Remote Sensing of Human Settlements

Human settlements refer to locations where people live, work, and develop infrastructure, commonly classified as rural, urban, or suburban environments. Institutions monitoring human settlements aim to capture both the physical footprint of settlements and, where possible, associated population distribution and human activity patterns. Space-based observations can measure their physical footprint, including buildings, transport infrastructure, impervious surfaces, artificial lighting, and related land-use change. 1) 2)

Human settlement monitoring has become increasingly important due to unprecedented population increase and rapid urbanisation causing a growth in the size of human settlements, both in terms of the footprint they occupy and the population they contain. More than half of the global population now lives in urban areas, placing increasing demands on infrastructure, housing, transport systems, and natural resources. Satellite observations provide a globally consistent means of characterising how human populations occupy and transform the Earth’s surface over time, with repeated, objective, and comparable measurements over time and across regions. This allows urban planners and policymakers to assess urban expansion, informal settlement growth, land consumption, exposure to hazards, and infrastructure development. 3)

Satellite Monitoring Techniques

Satellite data can enable the detection of human settlements using multiple observation principles supported by complementary sensor types. Translating Earth observation data into meaningful settlement boundaries requires analytical approaches that group remotely sensed built-up surfaces and surrounding open spaces in ways that reflect the spatial organisation of cities and metropolitan regions.

Optical multispectral instruments can measure reflected sunlight across visible and infrared wavelengths, allowing built-up areas to be distinguished from vegetation, soil, and water based on differences in how surface materials absorb and reflect radiation. High-resolution optical imagery enables detailed mapping of individual buildings, transport networks, and urban structure, while medium-resolution observations provide consistent and repeatable measurements of settlement extent at regional to global scales.

Nighttime lights (NTL) refer to artificial illumination emitted after dark from sources such as cities, transport networks, industrial facilities, gas flares, and fishing fleets. Space-based NTL data are widely used in the remote sensing of human settlements as a proxy for human presence and activity intensity, as brighter and more persistent illumination generally corresponds to higher levels of infrastructure development, electrification, and economic activity. Long-term global NTL observations have been provided by multispectral radiometers such as the Operational Linescan System (OLS) which operated from the 1990s to the 2010s, followed by the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB), which delivers daily global low-light imaging in the visible and near-infrared wavelengths. VIIRS is carried onboard NASA’s Suomi National Polar-orbiting Partnership (NPP) satellite and NOAA’s Joint Polar Satellite System (JPSS) satellites. NASA’s Black Marble product suite uses VIIRS DNB observations to provide corrected global NTL products at daily, monthly, and annual temporal resolutions, supporting the analysis of human activity, energy infrastructure, disaster impacts, light pollution, gas flaring, and fishing activity. 4) 5) 14)

Synthetic Aperture Radar (SAR) instruments observe the Earth by actively transmitting microwave signals and measuring returned backscatter, supplementing passive measurements. Built structures often produce strong radar returns through double-bounce and corner reflector effects, making built-up areas stand out against vegetation and bare soil. Radar observations are particularly valuable in tropical and high-latitude regions where persistent clouds limit optical imaging, and can support observations where NTL signals are weak. Lidar (Light Detection and Ranging) uses reflected laser light to determine distances and generate high-resolution three-dimensional geospatial maps, enabling airborne and satellite-based instruments to provide complementary measurements of building height and urban vertical structure. 6)

Sustainable Development Goals (SDGs)

The 2030 Agenda for Sustainable Development is a global call for coordinated action to address social, economic, and environmental challenges through 17 Sustainable Development Goals (SDGs). Earth observation monitoring of human settlements supports several of these goals, most directly SDG 11 (Sustainable Cities and Communities), by enabling measurement of urban expansion, land-use efficiency, infrastructure access, and population exposure to environmental risks. Settlement datasets also contribute to SDG 1 (No Poverty), SDG 7 (Affordable and Clean Energy) through electrification assessment using nighttime lights, SDG 9 (Industry, Innovation and Infrastructure), SDG 13 (Climate Action) via land-use and emissions analysis, and SDG 15 (Life on Land) by monitoring urban encroachment into natural ecosystems. 1) 2) 7)

EO monitoring allows global inventories of built-up areas, urban growth trajectories, settlement density estimation, infrastructure distribution, population modelling inputs, disaster exposure assessment, and long-term urbanisation trends. Multi-temporal satellite archives allow consistent comparison between historical and present settlement patterns, supporting evidence-based urban planning and sustainable development policy. 15)

Example Products

Copernicus Global Human Settlement Layer (GHSL)

The Copernicus Global Human Settlement Layer (GHSL) is derived primarily from multi-temporal imagery acquired across the Landsat series, including by the Multispectral Scanner (MSS) onboard Landsat 1, 2 and 3; the Thematic Mapper (TM) onboard Landsat 4 and 5; the Enhanced Thematic Mapper Plus (ETM+) onboard Landsat 7; and the Operational Land Imager (OLI) onboard Landsat 8. GHSL also incorporates data from Sentinel-2 optical composites, complemented by Sentinel-1 SAR observations and other ancillary datasets. Built-up areas are detected through automated global image mining and supervised classification of multi-temporal satellite data using spectral, textural, and morphological features, while population grids are produced by disaggregating census data according to mapped built-up extent. The dataset provides harmonised global settlement layers for multiple epochs, including 1975, 1990, 2000, and 2014, with more recent Sentinel-based updates released periodically rather than on a fixed annual cycle. GHSL supports global monitoring of urbanisation, population exposure, and settlement dynamics, contributing to SDG reporting, disaster risk assessment, climate analysis, and long-term studies of human–environment interactions. 8) 9) 10)

World Settlement Footprint (WSF) Evolution

The World Settlement Footprint (WSF) Evolution is a global 30 m settlement dataset that records per-pixel estimations of the year of first settlement between 1985 and 2015. Rather than providing population estimates or built-up fractions, the product maps the historical expansion of settlements over a 30-year period. 11) 12)

WSF Evolution is derived from multi-temporal Landsat 5 and Landsat 7 imagery. Annual image stacks and spectral indices, including the Normalised Difference Built-up Index (NDBI), Normalised Difference Vegetation Index (NDVI), and Modified Normalised Difference Water Index (MNDWI), are used with a Random Forest classifier to distinguish settled from non-settled areas.

VIIRS Nighttime Lights (NTL) composites

VIIRS NTL composites are derived from the Day/Night Band of the VIIRS instrument onboard the Suomi NPP and Joint Polar Satellite System (NOAA-20 and NOAA-21) polar-orbiting satellites, which measure low-light visible and near-infrared radiance emitted from the Earth’s surface at night. The products are generated by combining multiple nighttime observations after screening for effects such as clouds, moonlight, lightning, and stray light, producing monthly and annual average radiance grids of nighttime illumination. The global dataset extends from 2012 to the present, with routinely updated monthly composites and annual stable-light products supporting long-term analysis. VIIRS NTL data enable monitoring of urbanisation, electrification, economic activity, and disaster impacts through changes in the spatial distribution and intensity of nighttime lighting. 4) 5) 13)

Related Missions

A wide range of Earth observation missions contribute to settlement monitoring by providing mid-range optical, radar, thermal, and nighttime illumination measurements. Together, these missions enable detection of physical infrastructure, monitoring of urban dynamics, and long-term analysis of human activity patterns at regional to global scales.

Sentinel 1

Part of the Copernicus Programme, Sentinel-1 is a constellation of C-band Synthetic Aperture Radar imaging satellites operated by ESA, carrying the C-SAR instrument to provide all-weather, day-and-night observations of the Earth’s surface. The series launched with Sentinel-1A in April 2014, and is continued by Sentinel-1C and -1D. Sentinel-1 radar data play a key role in global settlement mapping, contributing to datasets such as the GHSL and the WSF.

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Sentinel 2

Sentinel-2 is a constellation of optical imaging satellites also within the Copernicus Programme, first launched in 2015. Each satellite carries the Multispectral Instrument (MSI), providing high-resolution observations across visible and infrared wavelengths for land surface monitoring. Sentinel-2 optical composites contribute to global settlement mapping products, including the GHSL.

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Landsat

The Landsat programme, jointly operated by NASA and the U.S. Geological Survey (USGS), provides the longest continuous satellite record of the Earth’s land surface since 1972. Multispectral observations acquired by instruments such as the Operational Land Imager (OLI) on board Landsat-8 enable consistent detection of built-up surfaces and land-cover change over decades, forming a foundational data source for global settlement mapping products including the GHSL and WSF Evolution.

Landsat-7, Landsat-8, Landsat-9

VIIRS

The Visible Infrared Imaging Radiometer Suite (VIIRS) is a multispectral radiometer carried onboard NASA’s Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, launched in 2011, and the NOAA Joint Polar Satellite System (JPSS) missions. VIIRS provides daily global observations of the Earth’s surface and atmosphere across visible and infrared wavelengths. Its Day/Night Band (DNB) enables the detection of low-light emissions at night and provides the primary data source for global nighttime lights products used to monitor human settlements and patterns of human activity.

Suomi NPP, JPSS

References  

1) United Nations, “Human Settlements,” URL: https://www.un.org/en/global-issues/human-settlements

2) United Nations, “Sustainable Development Goals,” URL: https://sdgs.un.org/goals

3) European Commission Joint Research Centre, “Why Study Human Settlements Using Earth Observation?,” Atlas of the Human Planet 2016, URL: https://human-settlement.emergency.copernicus.eu/documents/atlas2016_section2_1.pdf?t=1476110579

4) NASA Earthdata, “Nighttime Lights,” 20 November 2025, URL: https://www.earthdata.nasa.gov/topics/human-dimensions/nighttime-lights

5) Earth Observation Group (Colorado School of Mines), “VIIRS Nighttime Light Data Products,” URL: https://eogdata.mines.edu/products/vnl/

6) NASA Earthdata, “Synthetic Aperture Radar (SAR),” URL: https://www.earthdata.nasa.gov/learn/earth-observation-data-basics/sar

7) United Nations, “Transforming our World: The 2030 Agenda for Sustainable Development,” 2015, URL: https://sdgs.un.org/2030agenda

8) European Commission Joint Research Centre, “The Global Human Settlement Layer (GHSL): Concepts, Methods and Applications,” URL: https://human-settlement.emergency.copernicus.eu/documents/GHSL_Concepts_methods_and_applications.pdf?t=1646660336

9) European Commission Joint Research Centre, “Global Human Settlement Layer Data Collection,” URL: https://data.jrc.ec.europa.eu/collection/GHSL

10) Copernicus Emergency Management Service, “Global Human Settlement Layer,” URL: https://human-settlement.emergency.copernicus.eu/

11) German Aerospace Center (DLR), “World Settlement Footprint (WSF) Evolution,” URL: https://geoservice.dlr.de/web/maps/eoc:wsfevolution

12) EO Portal, “WSF (World Settlement Footprint) Evolution from Space,” URL:https://www.eoportal.org/ftp/satellite-missions/w/WSF_151121/WSF.html

13) Payne Institute for Public Policy – Earth Observation Group, “Nighttime Lights,” URL: https://payneinstitute.mines.edu/eog/nighttime-lights/

14) NASA Earthdata, “Black Marble,” URL: https://www.earthdata.nasa.gov/data/projects/black-marble 

15) Committee on Earth Observation Satellites (CEOS), “EO Support Sheet: SDG Indicator 11.3.1 – Ratio of Land Consumption Rate to Population Growth Rate,” December 2024, URL: https://ceos.org/document_management/Ad_Hoc_Teams/SDG-AHT/Support%20Sheets/SDG_11.3.1_EO_Support_Sheet_v2024_1.pdf