Research by Dr. Nikhil Kaza
According to UN-Habitat, about a third of the population in the world live in irregular/informal settlements/favelas/shanty towns/slums. Whatever names these neighbourhoods take around the world, these settlements are at the core of many urban regions around the world; they provide affordable housing for urban poor but at high social and health costs. However, to study these phenomena, we need to know where these settlements are and how they change over time.
Nikhil Kaza is taking on this challenge of identifying and characterising these irregular settlements in Bengaluru, India, a rapidly urbanising city. This city has become a technology hub that spurs large economic development and population growth (~40% between 1991-2011) at great environmental and human cost. As of 2017, 10 million people are estimated to live in this city, and the Karnataka Slum Development Board estimates that there are 600 slums in the city. However, other non-governmental sources contend that this is a gross underestimate and puts this number much higher (~1500). According to unofficial estimates, a quarter to a third of the population of Bengaluru live in these slums.
Nikhil is working identifying these settlements using high-resolution satellite imagery. Using and blending multiple techniques such as human image interpretation, machine learning ensembles, crowdsourcing validation and field verification, he is able to identify over 2500 non-trivial candidate neighbourhoods in different categories, putting the number much closer to estimates of the non-governmental sources. Using high-resolution images (2m – 0.5m) from Digital Globe Foundation, and blending volunteered information from OpenStreetMap as well as official and publicly available sources, his team is able to construct a picture of built environment of the city of Bengaluru. One of the key challenge is to manage and process 8 billion data points, to arrive at these conclusions.
Computers, while great at processing large data have not yet figured out how to quickly categorise complex information.To weed out false positives identified by the machine learning algorithms, the team created a website (sensingsettlements.org) where citizen scientists to help validate if the images presented to them are irregular or not. By generating large number of responses from a lot of users with different levels of experience, expertise and accuracy, Nikhil and his team hopes to both improve the accuracy of the machine learning algorithms and provide more current datasets for government and non-governmental agencies to target their policies and programs.
Not all irregular settlements are informal; the extent to which these settlements are outside the formal sector can only be determined through field validation and surveys and examination of public records. Currently field teams are deployed in these neighbourhoods to conduct a detailed household level survey to understand how the settlements works and neighbourhoods operate.
The plan is to scale up this work to cover all of India and perhaps all of the world. With the explosion of availability of high-resolution geospatial data, it is becoming possible to study these areas in greater detail.