Drone Application for Generating a High Precision Orthophoto to Support Village Boundary and Land Use Mapping in Indonesia

Abstract

Many existing village maps in Indonesia are available without spatial references, including in Pandanrejo village in Kaligesing Sub-district, Purworejo District, Central Java. To date, the available village map of the Pandanrejo is sketches map which 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 and land use information of the Pandanrejo village. The drone captured the aerial images from an altitude of approximately 100 m and automatically take 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 drone images to the software to building orthomosaic as a basis for a digital orthophoto model. We then analyzed the errors of the resulted orthophoto map by comparing between the ratio of village boundary length to the total village area from drone mapping and terrestrial mapping using GNSS geodetic. The results showed that the drone mapping has successfully produced the village boundary map of the Pandanrejo village (i.e. a boundary length 7,473.2 m and an area 2.18 km²) that is comparable with the result of terrestrial area mapping corrected by GNSS geodetic. In addition, the drone has also successfully mapped the village land use with a total accuracy of 100% accurate. With these results, we suggest drone technology as an alternative method besides a traditional terrestrial method to create a definite village boundary and land use map to support the implementation of Indonesia Law No. 6 of 2014.