camera from
RGB
to
CIR
by removing the internal
NIR
filter. The
UAV
platform
is a 2 m wingspan fixed-wing platform with up to one-hour
endurance at 5.8 kg
TOW
.
Experimental analysis based on simulated rainfall and
gully mapping were conducted by Peter
et al.
(2014).
Haas
et al.
(2014) have integrated ground surveys for
textural and morphological patterns at an alluvial fan surface
through a lightweight (1.1 kg)
UAV
, with a wingspan of 1.2 m
and equipped with a
RGB
consumer-grade camera. The goal
was to study discharges and sediment-transport capacities to
estimate the efficiency of weathering and runoff.
SfM
was used
as a photogrammetric technique for subsequent
DEM
produc-
tion.
UAVs
imagery and georeferencing was applied in Barreiro
et al.
(2014) to obtain topographic information regarding the
runoff due to water flow during extreme rain events utilizing
photogrammetry. Simulation results defining how water can
flow into a close road was carried out.
Templeton
et al.
(2014) combined an environmental sen-
sor network and
UAV
-based imagery for studying hydrologic
processes in semiarid watersheds exhibiting a high degree of
spatial heterogeneity and seasonal evolution in land surface
characteristics from
DTMs
, derived from
UAV
images captured
with a consumer-grade camera.
As reported in Chen
et al.
(2014) the China Institute of
Geological Environment Monitoring conducted a research on
the characterization of the landslide at Daguangbao, which
was induced by the 2008 Wenchuan earthquake. The damage
pattern was analyzed by combining the pre-seismic remote
sensing image interpretation of QuickBird and SPOT5 satellite
imagery data, with post-seismic aerial imagery of the land-
slide area collected by airborne instrumentation in an
UAV
.
Geological structures of rocky surfaces at Piccaninny Point
on the east coast of Tasmania, Australia were studied in
Vasuki
et al.
(2014) for detecting faults, joints, and fractures
based on imaging analysis. Images were captured with a digi-
tal commercial camera onboard an octo-copter, where
SfM
is
the approach applied for 3
D
structure determination.
Soil erosion was also addressed by the
USGS
unmanned
aerial system program in
USGS
(2015b), more specifically
referred to monitoring the shoreline of the Missouri River on
the Lower Brule Reservation. Bioerosion, caused by burrow-
ing parrots on a cliff in Bahía Blanca (Argentina), was studied
in Genchi
et al.
(2015) using a hexa-copter to evaluate the
applicability of the 3
D
model based on
SfM
.
Aquatic Environments
Aquatic environments are of particular relevance in terms of
their protection and study because they generate ecosystems,
providing protection to different species of fauna and flora. In
this regard,
UAVs
were identified to play an important role. Ob-
servation of rivers for detecting water pollution and green algae
coverage or monitoring river boundaries, bridges, and coast-
lines is another relevant issue in such environments. Monitor-
ing of such spaces represents a high priority challenge to detect
changes in aquatic conditions for early response or monitoring.
Rathinam
et al.
(2007) used a fixed wing
UAV
equipped with
visible and
NIR
imagery collection systems for identifying and
mapping a river structure, including bridges. Liu
et al.
(2009)
developed an
UAV
equipped with multispectral imagery system
for quick-response when drinking-water pollution occurs. All
sensors are integrated onboard the
UAV
, and the CCD-based cam-
eras were calibrated and tested along a river. Wawrzyniak
et al.
(2013) used thermal imagery for water temperature prediction in
braided rivers. Flynn and Chapra (2014) used a
RGB
commercial
digital camera installed on a quad-rotor (with payload of 200 g)
to analyze the spatial and temporal distribution of filamentous
green algae on the Clark Fork River in western Montana.
Coastal areas in the Campania (Italy) have been scanned
in Lega and Napoli (2010) through a
FLIR
system onboard dif-
ferent platforms, including an ultra-light machine, a tethered
balloon, and two types of
UAV
: a conventional shape mini-
blimp and a Hybrid
LTA
(Lighter than Air) vehicle.
Fresh water wetlands areas were identified in Li
et al.
(2010) with an imaging system onboard of an airship, from
which different mosaics were produced.
Surveillance for tagging free drifting icebergs was proposed
by McGill
et al.
(2011) using video cameras, where the access
to hidden areas in the iceberg provides excellent potential for
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April 2015
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
