TY - JOUR

T1 - Cameras and settings for aerial surveys in the geosciences

T2 - Optimising image data

AU - O'Connor, James

AU - Smith, Mike J.

AU - James, Michael

N1 - The final, definitive version of this article has been published in the Journal, Progress in Physical Geography, 41 (3), 2017, © SAGE Publications Ltd, 2017 by SAGE Publications Ltd at the Progress in Physical Geography page: http://journals.sagepub.com/ppg on SAGE Journals Online: http://journals.sagepub.com/

PY - 2017/6

Y1 - 2017/6

N2 - Aerial image capture has become very common within the geosciences due to the increasing affordability of low-payload (<20 kg) unmanned aerial vehicles (UAVs) for consumer markets. Their application to surveying has subsequently led to many studies being undertaken using UAV imagery and derived products as primary data sources. However, image quality and the principles of image capture are seldom given rigorous discussion. In this contribution we firstly revisit the underpinning concepts behind image capture, from which the requirements for acquiring sharp, well-exposed and suitable image data are derived. Secondly, the platform, camera, lens and imaging settings relevant to image quality planning are discussed, with worked examples to guide users through the process of considering the factors required for capturing high-quality imagery for geoscience investigations. Given a target feature size and ground sample distance based on mission objectives, the flight height and velocity should be calculated to ensure motion blur is kept to a minimum. We recommend using a camera with as large a sensor as is permissible for the aerial platform being used (to maximise sensor sensitivity), effective focal lengths of 24–35 mm (to minimise errors due to lens distortion) and optimising ISO (to ensure the shutter speed is fast enough to minimise motion blur). Finally, we give recommendations for the reporting of results by researchers in order to help improve the confidence in, and reusability of, surveys through providing open access imagery where possible, presenting example images and excerpts and detailing appropriate metadata to rigorously describe the image capture process.

AB - Aerial image capture has become very common within the geosciences due to the increasing affordability of low-payload (<20 kg) unmanned aerial vehicles (UAVs) for consumer markets. Their application to surveying has subsequently led to many studies being undertaken using UAV imagery and derived products as primary data sources. However, image quality and the principles of image capture are seldom given rigorous discussion. In this contribution we firstly revisit the underpinning concepts behind image capture, from which the requirements for acquiring sharp, well-exposed and suitable image data are derived. Secondly, the platform, camera, lens and imaging settings relevant to image quality planning are discussed, with worked examples to guide users through the process of considering the factors required for capturing high-quality imagery for geoscience investigations. Given a target feature size and ground sample distance based on mission objectives, the flight height and velocity should be calculated to ensure motion blur is kept to a minimum. We recommend using a camera with as large a sensor as is permissible for the aerial platform being used (to maximise sensor sensitivity), effective focal lengths of 24–35 mm (to minimise errors due to lens distortion) and optimising ISO (to ensure the shutter speed is fast enough to minimise motion blur). Finally, we give recommendations for the reporting of results by researchers in order to help improve the confidence in, and reusability of, surveys through providing open access imagery where possible, presenting example images and excerpts and detailing appropriate metadata to rigorously describe the image capture process.

KW - Unmanned aerial vehicle

KW - digital image

KW - photography

KW - remote sensing

KW - aerial image

KW - STRUCTURE-FROM-MOTION

KW - CLOSE RANGE PHOTOGRAMMETRY

KW - UNMANNED AIRCRAFT SYSTEM

KW - DIGITAL PHOTOGRAMMETRY

KW - SOIL-EROSION

KW - TOPOGRAPHY

KW - PHOTOGRAPHY

KW - ACQUISITION

KW - CALIBRATION

U2 - 10.1177/0309133317703092

DO - 10.1177/0309133317703092

M3 - Journal article

VL - 41

SP - 325

EP - 344

JO - Progress in Physical Geography

JF - Progress in Physical Geography

SN - 0309-1333

IS - 3

ER -