Optimization of Ground Control Point Distribution for Unmanned Aerial Vehicle Photogrammetry for Inaccessible Fields

Abstract

Ground control point (GCP) is an important calibration factor when correcting position information during unmanned aerial vehicle (UAV) remote sensing. Studies of the optimal number and distribution shape of GCPs have been conducted worldwide in recent years. However, when conducting surveys at houses, construction sites, farming lands, forests, and some other locations, it is both difficult and destructive to install GCP inside the subject area. In many cases, it is only possible to install GCP at the outer edge around the area. Therefore, this study aims to suggest the optimal GCP distribution pattern, which can provide the highest accuracy, when only the outer edge of a particular area is available. In this research, 88 GCP patterns have been validated and compared at an 18 ha farm. Results show that the patterns with GCPs distributed evenly around the field provided the best calibration (RMSE = 0.15 m). If this kind of pattern is not achievable because of obstructions, patterns with GCPs distributed evenly around half of the field or forming an evenly distributed triangle can provide moderate accuracy (RMSE = 0.18 m and 0.43 m, respectively). Patterns with GCPs forming a straight line yielded the worst accuracy (RMSE = 2.10 m). This shows that GCP distributions of a two-dimensional shape, even if the surrounding area is small, are better calibrated than a long, straight line. These results strongly suggest that appropriate GCP distribution patterns in the study areas will provide satisfactory accuracy for constructing integrated monitoring systems of diverse resources.

Analisis Pengaruh Jumlah GCP (Ground Control Point) Terhadap Akurasi Peta Orthofoto Pada Jalan Yang Berkarakter Curam Dengan Tikungan Tajam Hasil Pemotretan Udara Metode Uav-Fotogrametri

“…Keunggulan metode UAV-Fotogrametri berupa resolusi Jurnal Qua Teknika Vol. 13 Jurnal Qua Teknika, (2023), 13(1): 61-74 62 pengamatannya yang tinggi serta efisiensi waktunya dibandingkan dengan satelit penginderaan jauh, menjadikannya platform yang paling banyak dieksplor dewasa ini [1]. Perkembangan pesat ini menjadikan UAV berkontribusi pada berbagai bidang seperti pembangunan model 3-dimensi untuk deteksi perubahan geomofologi [2], pendokumentasian situs budaya [3], deteksi gangguan jalan [4], estimasi volume timbunan [5] dan sebagainya.…”

“…Geolokasi GCP sendiri termasuk di dalamnya adalah detail error pada posisi X dan Y serta Z baik itu pada GCP maupun ICP. Perhitungan error pada posisi horizontal mengacu pada persamaan (1) sedangkan error pada posisi vertical sama dengan error Z [1].…”

Analysis of UAV Flight Patterns for Road Accident Site Investigation

“…The widespread application of such a method would enable police officers to speed up the on-site crash investigation procedure and open the affected road section for traffic sooner. As time is of primary concern, the methods developed here do not apply Ground Control Points (GCPs), which are frequently utilized to increase accuracy [32,33]. Also, for the sake of simplicity, the default camera settings are applied, as opposed to [34].…”