SEMINAR REPORT
ON
UTILIZATION OF DRONE TECHNOLOGY IN CIVIL ENGINEERING
Submitted to
NMAM INSTITUTE OF TECHNOLOGY, NITTE
(An Autonomous Institution under VTU, Belagavi)
In partial fulfillment of the requirements for the award of the
Degree of Master of Technology
in
Construction Technology
by
MOHAMMED PARVEEZ
4NM21CCT03
ACKNOWLEDGEMENT
1
Firstly, I thank my parents and friends who have directly or indirectly helped me to head
towards the development of this technical seminar.
I sincerely thank Visvesvaraya Technological University, Belagavi and NMAM
Institute of Technology, Nitte, India for providing excellent Infrastructure and
Academic Environment at NMAMIT without which this work would not have been
possible.
I am extremely thankful to Dr. NIRANJAN N CHIPLUNKAR., Principal, NMAMIT,
NITTE, for providing me the academic ambience and everlasting motivation to carry out
this work and shaping our careers.
I express my sincere gratitude to Dr. ARUNKUMAR BHAT., HOD, Dept. of Civil
Engineering, NMAMIT, Nitte, for his stimulating guidance, continuous encouragement
and motivation throughout the course of present work.
I also wish to extend my thanks to seminar Guide Mr. JANAKARAJ M., Assistant
Professor, Dept. of Civil, NMAMIT, Nitte, for the critical, insightful comments,
guidance and constructive suggestions to improve the quality of this work.
I would like to thank all the teaching and non- teaching staff of Dept. of Civil, for their
constant support.
Mohammed Parveez
2
ABSTRACT
An UNMANNED AERIAL VEHICLE (UAVs), also known as drone technology, is used for
different types of application in the civil engineering. Multirotor drones are considered a
new and innovative technology. Therefore, many fields are showing increasing interest in
utilizing multirotor drones, such as mapping in mining and surveillance in transportation.
Drones as a tools that increase communication between construction participants, improves
site safety, uses topographic measurements of large areas, with using principles of aerial
photogrammetry is possible to create buildings aerial surveying, bridges, roads, highways,
saves project time and costs, etc. however, multirotor drones have potential to facilitate
construction in many aspects. There is, therefore, a need to extensively research their
applications and analyse their roles in construction engineering and management. This report
aims to comprehensively investigate the current applications of multirotor drones, analyse
their benefits and explore their potential in the future of the construction industry. Several
main aspects are reviewed and discussed, namely land surveying, logistics, on-site
construction, maintenance and demolition. The results reveal that the main contributions are
work safety, cost-effectiveness and carbon emission reduction, while there are possible
adverse impacts on the basis of current limitations of multirotor drones. However, it can be
predicted that the usefulness of drones will continue to increase in the future of the
construction industry. Thus, this study will benefit construction managers in raising
awareness of the use of these emerging technologies and researchers in further exploring
applications of multirotor drones in construction projects.
3
TABLE OF CONTENTS
CHAPTER PAGE NO
1 INTRODUCTION 1
2 LITERATURE REVIEW 2
3 CLASSIFICATION OF DRONE 3
3.1 MULTIROTOR DRONE 3
3.2 FIXED WING DRONE 4
3.3 SINGLE ROTOR DRONE 5
3.4 FIXED WING HYBRID VTOL DRONES 5
4 CASE STUDY 6
5 NECESSITY OF DRONE 14
6 ADVANTAGE OF DRONE 15
7 DISADVANTAGE OF DRONE 15
8 FUTURE RECOMMENDATION 16
9 CONCLUSION 17
10 REFERENCE 18
4
INTRODUCTION
Drones are widely known under various names, such as UNMANNED AERIAL VEHICLE (UAVs),
UNMANNED AERIAL SYSTEM (UAS) and REMOTELY PILOTED VEHICLES (RPVs), etc. The
introduction of drones to the construction industry is recent, although their use in other areas of industry
(e.g., agriculture, public safety, military purposes, science and research, monitoring security, mining,
etc.) has been frequent. In the construction industry, aerial vehicles have been used for numerous
purposes; such as, inspection of highways, bridges, roads, cell towers, high mast lighting, wind turbines,
power transmission lines, building façade and roof, survey and mapping, construction monitoring,
wetland/environmental, drainage and erosion, traffic monitoring, emergency services, etc. UAVs provide
invaluable help and cost savings with wide views of inaccessible and otherwise difficult and tough to
navigate locations. UAVs indicate best access with the overhead perspective and 360° panoramas relay a
real-time scenario. Yet, expensive military drones are often not cost-effective alternative for many users
in civil application such as entertainment and transportation. Nowadays non-military drones have
allowed 3D high-quality mapping data to become much more accessible. Thus, drone technologies
enable better management and faster and more informed decision-making, and provide accurate high-
resolution archival records for various sites.
With this input, engineering teams can prioritize their approaches. Operators can share the imaging with
personnel on site, in company and also with sub-contractors at the distance. The data in terms of drone
images from multiple locations and point clouds (from 3D scanning of construction site) can be used to
construct a 3D model using the photogrammetry techniques. This so-called “drone model” can be
compared to BIM model at various construction stages to monitor the construction progress. Beside
construction scheduling and costing, this comparison can be expanded to include real-time recording,
reporting, billing, verification and planning. Digital tools and processes cannot replace people, either as
individuals or teams, but they are required to increase quality of work, reduce costs and safety risk,
improve decisions, reduce time-consuming processes, etc. Drones present increasingly attractive
opportunities for achieving these goals, e.g., a team of scientists has demonstrated that UAVs were able
to build a rope bridge, assemble items to create a structure, or detect and catch an object in the air. On the
present, UAVs offer a high level of automation that allows to reach previously inaccessible areas, while
capturing a large amount of data very quickly. However, this is not their only use.
5
Control of vehicle motion is achieved by varying the relative speed of each rotor to change the thrust and
torque produced by each. Drones can be manoeuvred in small spaces when hovering and can be controlled by
various devices such as tablets, laptops and desktop computers. They can also be easily equipped with
LIGHT DETECTION AND RANGING (LIDAR) instruments, cameras and communication devices.
Therefore, many fields are showing increasing interest in utilizing multirotor drones for v various non-
military purpose.
LITERATURE REVIEW
o In 2016 Harvey et al. Among these, multirotor drones like quad copters have distinct advantages
compared to other UAV systems, such as robustness, high manoeuvrability, and low purchase and
maintenance costs. Multirotor drones have more than two rotors and use fixed-pitch blades. Control
of vehicle motion is achieved by varying the relative speed of each rotor to change the thrust and
torque produced by each. Multirotor drones can be manoeuvred in small spaces when hovering and
can be controlled by various devices such as tablets, laptops and desktop computers. They can also
be easily equipped with LIGHT DETECTION AND RANGING (LIDAR) instruments, cameras and
communication devices.
o In 2017 Mesas Carrascosa et al., for forestry and agriculture management, to achieve site-specific
weed management, the ultra-high spatial and high spectral resolution imagery provided by multirotor
drones was used for weed mapping at very early stages of crop and weed plants.
o In 2017, it was used in emergency and disaster management, multirotor drones were applied to
search for and rescue people trapped by debris or injured during disasters, (Erdelj et al.).
o In 2016 Herrmann, the contemporary construction industry, multirotor drones as an innovative
technology have potential to facilitate construction activities from observation and inspection to
monitoring of safe practices, leading to savings in time, cost and injuries, along with quality work.
6
CLASSIFICATION OF DRONE
The best classification of drones can be made on the basis of aerial platforms. Based on the type of aerial
platform used, there are 4 major types of drones; fixed wing drones, multi rotor drones, single rotor
drones and fixed wing hybrid VTOL drones.
Multirotor Drone
Multi-rotor drones are the most commonly used types of drones, which are used not only for fun, but
also for professional aerial mapping. Common applications of multi rotors are aerial photography, video
recording and aerial surveying. These types of drones can be classified according to the number of
rotors, e.g., tricopters (3 rotors), quadcopters (4 rotors), hexacopters (6 rotors) and octocopters (8 rotors).
The disadvantage of multi-rotor drones is their limited endurance and speed. Due to these limitations,
these types of drones are not suitable for large scale aerial mapping, e.g. pipelines, roads, power lines,
highways, etc. Despite the drone technology continues to improve, multi-rotor drones have to do a lot of
effort to keep them in the air. Depending on the weight of the drone and camera, multirotor drones
currently hold an average of 20-30 minutes or less in the air.
Multi Rotor Drones
Fixed Wing Drone
Fixed wing drones operate essentially on the same principle as passenger airplanes. These drones do not
generate thrust by vertical rotors, but generate lift using fixed wings. These types of drones need energy
only to move forward and not to keep them in the air. For this reason, they are a much more efficient
variant for topographic mapping of large areas and they are able to cover longer distances than multi-
rotor drones.
On the other hand, the main disadvantage of the fixed wing drones is the inability to stay in the air in one
place, which prevents them from creating detailed aerial mapping, e.g. the as- built buildings. Another
disadvantage of this type of drone is its take-off from the ground and landing on the ground. Depending
7
on the size of the drone is necessary to have a runway or catapult launcher to get them into the air and on
the other hand is necessary to have a runway to get them to the ground back safely. The fixed wing
design allows these drones to reach a higher altitude during flight, making them efficient tool for aerial
mapping topography, but on the other hand they can only fly forward. For closer aerial work which
requiring more detailed activities, e.g., detailed aerial mapping of buildings, the use of multi- rotor drones
is a much better solution because they are easy to work with in the air and their rotor design allows them
to hover stable in the air.
Fixed Wing Drone
Single Rotor Drones
Multi-rotor drones generate vertical thrust using multiple rotors, but on the other hand a single
helicopter drone uses only one rotor. The single helicopters drones can be powered by gasoline engines
and thus last much longer in the air than multi-rotor drones. If it is necessary to fly with higher payload,
e.g. with the LIDAR scanner, or if it is necessary for aerial mapping to combine a long endurance of
the flight with forward flight, in this case a single helicopter drone is a good choice. The disadvantage
of this type of drone is the increased complexity, cost, vibration, and they also require more mechanical
maintenance due to their increased overall technical complexity.
Single Rotor Drone
8
Fixed Wing Hybrid VTOL Drones
Fixed wing unmanned aircraft is known to be more energy efficient than quadcopters and as a result can
cover long distances much faster. But quad-shaped drones do not need that much space for take-off and
landing. That is also why some manufacturers have decided to combine these characteristics and have
developed unmanned aircraft that can take off vertically and then go into horizontal flight using wings.
Their name is very similar to the automobile industry, and it, hybrid drones. The hybrid drone flies on a
pre-scheduled flight route at a user-specified height and collects data through its colour and
multispectral sensors. Upon completion of its mission, the drone will land vertically back to the starting
point.
Fixed Wing Hybrid Drones VTOL (vertical take-off and land)
CASE STUDY
Construction Land Surveying
First, consultation of topographic maps is essential. Topographic maps may reveal construction design
errors that are inappropriate for terrain. Although topographic maps are useful for construction projects,
their production is often costly and time consuming. The use of drones is very effective in these cases.
Traditional land surveying techniques require bulky tools, such as tripods, total stations and GSP
equipment. Multirotor drones equipped with cameras, autopilots and image processing software can
be applied to land surveying and mapping in construction projects for providing faster and less
costly land surveys.
The research of Siebert and Teizer (2014) compared two types of measurements, a manual, ground-
9
based, real-time kinematic GPS survey and a drone-based photogrammetric survey near the city of
Magdeburg, Germany. Figure below shows sketches a photogrammetric survey procedure for a
construction site. The left-bottom picture shows a plan view of a construction site and indicates a
flight path over the site. The right picture demonstrates that a camera mounted on the drone is
pointed down towards the ground to measure 3D dimensional coordinates. 3D models can be then
created by aerial photogrammetry. Compared with a traditional GPS survey that consists of 1800
individual points in the area of 60,000 m2, the drone-based photogrammetric survey approach is
capable of autonomously
collecting 5,500,000 colour-coded points and producing a result in the format of an orthophoto
(Siebert and Teizer 2014). The test demonstrated that the drone-based survey reduced the time to
one-third and increased the point density by more than 3000 times.
A drone-
based photogrammetric survey.
Time Management
Time management in addition to safety management and quality inspections, time management can
also be improved by drone-BIM technologies in construction projects. 3D BIM models can be
enhanced if linked with schedule (4D), costs (5D) and project lifecycle information (6D). And BIM
models have been applied in the field of construction progress monitoring by presenting multi-
dimensional data. Multirotor drones aim to efficiently collect records and as-built information, even
in indoor construction sites. BIM can be then updated to estimate whether the investigated events
will cause any delays and whether there could be other effects on normal progress.
Irizarry and Costa (2016) presented four cases to identify more potential applications of multirotor
drones during the construction process. The first project included demolition and reconstruction
10
work for an academic office building in the city of Atlanta, Georgia in the USA. The other two
projects were construction of an academic research building and a high
school building in Georgia. The last project was related to the construction of eight apartment
buildings in the city of Salvador, Bahia in Brazil. A total of 200 visual assets including 98 photos
and 102 videos were collected within a seven-month period through drone flights at the job sites.
After interviewing construction project personnel, the researchers and construction staff considered
that multirotor drones had potential applications in progress monitoring and planning for
construction management tasks, in addition to safety management and quality inspections.
BIM-LIDAR construction quality control system.
Thermal Imaging recording
Similar to laser scanners, also drones can be used to create aerial thermal images from different
parts of buildings which can be used to assess cold spots in buildings. This possibility can bring for
engineers, surveyors and contractors’ necessary information about the building in the case when is
essential to identify and rectify building defects, e.g. places where thermal bridges arise and the
like. Thermography allows determine thermal technical properties of building envelope and is used
to detect hidden building defects. Thermography is able to find these failures with the necessary
accuracy and, if evaluated correctly, is the basic step for effective design of the technical solution
and consequently also for checking
its realization. Combining thermography with drones allows detection of such construction defects
that are not visible to the naked eye.
Thermal imaging of the certain part of the building can also help detect water infiltration, leaks, and
11
areas with mold or rot before they cause serious damage. These cold, damp areas will appear as dark
blue on the thermal imaging screen. From the inspector’s standpoint, using the equipment to inspect
rooftops, pinpoint leaks and detect heat loss make the process simpler, safer and faster and generally
more efficient. Other uses of drones in the construction industry can be included security surveillance,
personnel safety, health and safety inductions, maintenance inspections, promotional photography, live
feed/ virtual walk around, site logistics, monitoring workers, etc.
Example of drone thermal imaging
Building Surveys
Almost every building survey of the building requires the visibility of the roof of the building in
order to assess its technical conditions and to assess any defects or failures. In most cases, the
ascent to the roof is complicated, which often requires the use of scaffolding, ladders or other
auxiliary structures, which may ultimately pose a danger which are both time consuming and
costly. Use of a small drone in these cases can save time, costs, reduce health and safety risks
which are connected with the building surveying of the roof structure and with accessing to
complex or hard to reach parts of the building’s roof. Looking in figure below it can be seen that
for overall aerial mapping of the building it is necessary to create vertical (left part of the figure)
and oblique (right part of the figure) aerial images. Vertical aerial photographic coverage of the
roof is normally taken as a series of overlapping flight strips. The overall time for automatic mode
was in this case 3 minutes and 100 aerial images were created. The oblique aerial images which
were focused on the building’s façade were created in the manual mode, it means, that this
12
process is about the pilot’s practical and personal experiences. In this mode, 950 aerial images
were created in the distance from the building approximately 10 – 15 meters in three altitude
levels. The comprehensive data collection time of aerial mapping was 2 hours and 1050 aerial
images were created.
Example of technological process of oblique (right) and aerial images of building
creating vertical (left)
Safety management
Construction safety management has been a popular issue in research and practice, as workers
are frequently exposed to fatal accidents in the construction industry. Initially investigated the
potential benefits of drone-related technologies for safety managers in the construction
industry. As multirotor drones are able to collect and deliver real-time videos of the current
situations at construction job sites, explored their applications in safety inspection on
construction job sites. An experiment was designed by the researchers to simulate a
construction job site. The inspection task of detecting whether or not workers were wearing
their hard hats was performed and visualized via different observation conditions, namely a
plain view, an iPad and an iPhone. The results revealed the practicability of multirotor drones
in safety management, showing that both plain view and iPad. A drone-based
photogrammetric survey procedure visualization conditions could provide satisfactory
accuracy in hard hat detection.
13
Construction Site Inspections
For builders the data from drones can be collected frequently allowing easy integration into
projects and tracking site progress precisely and with hardly any lag time. This allows
construction companies to work more effectively in managing their time and resources while
minimizing potential issues and delays. Construction site inspection using drones can be a
considerable tool for project teams. A pilot with experiences can use the drone to identify any
construction or technical problems on the construction site and also using drones for inspection
purposes is possible to ensure that the project goals will go according to plan. The use of drones
can save thousands of euros in the case of rebuilds and plan changes. Using drones can be much
safer as well because it eliminates spaces or areas on the construction site that could potentially be
dangerous to assess the damage. With more advanced technology, it is possible also use a drone
to fly around a construction site and check out how closely it resembles the construction plan or
the model, drones can aid in the creation of detailed 3D models of new construction projects,
drones can help to see what things look like on the roof of a skyscraper under construction, etc.
Drone due to its ability to perform visual inspection of high risk areas on the construction site or
on the new - exist building can save time, reduce health and safety risks. Aerial photographs can
be documented from the safety of the site cabin and then sent to project
team in HD quality very quickly and effectively. Site inspections can be undertaken more
regularly and cover larger areas more efficiently. There are four main benefits to using drones
for construction site inspections: improved safety saves time, less labour-intensive and higher
quality data.
14
Construction site inspection by a drone
Equipment Tracking and Automating
Equipment tracking and automating is the problem of every project manager on the
construction site. This is usually a problem with a large number of different tables and
documents, which are often difficult and time-consuming to keep. Using the drone, the same
project manager can immediately assess if the equipment is where it should be during the
drone flight. It is also possible to quickly assess with a drone if a devices that have already
completed its work is still on-site and with this solution is also possible to prevent expensive
accidental extension charges.
Remote Monitoring and Progress Reports
Probably the biggest advantage of drones in the construction industry they can provide to
clients is their visibility from the air, from a great height and from any location. A constant
drone flight on the construction site can represents a quick way to map the progress of a
project, especially when the clients are not able to be physically present on a site. Thanks to
multiple high-resolution aerial images and HD-quality videos, project developers can get a
better overview of project progress at daily, weekly or monthly interval. According to it’s
recommended to film only those areas of the new construction where the best progress is
achieved, unless the client stipulates otherwise
Integration of laser scanning and aerial photogrammetry
It is often difficult for a surveyor to gain access to a suitable laser scanning location from
which would be possible to scan, e.g. roof construction. In this case the final point cloud can
be incomplete. The drone technology in integration with the laser scanning can brings
solution of this limitation. Looking at figure below, it can be seen the reference building
where the technology of terrestrial laser scans and aerial photogrammetry using a drone were
used. The measurement of this building was divided into two stages. In the case of terrestrial
laser scanning (stage 1), the completely facade of the building was selected for digital
surveying, and in the case of aerial photogrammetry (stage 2) the completely roof of the
building was selected for digital surveying. The total data collection time of the first stage
15
was approximately 12 hours and together was created 48 scanner positions which were
focused on the exterior part of the building. The total data collection time of the second stage
was approximately 30 minutes (flight plan of the drone, aerial photographs in automatic
mode, and aerial photographs in manual mode) which were focused on the roof construction
of the building.
In the second phase, a total of 302 aerial photographs were taken using a DJI MAVIC PRO
quadcopter with a 12 Mpx digital camera, and the entire drone flight was performed with
one battery. The phase of data processing in this case consisted from three stages. The first
stage was primary focused on creation of two point cloud from two technologies using the
appropriate software’s. The second stage was about integration of two local coordinate
systems from two point clouds into common coordinate system. This was very important
step for the final connection of two point clouds. The last stage was about final connection of
two point clouds based on the common coordinate system. Data processing time for laser
scanning was 3 hours and the Faro Scene and Autodesk Recap software were used. Data
processing time for aerial photogrammetry was 31 hours and the “Agisoft Photoscan
Professional” was used. The final point cloud includes now all space information about the
building and this data can be used for either CAD or BIM modelling like a template for a new
as-built project.
Connection of terrestrial laser scanning and aerial photogrammetry
16
NECESSITY OF DRONE IN COSTRUCTION
Economic perspective
As in economic view, drone-based surveying approaches are relatively cost-effective. Multirotor
drones can achieve the rapid collection and automatic analysis of terrain data. Drones can also be
used to automate other simple tasks and significantly reduce project costs. Instead of using human
resources, heavy machinery and expensive surveying tools, drone-based technologies are capable
of producing complex data with less expense and greater accuracy. Structural
inspections often require typical inspection units, such as truck cranes, elevating platforms and
underbridge units. Drone-based inspection approaches can also avoid the high logistical and
personnel costs that large trucks, special elevating platforms and scaffolding require.
Furthermore, drone mapping is also unbeatable in terms of speed, compared with traditional
approaches to land surveying. Traditional land surveying may require long hours and carrying of
heavy equipment from one location to another. However, drone mapping may take only minutes
to complete a site survey with higher accuracy, instead of days or weeks. Similarly, timely
gathering of as-built status for construction sites also requires frequent and intensive surveying
resources. Drone-based progress monitoring can avoid delays in construction projects. A delay
to completion and delivery can result in extra costs and reduce profitability due to consequential
losses and expenses.
Social Perspective
From the social perspective, the main contribution of multirotor drones in construction is to
resolve work safety issues. For example, land surveyors usually work in a dangerous environment
due to highly sloped surfaces or being close to heavy equipment. Their work is always outdoors,
regardless of weather conditions. Having a drone-mapping solution allows for autonomous flights
to eliminate several risks associated with land surveying, such as heavy equipment and injury
from hazards. Drone-based technologies can also resolve the problems of difficult and dangerous
structural inspections, such as those of steep-sloped roofs, exterior facades and walls, towers and
bridges, damage due to fires and explosions, vehicle accidents and catastrophic events (Mat Yasin
et al. 2016). Furthermore, over time buildings change, this makes demolition work hazardous and
unpredictable. Predicting how buildings may fall can ensure a safe demolition environment via
17
simulation, in which 3D building models can be created through building thermal inspections
from drones. Overall, injury and fatality can be greatly reduced or avoided through the effective
use of multirotor drones.
ADVANTAGE OF DRONE
It provides bird’s eye view
It can provide photo video 3d rendering services
Can be used to inspect, manage, track site activity remotely
Traditional terrain survey requires manual acquisition of multiple GPS point, which
may be safe to do in some places, but using drone we can easily collect hundreds of
GPS points
DISADVANTAGE OF DRONE
Single rotor drone are complex and hard to fly compared multirotor drones
Fixed wing type of drone are hard and expensive to acquire. And require expert
person to fly
They have very low flight time of about 15-30 min depending on the type of
payload. Also it cannot equip heavy payloads
Weather and wind condition should be favourable to fly. Heavy wind can disrupt
flight
FUTURE RECOMENDATION
o Regularly updating the existing drone with the latest technology available.
o Pairing with latest equipment available.
o Pairing the drone with the evolving autonomous vehicle and equipment available.
CONCLUSION
Drones are an important technological asset in the area of civil engineering. Their use in the
construction industry will only increase in time because they can efficiently collect data of a
high standard, greatly minimizes risk to the safety of a project team. In general, the
construction industry is often careful in implementing new progressive technologies into
18
production or in established workflows. The construction industry can be described as a fast-
growing industry, and UNMANNED AERIAL VEHICLE technology was quickly adopted as
a tool that saves costs, time and increases safety and control. Construction companies receive
drones much faster than ever because of their innumerable benefits. Whether drones are used
by construction companies for topographic terrain mapping, building surveys, land surveys,
construction site inspections, remote monitoring, progress reports, thermal imaging recording
or for integration with laser scanners, drones have proved as invaluable tool throughout the
life cycle of a construction project. The drone capabilities enable them to save costs, time, risk
and labor, which automatically lead engineers, contractors, investors or future customers to
more confidence and certainty in working on a construction project.
REFERENCE
Harvey MC, Rowland JV, Luketina KM. 2016. Drone with thermal infrared camera
provides high resolution georeferenced imagery of the Waikite geothermal area, New
Zealand. J Volcanol Geothermal Res. 325:61–69.
Herrmann M. 2016. UNMANNED AERIAL VEHICLE in construction: an overview of
current and proposed rules. Construction Research Congress; May 31–Jun 2; San Juan,
Puerto Rico.
Mesas-Carrascosa FJ, Clavero Rumbao I, Torres-Sanchez J, Garcıa-Ferrer A, Pena JM,
Lopez Granados F. 2017. Accurate ortho-mosaicked six band multispectral UAV images as
affected by mission planning for precision agriculture proposes. Int J Remote Sens. 38(8–
10):2161–2176
Erdelj M, Krol M, Natalizio E. 2017. Wireless sensor networks and multi-UAV systems
for natural disaster management. Computer Networks. 124(4):72–86.
19
