UNMANNED AERIAL VEHICLE TECHNOLOGY FOR LOW COST LANDSLIDE MAPPING

UNMANNED AERIAL VEHICLE TECHNOLOGY FOR LOW COST LANDSLIDE MAPPING Khairul Nizam Tahar *1, Anuar Ahmad #2 & Wan Abdul Aziz Wan Mohd Akib #2 *1 Departm...
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UNMANNED AERIAL VEHICLE TECHNOLOGY FOR LOW COST LANDSLIDE MAPPING Khairul Nizam Tahar *1, Anuar Ahmad #2 & Wan Abdul Aziz Wan Mohd Akib #2 *1

Department of Surveying Science & Geomatics, Faculty of Architecture, Planning & Surveying Universiti Teknologi MARA 40450 Shah Alam, Selangor, MALAYSIA #2

Faculty of Geoinformation & Real Estate Universiti Teknologi Malaysia 81310 Johor Bahru, Johor, MALAYSIA

email: [email protected] [email protected]; [email protected]

Abstract Landslide tragedy always occurred at the slope area or unstable ground. It is because of the changes of ground movement speed at shot period. Landslide can be affected by surrounding development for example cutting slope, highway construction or housing development. The development in an area has shifted a natural movement of the ground in the area. There are many factors that caused landslide. One of the main factor of landslide is underground water that flow at the unstable ground. Many research have been carried out to overcome this problem such as prediction of landslide, mapping of landslide risk area and in situ measurement at the prone area of landslide. Recently, Unmanned Aerial Vehicle (UAV) technology is becoming more useful to solve problem in many applications. The aim of this study is to generate three dimensional model using UAV images for landslide mapping. This study uses UAV technology for mapping area of interest. There are two types of UAV units that can be used for mapping purpose namely fixed-wing and rotor-wing. Rotary-wing UAV needs more time to stable before it can captured images on the ground. There are many kinds of rotary wing UAV that have been produced according to its specific application or needs. Unlike rotary-wing UAV, the fixed-wing UAVs are more stable and able to capture image easily. It allows remote control UAV to be practiced in any environment and urban mapping. UAV is capable to capture aerial images from certain flying height. The concept of UAV is the same as manned aerial vehicle but it needs a professional person to operate the UAV from the ground. In this study, the UAV images were processed using photogrammetry technique. Therefore, controls points were established before capturing digital images using UAV. The raw images were processed using image processing software in order to create digital elevation of the study area. The result of digital elevation model was used to create three dimensional model of a simulated landslide area. This study investigates contour line behavior of landslide area and performs calculation of area and volume at the landslide area. Orthophoto of the simulated landslide area was successfully produced after executing photogrammetric processes. The process includes the basic concept such as establishing ground control point and carried out certain orientations. Finally, the three dimensional models were used to automatically calculate volume of landslide area, calculate the direction and magnitude of landslide, calculate area of landslide and represent 3D model of

landslide area such as digital terrain model (DTM) using appropriate software. Based on the results of this study, it is useful for are many applications such as urban planning, data infrastructure of landslide risk area, forestry mapping, river surveillance and flood surveillance. UAV technology can be used in mapping applications but it needs some modification from certain aspect in order to fulfill requirement of mapping. The procedures involved in this study can be used by public work department for the purpose of monitoring landslide area with low cost budget, less manpower and fast results could be obtained. Keywords: Landslide, UAV, Photogrammetry, Orthophoto, DTM, 3D model 1 INTRODUCTION Photogrammetry is the art, science and technology which involve several processes of physical object or certain areas in order to acquire information about feature on the earth surface (Wolf & Dewitt, 2004). Data acquisition for aerial photogrammetry covers kites, gliders, balloon, airship, rotary and fixed wing UAV with the various flight modes such as manual, semi-automated or fully-automated. The methods of data acquisition depend on project budget, time of project and level of accuracy that is required in the project. The first UAV was developed by US military for surveillance purpose. Military used UAV in surveillance because it is small, quite and low risk at the enemy areas. Most of UAV has been attached with camera in order to captured images or video recording at the certain location (Lin, 2008). Tahar and Ahmad (2011) successfully used a rotary wing UAV and aerial photogrammetric technique for mapping simulated model to generate DTM and orthophoto. Nowadays, the idea of UAV has been widely used by civilian for hobby purposes. There are many kind of UAV that are available in market. According to unmanned vehicle systems international association, UAV can be categorized into 15 classes based on different mass, range, flight altitude and endurance of the UAV itself. Table 1: UAV categories (UVSIA, 2010)

µ Micro (µ) Mini Mini CR Close Range SR Short Range MR Medium Range MRE MR Endurance LADP Low Alt. Deep Penetration LALE Low Alt. Long Endurance MALE Medium Alt. Long Endur. HALE High Alt. Long Endur. Strato Stratospheric EXO Exo-stratospheric UCAV Unmanned combat LET Lethal DEC Decoys *TBD= To Be Dertermined

Mass < 5 kg < 25/30/150* 25-150 50-250 150-500 500-1500 250-2500 15-25 1000-1500 2500-5000 >2500 TBD >1000 TBD 150-500

Range < 10 km < 10 10-30 30 - 70 70 - 200 > 500 > 250 > 500 > 500 > 2000 > 2000 TBD >+/- 1500 300 0 - 500

Flight Alt. 250 m 150/250/300* 3.000 3.000 5.000 8.000 50 – 9.000 3.000 5/8.000 20.000 >20.000 >30.500 12.000 4.000 50 – 5.000

Endurance 1 hour 24 24 - 48 24 - 48 > 48 TBD +/- 2 3-4

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