GPS precise point positioning for UAV photogrammetry

Ben Grayson,Jon P Mills,Darion S Grant,Nigel T Penna

doi:10.1111/phor.12259

Abstract

AbstractThe use of Global Positioning System (GPS) precise point positioning (PPP) on a fixed‐wing unmanned aerial vehicle (UAV) is demonstrated for photogrammetric mapping at accuracies of centimetres in planimetry and about a decimetre in height, from flights of 25 to 30 minutes in duration. The GPS PPP estimated camera station positions are used to constrain estimates of image positions in the photogrammetric bundle block adjustment, as with relative GPS positioning. GPS PPP alleviates all spatial operating constraints associated with the installation and the use of ground control points, a local ground GPS reference station or the need to operate within the bounds of a permanent GPS reference station network. This simplifies operational logistics and enables large‐scale photogrammetric mapping from UAVs in even the most remote and challenging geographic locations.

Highlights

UNMANNED AERIAL VEHICLES (UAVs) have recently become a popular platform for photogrammetric data acquisition because of their flexible nature and low cost in comparison to manned aerial platforms (Colomina and Molina, 2014)
This paper investigates whether direct georeferencing of a lightweight, fixed-wing UAV platform for use in large-scale mapping is possible by using kinematic Global Positioning System (GPS) precise point positioning (PPP)
An assessment of GPS PPP-based direct georeferencing on a fixed-wing UAV for large-scale photogrammetric mapping has been presented. Such a workflow alleviates all spatial operating constraints associated with the installation and the use of a local GPS reference station, ground control points (GCPs) or the need to operate within the bounds of a permanent GPS reference station network

Summary

Introduction

UNMANNED AERIAL VEHICLES (UAVs) have recently become a popular platform for photogrammetric data acquisition because of their flexible nature and low cost in comparison to manned aerial platforms (Colomina and Molina, 2014). Regarding the PPK-BBA solutions, check point RMSEs are better than 1 pixel in all coordinates for Flights 1 and 2 (equivalent to less than 3 cm on the ground) These results reflect the high accuracy and precision of the GPS PPK camera positions, and are similar to the check point errors obtained in comparable studies (Rehak and Skaloud, 2015; Gerke and Przybilla, 2016; Benassi et al, 2017; St€ocker et al, 2017). They suggest that the principal distance (focal length) has been estimated with pixel-level (equivalent) accuracy for both flights. As the one-GCP configurations show variable improvements, for optimal reliability it is suggested that four GCPs be used if possible, as with traditional GPSsupported aerial triangulation (for instance, Ackermann and Schade, 1993; Yuan, 2009)

Findings

Applications and Discussion

Conclusions and Outlook