Impact of UAV Surveying Parameters on Mixed Urban Landuse Surface Modelling

Muhammad Hamid Chaudhry,Anuar Ahmad,Qudsia Gulzar

doi:10.3390/ijgi9110656

Abstract

Unmanned Aerial Vehicles (UAVs) as a surveying tool are mainly characterized by a large amount of data and high computational cost. This research investigates the use of a small amount of data with less computational cost for more accurate three-dimensional (3D) photogrammetric products by manipulating UAV surveying parameters such as flight lines pattern and image overlap percentages. Sixteen photogrammetric projects with perpendicular flight plans and a variation of 55% to 85% side and forward overlap were processed in Pix4DMapper. For UAV data georeferencing and accuracy assessment, 10 Ground Control Points (GCPs) and 18 Check Points (CPs) were used. Comparative analysis was done by incorporating the median of tie points, the number of 3D point cloud, horizontal/vertical Root Mean Square Error (RMSE), and large-scale topographic variations. The results show that an increased forward overlap also increases the median of the tie points, and an increase in both side and forward overlap results in the increased number of point clouds. The horizontal accuracy of 16 projects varies from ±0.13m to ±0.17m whereas the vertical accuracy varies from ± 0.09 m to ± 0.32 m. However, the lowest vertical RMSE value was not for highest overlap percentage. The tradeoff among UAV surveying parameters can result in high accuracy products with less computational cost.

Highlights

Mapping and surveying always complement each other
The quality of Unmanned Aerial Vehicles (UAVs) Digital Surface Model (DSM) is dependent on a number of factors, such as sensor quality, platform properties, flight parameters, and image processing techniques
Flight parameters like flight height, flying speed, flight time, flying path, and image percentage overlap are a tradeoff between DSM quality and photogrammetric project computational cost

Summary

Introduction

Advancements in surveying techniques and technologies results in the accuracy enhancement of mapping products. The digital era has revolutionized surveying technologies and techniques. Developments in surveying technologies such as satellite remote sensing, aerial surveying, Light Detection and Ranging (LIDAR), and so on, complemented with image processing techniques and software developments have revolutionized 3D mapping (terrain modelling) of the Earth’s surface. The 3D mapping of the Earth’s surface is commonly known as a Digital Surface Model (DSM). Commencing from the early 1300s with ‘Jacob Staff’ and ‘Compass’ until today, the generation of elevation models have evolved from hand drawn or field drawn (With Plane Table Alidade in late 1800s) topo and planimetric maps, to digital representations as DSMs [1]. Recent developments in photogrammetry allow high-resolution photo-realistic terrain models to be constructed, producing unprecedented visualizations of the Earth’s surface [4]

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