Understanding urban spaces using satellite imagery

Satellite imagery has become a valuable data source for understanding the change in Earth's physical environment. As it is not limited to geographical units or boundaries, it can be used to provide consistent coverage of the Earth's surface. Remotely sensed imagery can be used in a number of ways, such as monitoring and detecting the changes in urban areas; being able to map and visualise urban areas at different scales is important in discerning how urban expansion is changing and affecting its surroundings. This can provide an alternate source of information not only for the physical environment but also socio-economic factors. In recent years, there has been increasing use of night-time lights data to understand and quantify economic activity in urban centres. During the Covid- 19 pandemic, many studies in India and China made use of night-time lights as an approximation for real-time human activity and economic activity.

The Gauteng City-Region encompasses a large proportion of South Africa's economic activity, and according to StatsSA's 2020 mid-year population estimates, approximately 26% of South Africa's population is located within Gauteng. Satellite imagery can provide a better understanding of this complex urban space by supplementing existing datasets (such as census data) with more current information and broadening the range of scales that can be applied to the GCR. It also presents the opportunity to visualise Gauteng through the various forms that satellite imagery presents itself.

This project aims to use satellite imagery to investigate the spatial spread of economic activity across Gauteng's urban centres.

Outputs

Naidoo, Y., Maree, G., Naidoo, L. "Estimating change in the spatial economy of the city of Johannesburg using nighttime lights imagery and population data in a Random Forest modelling environment", Proc. SPIE 12735, Remote Sensing Technologies and Applications in Urban Environments VIII, 1273504 (19 October 2023); https://doi.org/10.1117/12.2684320

Naidoo, Y. and Maree, G (2020) ‘Gauteng going dark: How nighttime light intensity changed during early stages of lockdown', Map of the Month, Gauteng City-Region Observatory, July 2020.

Maree, G. and Naidoo, Y (2019) ‘Gauteng at night: light intensity at 2am’, Map of the Month, Gauteng City-Region Observatory, September 2019.

Presentations

Yashena Naidoo, Gillian Maree, Laven Naidoo (September 2023) - 'Estimating change in the spatial economy of the City of Johannesburg using nighttime lights imagery', SPIE Sensors + Imaging - Remote Sensing Technologies and Applications in Urban Environments VIII, RAI Amsterdam, 3 September 2023

Yashena Naidoo, Gillian Maree, Laven Naidoo (May 2023). ‘Estimating 10 years of spatial economic change in Johannesburg (2011-2021)’, Faces of the City Seminar, 2 May 2023.

Yashena Naidoo, Gillian Maree, Laven Naidoo (April 2023). 'Estimating 10 years of spatial economic change in Johannesburg (2011- 2021)'. City of Johannesburg International Relations Roundtable

Last updated: 11 December 2023.