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
A threat to the creativity that makes London special.
How can digital twins boost profitability within construction?
A brief description of a smart construction dashboard, collecting as-built data, as a s site changes forming an accurate digital twin.
Unlocking surplus public defence land and more to speed up the delivery of housing.
The Planning and Infrastructure bill oulined
With reactions from IHBC and others on its potential impacts.
Farnborough College Unveils its Half-house for Sustainable Construction Training.
Spring Statement 2025 with reactions from industry
Confirming previously announced funding, and welfare changes amid adjusted growth forecast.
Scottish Government responds to Grenfell report
As fund for unsafe cladding assessments is launched.
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Architects Academy at an insulation manufacturing facility
Programme of technical engagement for aspiring designers.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.