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 forward thinking, inclusive global community of members.
From engineered product life-spans, to their extension.
Circular economy in the built environment
A brief description from 2021. Where are we now?
Mental Health Awareness Week with ABS
Architects Benevolent Society programme of activity.
CLC publishes domestic retrofit competency framework
Roadmap of Skills for net zero.
May 13-19: Moving more for our mental health.
Understanding is key to conservation.
Open industry engagement survey seeks responses
Institutions and the importance of engagement.
National Retrofit Hub unveils new guide
Digital Building Logbooks and Retrofit: An Introduction.
Enhancing construction site reporting efficiency
Through digitisation and the digital revolution.
Noise in the built environment
BSRIA guide TG 20/2021.
17,000 people suffer conditions as a result of exposure to excessive noise at work.
Turning down the noise: Auditory health
A pervasive risk with far-reaching consequences.
Getting the most out of heat pumps and heating
How heat pumps work and how they work best.
Cost-of-living crisis and home improvement plans
Starting on the right footing and top tips for projects.
Electrotechnical excellence, now open for entries.