Ground sample distance GSD
In digital photos taken from the air, a ground sample distance (GSD) - or ground sampling distance - is a calculation used to explain how the real world scale established by ground control points (GCPs) translates onto a map. They can also be referred to as ground projected sample interval (GSI) or ground projected instantaneous field of view (GIFOV).
Aerial surveys incorporate GSDs as a factor for generating accurate maps and models. It can be a useful calculation in several sectors, including construction, cartography, mining and so on.
GSDs can be incorporated into photogrammetry and aerial photography which can be used to create three dimensional topographic maps.The GSD describes the distance between the centre point of two consecutive pixels on a digital image. Without an accurate GSD, it can be difficult for surveyors to convert collected data into a usable map.
GSD calculations that are inaccurate by very small increments - even as little as a few centimetres - may have serious consequences. If a small mistake is extrapolated over a large number of pixels, it can result in significant discrepancies between the map and reality. To prevent this, use the smallest practical value to calculate GSD. An accurately selected GSD will allow the mapping device to generate detailed images while flying high enough to minimise the number of required photos.
Applied digital documentation In the historic environment, published on 19 March 2018 by Historic Scotland, defines ground sample distance (GSD) as: ‘The known real-world scale of an image pixel.’
Earth observation and aerial surveys, RICS professional standard, 6th edition, September 2021, published on 4 January 2022 by the Royal Institution of Chartered Surveyors (RICS), defines ground-sampled distance (GSD) as: ‘The distance between the centres of two consecutive pixels on the ground. GSD is a common way to define and refer to the spatial resolution of Earth observation and aerial imagery.’
[edit] Related articles on Designing Buildings
Featured articles and news
Electrical contractors welcome crackdown on late payment and push for clean energy.
Cyber Security in the Built Environment
Protecting projects, data, and digital assets: A CIOB Academy TIS.
Managing competence in the built environment
ITFG publishes new industry guide on how to meet the ICC principles.
The UK's campaign to reduce noise pollution: Mythbusting, articles and topic guides.
Setting Expectations on Competence Management
Industry Competence Committee.
New Scottish and Welsh governments
CIOB stresses importance of construction after new parliament elections.
The sad story of Derby Hippodrome
An historic building left to decay.
ECA, JIB and JTL back Fabian Society call to invest in skills for a stronger built environment workforce.
Women's Contributions to the Built Environment.
Calls for the delayed Circular Economy Strategy
Over 50 leading businesses, trade associations and professional bodies, including CIAT, and UKGBC sign open letter.
The future workforce: culture change and skill
Under the spotlight at UK Construction Week London.
A landmark moment for postmodern heritage.
A safe energy transition – ECA launches a new Charter
Practical policy actions to speed up low carbon adoption while maintaining installation safety and competency.
Frank Duffy: Researcher and Practitioner
Reflections on achievements and relevance to the wider research and practice communities.
The 2026 Compliance Landscape: Fire doors
Why 'Business as Usual' is a Liability.
Cutting construction carbon footprint by caring for soil
Is construction neglecting one of the planet’s most powerful carbon stores and one of our greatest natural climate allies.