Application of unmanned aerial vehicles (UAV) for - Skogsstyrelsen

96 Pages·2014·9.51 MB·English

by  Eugene Lopatin

B altic landscape – innovative approaches

towards sustainable forested landscapes

Application of unmanned aerial vehicles (UAV) for

landscape inventory

Authors: Eugene Lopatin, Alpo Hassinen

MRaerpjao rKt oNlost.r2ö5m, 2 014

Work Package 4
Date: May 2014

Authors: Eugene Lopatin, Alpo Hassinen

Partner organisation: University of Eastern Finland

Photographs: 1 photo on cover page by Alpo Hassinen

Corresponding author: [email protected]

www.baltic-landscape.net
Contents

Abstract .......................................................................... 1
Experience of using UAV in Finland .......................... 2
What is a UAV? ............................................................. 2
A UAV in short ............................................................... 2
The good and the bad of UAVs .................................. 3
UAV, aerial and satellite pictures ............................... 3
Applications for UAVs .................................................. 6
Landscape photographs .............................................. 6
Natural resources ......................................................... 7
Surveillance, inspection and search .......................... 8
Metrics and mapping .................................................... 9
Hobbies and movies ................................................... 10
Aviation rules ............................................................... 11
Airspace, other air traffic and limitations ................. 11
Aerial photography and legislation ........................... 17
Protected areas ........................................................... 17
Sanctity of the home and privacy protection .......... 17
Copyright ...................................................................... 18
UAS system ................................................................. 19
Commercial UAS systems ........................................ 20
Autopilot ....................................................................... 21
Equipment alternatives .............................................. 22
Telemetry ..................................................................... 22
Getting to grips with flying a new UAV .................... 24
Errors ............................................................................ 27
UAVs............................................................................. 31
Manufacturing materials ............................................ 32
Motor and controller ................................................... 33
Propeller type .............................................................. 34
Balancing the propeller .............................................. 36
Batteries ....................................................................... 37
Servos .......................................................................... 39
Radio control ............................................................... 39
Parachute..................................................................... 40
UAV alternatives ......................................................... 41
Cameras....................................................................... 41
Triggering the camera ................................................ 44
Camera stabilisation ................................................... 46
Recording video .......................................................... 46
Allowed radio frequencies ......................................... 47
Calibrating the computer screen .............................. 47
Flight operations ......................................................... 48
Flying ............................................................................ 51
Post flight ..................................................................... 53
Processing aerial photographs ................................. 53
Orthophotograph manipulation software and services 54
Common mistakes ...................................................... 57
Takeoff and landing spots ......................................... 57
Out of power ................................................................ 60
Technical faults ........................................................... 60
Human error and negligence .................................... 61
UAV data processing for assessment of energy biomass resources 62
1. Introduction .............................................. 62
1.1. Application of UAV for biomass inventory 63
1.2. Aims of the study .................................... 65
2. Data .......................................................... 66
2.1. UAV data .................................................. 66
2.2. Field measurements ............................... 70
3. Methods ................................................... 71
4. Results ..................................................... 74
4.1. Three-dimensional landscape model... 74
4.2. Biomass distribution within the landscape 77
4.3. Common reed biomass .......................... 79
4.4. Forest biomass........................................ 80
4.5. Accuracy of forest and reed biomass resources assessment based on data from
unmanned aerial vehicles ......................................... 81
4.6. Speed and efficiency of the UAV-based biomass assessment 84
5. Discussion................................................ 85
6. References .............................................. 89
Abstract
This report describes using Unmanned Aerial Vehicles (UAV) in Finland for landscape inventory.
The technical issue of applying UAV in practice is presented from the end user’s point of view. The
method for energy biomass mapping in landscapes using high resolution remote sensing data from
a UAV was developed and is presented. Using this method it was possible to develop an accurate
three-dimensional model of the biomass distribution within the landscape. The error in height
measurements of common reed plants and forest trees was 0.044 m. The error in common reed
biomass measurements using the UAV data obtained was 0.096 m3.
1
Experience of using UAV in Finland
Alpo Hassinen
What is a UAV?
A UAV (Unmanned Aerial Vehicle) is a flying device that can fly a pre-set course with the help of an
autopilot and GPS coordinates. The device also has normal radio controls; it can be piloted
manually in case of a fault or dangerous situation. Sometimes the term UAV is used to refer to the
complete system, including ground stations and video systems, however the term is most
commonly used for model planes and helicopters with both fixed and rotary wings. This paper uses
the term to refer to model planes.

A UAV in short
 The maximum flight altitude is 150 meters and the plane must remain in sight at all times
(with regulations due to become even more strict soon).
 The maximum weight is 20 kg.
 The plane must have radio controls so that it can be manually piloted away from other
aviators.
 Pictures taken with planes are sharper than regular air photos.
 The planes are quite reliable, but it is not recommended to fly above populated areas.
 These planes are not foolproof - there will be a crash within the first 20 takeoffs and
landings!
 It may be tricky to find a take-off place near the filming location.
 Photographs cannot be taken in a wind of over 5 m/s, during rain or in cold weather. This
means there will not be many flight days.
 It is recommended that a professional buys a tested system that is ready to use. The price
is €7,000 - 60,000 with maintenance and repair costs on top.
 The planes are not for the faint hearted - sweat will be dripping off your forehead when a
€60,000 plane is airborne.
2
 Hobbyists can buy an open source autopilot for €200 - 300 but a plane, radio controls,
batteries, chargers etc. are also needed. The total cost will be €600 - 2,000, but there will be
a lot of tinkering and building to do.
 It is good to start with a flight simulator and learn the radio controls.
 Good guides on radio controlled planes can be found at
www.kuopionlennokkikerho.net/opas.php
 The link list for this paper can be found at http://mekri.uef.fi/uav/uavlinkit.htm
The good and the bad of UAVs
A UAV is well suited for landscape photography and detailed photography of small areas, and also
video recording at low altitudes. It is easy and quick to take photos in the right weather e.g. when
the sun is shining from the right angle. The plane or helicopter can be transported in the boot of a
sedan car, and it is easy to take it to a suitable starting place.
Aviation rules lay down quite a few restrictions regarding the use of UAVs. The plane can be piloted
in uncontrolled airspaces without separate permission, however in controlled airspaces permission
from air traffic control is needed. Permission can usually be obtained simply by making a phone
call. Regulations require that the maximum flight altitude of the UAV is 150 meters, and the plane
should always be within sight. The new Aviation Act will make the rules stricter: the maximum flight
altitude will be limited to 120 meters and the maximum distance will be 500 meters. This Act
virtually prevents using a UAV for aerial photography of forests or for checking power lines. There
are a few loopholes to these rules; however more on that later.
UAV, aerial and satellite pictures
Satellite pictures are good for mapping, however in practice it is hard to buy fresh satellite photos.
Photography companies have large orders from around the world and they are not that interested in
photographing a small spot in far-away Finland. Satellite paths and clouds present their own
limitations; when the satellite is in the right place, there may be a cloud covering the area. The
resolution of satellite pictures is only 20-50 cm/pixel.
3
Mekrijärvi research station in a satellite picture by Google (Source: http://maps.google.com)

4
Pictures taken from an airplane are significantly sharper. The aerial photos available in Finland are
up to a few years old. These pictures can most easily be found from Paikkatietoikkuna or
Kansalaisen karttapaikka, for example. Your own photos can be ordered, but their prices range
from thousands to even tens of thousands of euros, and the timing depends on the weather and
other orders on the photography company’s to do list. The resolution of aerial photographs is
approximately 10 cm/pixel.
Mekrijärvi research
station in a picture by
Paikkatietoikkuna
(Source:
www.paikkatieto
ikkuna.fi/web/fi/kartta)

The resolution of aerial pictures taken by a UAV is 1 to 4 cm/pixel, and that is why they are best
suited for research and measurements. A significantly lower resolution suffices for mapping. Big
areas must be seamed together from several small pictures. This can be a complicated and
laborious task.
This picture is reduced significantly and it was taken at an altitude of 109 meters. People walking in
the yard can be seen in the picture. (Mekrijärvi research station)

5