International Scientific Conference May 26-27 2012 on Sustainable Development & Ecological Footprint Sopron, Hungary

Different Applications of Aerial Photography Using Radio

Controlled Model Airplanes

Sándor KALMÁR

Institute of Geology and Environmental Sciences, Faculty of Natural Sciences, University of West Hungary, Szombathely, Hungary

Abstract – The application of aerial photography has been widely used in the different research programs. The high costs of the research-specific airborne imaging technics and habitat-mapping is often beyond the budget of the research programs. Airborne images, made by radio controlled model airplanes provide a perfect alternative for the environmental and biological researches. The model airplanes give the possibility for landscape mapping or count field objects, which can’t be done with any other methods (or just with bigger efforts and disturbance). The presentation gives an overview of the application of the airborne imaging technics using radio controlled model airplanes or quadrocopters.

Keywords: aerial photography, radio controlled model airplane, quadrocopter, habitat-mapping,

1. INTRODUCTION

The interpretation of satellite or areial photos has become the most popular method to study certain types of habitats as well as perform different types of monitoring studies. For instance, satellite and aerial image interpretation plays a key role in the habitat mapping, measuring and counting performed in research studies or it is also used as a supplementary source of information for other works. However the airborne imaging techniques has some disadvantages in its practical use. For example, the relatively high cost of the research specific applications can prove to be prohibitive. Furthermore, the limitations of the piloted aircraft typically used must be considered in regards to their loud noise emissions, weather-dependance, high flight altitudes and high flight speeds that can effect the ability to use such a method.

Due to the above-mentioned factors, we developed a new technique: aerial imaging using radio controlled (RC) model planes and quadrocopters, can be applied not only to habitat mapping proposals but also to physical and geomorphological studies (KALMÁR 2008).

2. MODEL AIRPLANE

Model airplanes have been improved through the implementation of new technologies for a couple of decades. These technolgies include powerful brushless engines, lithyum polymer batteries, low weight and high strength raw materials or even digital flight-control instruments. Through their widespread adoption the cost of implementing these technologies has been reduced and their implementation has become more common place. These

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technologies have advanced model airplane capabilities to a level that they can meet the requirements for aerial imaging.

Fot the typical aerial imaging techniques it is ideal to use a middle-sized model airplanes with wingspans 2-3 m, and maximum 3 kg weight which do not require to have a relatively long runway and they are able to succesfully land on any kind of rough sufraces (Kalmár et al. 2008). The aircraft should be big enough to carry the different devices onboard. One could consider to increase the weight for more advanced cameras delivering high resolution images, but the result would be that one is no longer able to hand launch the vehicle.

Figure 1. The practical function of the airborne imaging system

(1: digital camera, 2: videocamera, 3: observed area,

4: pilot, 5: helper, 6: videoglass)

Figure 1 is showing the usage of the airborne imaging system. Onboard the model

airplane there is a high resolution, 10.2 mpx compact digital camera (1), which we can operate remote controlled, using a servo engine. Next to the digtal camera we placed a CCD video camera (2) as well, adjusted the same focus like the digital camera. Using a video transmitter it can send the live picture to a video glass (6) on the gound, which is worn by the helper (5). Helper can give guidance to the pilot (4) with the help of the online picture information, who can navigate the model right above the target objects. As the position of the plane is suitable for taking the pictures, the helper can operate the digital camera by remote control.

We developed a new model airplane (Figure 2) in the frame of the TÁMOP 4.2.1./B project, which has a 1.8 m wingspan, made by foam material, and has an electric engine in a pusher configuration. The electric engine guarantees a silent operation, and the pusher configuration allows its for the weight balance of the forward mounted payload. The empty weight of the model is 2 kg and it can lift 1.5 kg of payload. In addition, the power supply we are using is a 3 cell, 4300 mAh LiPo electric battery to allow 15-20 minutes of flight time during which the plane can reach a maximum of 600-700 m operational altitude. The lowest

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attainable flight speed can be acheived by flying against the wind, allowing the best conditions for taking pictures. The operating altitude should be choosen according to the requested scale of the objects being studied. The imaging system has an additional video transmitter that has a wireless connection to the ground station (Figure 2). As a resut this video transmission makes it possible to determine the field of view of the onboard camera. This method is very useful for making the best images of the requested objects.

Figure 2: The new model airplane equipped with camera and video-transmitter

3. QUADROCOPTER

Besides model aircraft we have also focused to the quadrocopters, also called as drones. The control of the drones is complex: the pilot can operate the vehicle in either radio control, GPS navigation, or gyroscope and preprogrammed flight track methods to guarantee the best navigation.

Figure 3. Quadrocopter before operation, with the reflex camera onboard

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Quadropters using a preprogrammed flight track method are able to follow speed and altitude specifications, GPS locations, and instructions on when to perform aerial imaging. During the operation the drone transfers all necessary information to the ground station: telemetry data (altitude, position, speed, distance from the basis) displayed on a map, technical and safety data (battery load, radio signal strength, wind speed, necessary time for returning), and the live video from the camera display.

The quadrocoper used in the TÁMOP 4.2.1./B program is a Microdrone md4-1000 (Figure 3), equipped with a high resolution (20 mpx) reflex camera, and a special compact thermocamera which can provie additional information relevant to geomprphological observations (Figure 4).

However, compared to model airplanes, quadrocopters are not able to carry as much payload, their equipment is more expensive, and they are sensitive to the extreme weather conditions (e.g., strong wind, etc). Consequently the specific requirements of a research study may result in the selection of either an airplane or a multicopter.

Figure 4. Aerial photos - using the quadrocopter - from the same reforestation sample area

using thermo-camera (left) and reflex camera (right).

Acknowledgement: This work was supported by the TÁMOP 4.2.1/B-09/1/KONV-2010-0006 project. References

KALMÁR, Sándor (2008): Mesterséges erdőfelújítás kisemlős közösségének szünbiológiai vizsgálata. Magyar Apróvad Közlemények 10: 221-309.

KALMÁR, Sándor - KOVÁCS Gyula - FARAGÓ Sándor (2008): Modellrepülős légifotózás lehetőségei biológiai kutatásokban. In: A Magyar Madártani és Természetvédelmi Egyesület VII. Tudományos Ülése. Eötvös József Főiskola Baja, 2008. október 24-26. Programfüzet: 14.