Wan Abdul Aziz Wan Mohd Akib

UAV-based stereo vision for photogrammetric survey in aerial terrain mapping

Recently, Unmanned Aerial Vehicle (UAV) technology is becoming useful to solve problems in many applications. The aim of this study is to investigate the use of light weight rotary-wing UAV for mapping simulation model. The objective of this study is to determine the accuracy of the photogrammetric output. This study only concentrates on one type of rotor-wing UAV. It is because rotor-wing units are more stable and able to capture images easily. It allows remote control UAV to be practiced in any environment and urban mapping. In the simulation model, ground control points (GCP) and checked point (CP) were established using total station. The GCP is used in the photogrammetric processes to produce photogrammetric output while the CP is used for accuracy assessment. A Nikon Coolpix consumer digital camera was used for images acquisition of the simulation model where two methods were used. In the first method, the camera was mounted vertically in a rotary-wing UAV and captured the images at an altitude. In the second method, the camera is mounted vertically at a fixed height. The acquired images were processed using photogrammetric software to produce orthophoto and digital elevation model of the simulation model. From this study, it was found that root mean square errors for fixed platform are ±0.002m, ±0.001m, ±0.214m for coordinate x, y and z respectively while the root mean square errors for mobile platform are ±0.002m, ±0.002m, ±0.223m for coordinate x, y and z respectively. It can be concluded that the differences between the mobile and fixed platforms are not significant. In conclusion, UAV system can be used for large scale mapping for aerial terrain mapping.

Unmanned Aerial Vehicle Photogrammetric Results Using Different Real Time Kinematic Global Positioning System Approaches

This chapter describes photogrammetric results based on unmanned aerial vehicle (UAV) images for slope mapping. This chapter discussed the effect of photogrammetric results based on different observation time and network adjustment of Real Time Kinematic Global Positioning System (RTK GPS) in photogrammetric image processing. A complete set of fixed wing UAV with autonomous flight was used to capture image from certain altitude at the study area. All acquired images were processed using photogrammetric software. Two primary results were produced in this study namely digital elevation model and digital orthophoto. Analyses were carried out to determine the best RTK GPS data based on time and network during photogrammetric image processing. It was found that, RTK GPS adjustment from known point with 10 minutes observation time gives greater accuracy compared to the local network adjustment. In conclusion, UAV has potential in the slope mapping because it can provide high accuracy photogrammetric results.

A generic approach for photogrammetric survey using a six-rotor unmanned aerial vehicle

This paper discusses a rapid production of slope mapping using multi-rotor unmanned aerial vehicle (UAV). The objective of this study is to determine the accuracy of the photogrammetric results based on novel method of multi-rotor UAV images as well as to analyze the slope error distribution that are obtained from the UAV images. This study only concentrates on multi-rotor UAV which also known as Hexacopter. An operator can control the speed of multi-rotor UAV during flight mission. Several ground control points and checkpoints were established using Real Time Kinematic Global Positioning System (RTK- GPS) at the slope area. Ground control points were used in exterior orientation during image processing in sequence to transform image coordinates into local coordinate system. Checkpoints were established at the slope area for accuracy assessment. A digital camera, Sony NEX-5N was used for image acquisition of slope area from UAV platforms. The digital camera was mounted vertically at the bottom of UAV and captured the images at an altitude. All acquired images went through photogrammetric processing including interior orientation, exterior orientation and bundle adjustment using photogrammetric software. Photogrammetric results such as digital elevation model, and digital orthophoto including slope map were assessed. UAV is able to acquire data within short period of time with low budget compared to the previous methods such as satellite images and airborne laser scanner. Analysis on slope analysis and error distribution analysis are discussed in this paper to determine the quality of slope map in the area of interest. In summary, multi-rotor UAV is suited in slope mapping studies.

Prediction of Susceptible Areas of Future Earthquake Induced by Landslides in Padang Pariaman District, West Sumatera, Indonesia

The island of Sumatera sits on top of Southeast Asia’s tectonics plate, which overrides the sub-ducting Indian and Australian oceanic tectonic plates that convergence obliquely at about 50–60 mm/year. Based on the focal depth and dip angle, sub-duction zones are divided into interplate (megathrust) and intraplate (benioff) zones. Megathrust zone earthquake event occurs at a depth of less than 50 km and while benioff zone earthquake event occurs at a depth of 50–200 km. The earthquake is generally assumed to occur throughout the region and according to landslide experts, the tectonic plate in this megathrust zone produces major earthquakes every 200 years. The new 200 year cycle has predictably come in recent years. Therefore, based on the assumption of past and present landslides are keys to the future landslides. This means that future landslides will occur in similar geologic, geomorphic and hydrologic conditions. This assumption permits an estimation of future occurrences based on historical data of the earthquake with a 7.6 Richter Scale (RS) which struck Padang Pariaman District, West Sumatera Province, Indonesia on Wednesday, September 30, 2009 that caused 375 death buried by the landslides. Other factor such as geographical condition of West Sumatera Province that is normally triggered by earthquake caused landslide. The topography of this region is mountainous where the hills are easily fall down especially after earthquakes and heavy rain. These factors caused severe landslide. This paper predicts the increase of zonation of susceptible areas of major earthquakes occurrence in the future using remote sensing, GIS and calculation of peak ground acceleration (PGA) using global attenuations. The methods are implemented to generate GIS-based landslide susceptibility maps for Padang Pariaman District which include the use of remote sensing data to map existing landslide locations. Other factors that are important in landslide initiation include slope, slope aspect, elevation, land use/land cover, vegetation mass and mapping the ground acceleration map using global attenuations. The frequency ratio models are also used to map landslide susceptibility.

Analysis of debris flow Kuranji River in Padang city using rainfall data, remote sensing and geographic information system

Flash flood is the most common environmental hazard worldwide. This phenomenon is usually occurs due to intense and prolonged rainfall spells on saturated ground. When there is a rapid rise in water levels and high flow-velocities of the stream occur, the channel overflows and the result is a flash flood. Flash floods normally cause a dangerous wall of roaring water carrying rocks, mud and other debris. On Tuesday, July 24, 2012 at 18:00 pm, a flash flood (debris flow) struck Kuranji River whereby 19 urban villages in seven (7) sub-districts in the city of Padang were affected by this flood disaster. The temporary loss estimated is 40 Billion US Dollar reported by the West Sumatra Provincial Government due to many damages of the built environment infrastructures. This include damaged houses of 878 units, mosque 15 units, irrigation damaged 12 units, bridges 6 units, schools 2 units and health posts 1 unit. Generally, widely used methods for making a landslide study are Geographic Information System (GIS) and Remote Sensing techniques. The landslide information extracted from remotely sensed products is mainly related to morphology, vegetation and hydrologic conditions of a slope. While GIS is used to create a database, data management, data display and to analyze data such as thematic maps of land use/land cover, normalized difference vegetation index (NDVI), rainfall data and soil texture. This paper highlights the analysis of the condition of the Watershed Kuranji River experiencing flash floods, using remote sensing satellite image of Landsat ETM 7 in 2009 and 2012 and Geographic Information System (GIS). Furthermore, the data was analyzed to determine whether this flash flood occurred due to extreme rain or collapse of existing natural dams in the upstream of the Kuranji River.

Monitoring shoreline change using Remote sensing and GIS: A case study of padang coastal area, Indonesia

Padang city is a township at the outskirt of Arau River. Arau River often overflowed flooding the region city. To reduce this flood the Dutch government constructs the flood relief channel in 1926. The construction of this flood relief channel has resulted supply of sediment from Arau River to the coast become less which in turn caused the abrasion on the coast of Padang. In order to minimize the problem, the Department of Water Resources Management of West Sumatera has constructed several groins and jetties perpendicular to the shoreline. Thus, there is a vital need to conserve these constructed groins and jetties so that the shoreline equilibrium is protected. Here, monitoring changes in shoreline helps to identify the nature and processes that caused these changes. Over the past few years, Remote sensing (RS) and Geographic Information Systems (GIS) offer potential methods to solve many coastal erosion problems by providing a means for generating information, regular monitoring and analysis to predict and visualize future scenarios. The repetitive acquisition and synoptic capabilities of RS and GIS can be exploited to provide timely spatial data for coastal, enabling detection and monitoring of coastline movement. This paper therefore highlights the coastal monitoring processes and analyzing the shoreline change using RS and GIS techniques.

Early warning system for landslide hazard caused by earthquake and rainfall in West Sumatera Province, Indonesia

On Wednesday September 30, 2009, at 17:16 pm, a 7.6 Mw earthquake strucked the west coast of Sumatera, Indonesia. The earthquake caused severe landslide, death of 1,195 people and significant damage to approximately 140,000 houses and 4,000 other buildings. Out of the 1,195 people who died, 375 people had been buried in the landslide. The source of September 30, 2009 earthquake is in the intraplate not in the interplate (megathrusts). Interplate is the source of large earthquakes (>8.5) which occur repeatedly every 150 and 200 years. In recent times, large destructive earthquakes occurred in 2004, 2005, 2007 and 2010 along the Sumatra trough, for which the moment magnitudes were Mw 9.1, 8.6, 8.5, and 7.7, respectively. The magnitude of 2010 Mentawai earthquake was smaller than expected, hence, the strain has not been fully released. This means that there is still a high possibility of another gigantic earthquake occurring in the near future to this area. This paper presents the results of soil data in the laboratory using soil taken from the location of landslides and using the software SLOPE/W from Geoslope to obtain the amount of rainfall that caused the landslides. This is done to reduce the casualty of landslides due to the large earthquake that was followed by heavy rainfall. A simple early warning system based on rainfall threshold that causes landslides can be done by the community themselves.