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
Change of use legislation breaths new life into buildings
A run down on Class MA of the General Permitted Development Order.
Solar generation in the historic environment
Success requires understanding each site in detail.
Level 6 Design, Construction and Management BSc
CIOB launches first-ever degree programme to develop the next generation of construction leaders.
Open for business as of April, with its 2026 prospectus and new pipeline of housing schemes.
The operational value of workforce health
Keeping projects moving. Incorporating unplanned absence and the importance of health, in operations.
A carbon case for indigenous slate
UK slate can offer clear embodied carbon advantages.
Costs and insolvencies mount for SMEs, despite growth
Construction sector under insolvency and wage bill pressure in part linked to National Insurance, says report.
The place for vitrified clay pipes in modern infrastructure
Why vitrified clay pipes are reclaiming their role in built projects.
Research by construction PR consultancy LMC published.
Roles and responsibilities of domestic clients
ACA Safety in Construction guide for domestic clients.
Fire door compliance in UK commercial buildings
Architect and manufacturer gives their low down.
The new towns and strategic environmental assessments
12 locations of the New Towns Taskforce reduced to 7 within the new towns draft programme and open consultation.
Buildings that changed the future of architecture. Book review.