XXII ISPRS Congress 2012: Technical Commission VII

Bibliographic data

Multivolume work

Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Type of content:: Konferenzschrift

Year of publication:: 2013

Place of publication:: Red Hook, NY

Identifier (digital):: 1663813779

Reihe:: ISPRS archives

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Publisher of the original:: Curran Associates, Inc.

Document type:: Multivolume work

Volume

Persistent identifier:: 1663821976

Title:: Technical Commission VII

Scope:: 546 Seiten

Type of content:: Konferenzschrift

DOI:: 10.14463/KXP:1663821976

Year of publication:: 2013

Place of publication:: Red Hook, NY

Identifier (digital):: 1663821976

Illustration:: Illustrationen, Diagramme

Reihe:: ISPRS archives (volume 39, B7 (2012))

Signature of the source:: ZS 312(39,B7)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

Publisher of the original:: Curran Associates, Inc.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [VII/7, III/2, V/1, V/3, ICWG V/I: LOW-COST UAVS (UVSS) AND MOBILE MAPPING SYSTEMS]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: AERIAL TERRAIN MAPPING USING UNMANNED AERIAL VEHICLE APPROACH K. N. Tahar

Document type:: Multivolume work

Structure type:: Chapter

International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia (Figure 1). These gadgets increase the precision of image acquisition conducted by UAV duri i i Figure 1. An example of fixed-wing UAV The photogrammetric products such as digital elevation model and digital orthophoto can be produced after a certain orientations through photogrammetric processes (Tahar and Ahmad, 2011; Tahar and Ahmad, 2012). The protogrammetric processes involve interior orientation, exterior orientation, aerial triangulation and bundle adjustment. Interior orientation requires information of camera calibration parameters such as focal length, principal distance (X,, Y,), radial lens distortion (K,, K,, Kj), tangential lens distortion (P,, P,) and affinity (B,) and scale factor (By). Exterior orientation requires coordinates on the ground to define the image position was same during flight mission. Exterior orientation can be processed by using ground control points which are established by total station or global positioning system. In addition, inertial measurement unit is used to improve onboard GPS coordinates during flight mission. Inertial measurement unit (Mikropilot) was link with navigation control board and records all UAV position, altitude and rotates coordinates during flight mission. These parameters were saved automatically in GPS log file and were used during post processing during exterior orientation. This study introduce a new method for image registration in the image processing phase. 1.2 Study Area This study was conducted in Gelang Patah in Johor, Malaysia, which is located within latitudes 1° 26’N - 1° 27°N and longitudes 103° 34’E — 103° 35'E. The map of the study area is shown in Figure 2. The landuse at the study area mainly includes urban area, forest, plantation oil palm and bare land. Figure 2. Study area 2. DATA ACQUISITION 2.1 Flight Preparations Data acquisition is solely obtained from unmanned aerial vehicle, with a specific fixed wing unit which autopilot system has been adopt from Mikropilot product. This UAV is equipped 494 with the current and advanced technologies such as onboard GPS, fiber optics gyro, autopilot chipset, electronic speed controller, wireless antenna, camera mount, high resolution digital camera, high end transmitter and inertial navigation system (Mikropilot). Figure 3 shows the digital camera that was installed at the bottom of UAV. The images were taken autonomously by UAV based on flight path which was programmed in a flight mission control software. Pre-flight planning is a must in photogrammetric work because it will reflect the quality of the end products. The coordinates were obtained from Google Earth Pro to identify the area of interest. Figure 3. Digital camera Generally, Google Earth inherited 20-50 meter accuracy (Potere, 2008) but it is still the fastest and the easiest way to get an idea of the study area, other alternative is to visit the study area and conduct survey observation. Next, the images of study area were cropped and saved in jpeg file. Raster image (jpeg file) needs to be registered by using ground control points to perform georeference processing. These processes can be done with well known geographical information system (GIS) software such as ArcGIS, ArcView or MapInfo software. There are at least three control points needed to perform georeference processed which can be obtained from google earth or GPS observation. Then, georeferenced images will be opened in lentsika flight planning software. Lentsika software is very effective for UAV flight planning because it includes coverage area, required resolution, number of images, attitudes, altitudes and flight path. After the user is satisfied with the flight planning of the study area, then it is saved in *.fly file. In the software, user needs to specify the area of interest and to determine each corner of the study. This software can generate flight path automatically based on user's input. Finally, flight planning file from lentsika will be opened in ground control software known as Horizon software. Horizon software will finalize the flight pattern and altitude control. Normally, user is requested to enter ground resolution required for the mission. The software will automatically calculate the number of images taken, the number of waypoint, flight path and it will also calculate the exposure time. Flight planning file will be uploaded into autopilot chip or autonomous flight system in UAV via cable or wirelessly. In this study, we used 7 centimeter ground resolution at an altitude of 320 meter or 1200 feet. The operator will monitor on the availability of GPS onboard and will ensure that the wireless connection is working. The operator will also monitor on the speed of propeller, UAV wings, camera setting, and other function such as yaw and pitch sensor. In many cases, fixed wing UAV needs a runway to launch at the starting site. However, we use to throw the UAV to add some energy for the launch. The UAV will be radio controlled by operator until it reaches the first point of the planned flight route. After the UAV reaches the first point, it is operated autonomously by the flight mission control software. This kind of UAV also does not need a runway to land but it needs a net to hold the UAV during the landing steps.

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