Determining the Optimal Number of Ground Control Points for Varying Study Sites through Accuracy Evaluation of Unmanned Aerial System-Based 3D Point Clouds and Digital Surface Models

Jae Jin Yu,Eun Jung Lee,Dong Woo Kim,Seung Woo Son

doi:10.3390/drones4030049

Abstract

The rapid development of drone technologies, such as unmanned aerial systems (UASs) and unmanned aerial vehicles (UAVs), has led to the widespread application of three-dimensional (3D) point clouds and digital surface models (DSMs). Due to the number of UAS technology applications across many fields, studies on the verification of the accuracy of image processing results have increased. In previous studies, the optimal number of ground control points (GCPs) was determined for a specific area of a study site by increasing or decreasing the amount of GCPs. However, these studies were mainly conducted in a single study site, and the results were not compared with those from various study sites. In this study, to determine the optimal number of GCPs for modeling multiple areas, the accuracy of 3D point clouds and DSMs were analyzed in three study sites with different areas according to the number of GCPs. The results showed that the optimal number of GCPs was 12 for small and medium sites (7 and 39 ha) and 18 for the large sites (342 ha) based on the overall accuracy. If these results are used for UAV image processing in the future, accurate modeling will be possible with minimal effort in GCPs.

Highlights

Various studies have been conducted to investigate the utility of unmanned aerial systems (UASs) and unmanned aerial vehicles (UAVs) as the technologies have developed and popularized.These studies mainly acquire data through UAVs equipped with optical (RGB), multi-spectral, or infrared sensors [1,2,3], and produce 3D point clouds and digital surface models (DSMs) using image processing programs
ground control points (GCPs) for modeling multiple areas, the accuracy of 3D point clouds and DSMs were analyzed in three study sites with different areas according to the number of GCPs
The accuracy of 3D point clouds and DSMs were analyzed in three study sites with different areas according to the number of GCPs to determine the optimal number of GCPs, which is required when 3D modeling is performed for target sites with different areas using UAVs

Summary

Introduction

Various studies have been conducted to investigate the utility of unmanned aerial systems (UASs) and unmanned aerial vehicles (UAVs) as the technologies have developed and popularized. These studies mainly acquire data through UAVs equipped with optical (RGB), multi-spectral, or infrared sensors [1,2,3], and produce 3D point clouds and digital surface models (DSMs) using image processing programs. Before the popularization of UAV technology, satellites, manned aircrafts, and professional surveillance cameras were the prominent methods of data acquisition for research [4,5]. DSM is a 2.5D raster format data generated with stereo images [5,11]

Objectives

Methods

Results

Discussion

Conclusion