Noorhadi Rahardjo, Djarot Heru Santoso, Hero Marhaento
Faculty of Geography, Universitas Gadjah Mada, Yogyakarta, Indonesia,
*Corresponding Author: noorhadi@ugm.ac.id
Abstract. Many existing village maps in Indonesia are available without spatial references, includes in Pandanrejo village in Kaligesing Sub-district, Purworejo District, Central Java. To date, the village map of the Pandanrejo still uses sketches in its making and potentially overlaps with the area of adjacent villages. In this study, we used a commercial drone DJI Phantom 4 for generating a high precision orthophoto to create the exact boundaries of the Pandanrejo village. The drone captured the aerial images from an altitude of approximately 100 m and automatically toke an image every 3 seconds giving an overlap of each image around 70% of each pair of neighboring images. By this mission plan, the drone collected of about 1,312 aerial photographs. In order to obtain better geo-referencing results, eleven Ground Control Points (GCPs) distributed over the study area were obtained by GNSS geodetic tools. Furthermore, the Structure from Motion (SfM) algorithm was used to generate point clouds, digital surface models, and digital orthophoto model. These processes were carried out by using Agisoft PhotoScan software completing 10 steps in the workflow starting from adding images to the software to build orthomosaic as a basis for a digital orthophoto model. We then analysed the accuracy of the resulted orthophoto map by assessing three accuracy parameters namely the accuracy of points, lines, and areas. The results showed that the drone has successfully produced the topographic map of the Pandanrejo village with a point accuracy of about 20.3 meters, line accuracy of about 13.3 meters, and area accuracy of about 0.5%. Besides the topographic map, the drone has also successfully mapped the village land cover with a total accuracy close to 100% accurate. With these results, we suggest drone technology as an alternative method besides a traditional terrestrial method to create a definite village boundary to support the implementation of Indonesia Law No. 6 of 2014 to determine the village area authority.
Keyword: Boundary Mapping, Drone, Photogrammetric, Orthophoto, Pandanrejo Village
