364 research outputs found
The role of earth observation in an integrated deprived area mapping “system” for low-to-middle income countries
Urbanization in the global South has been accompanied by the proliferation of vast informal and marginalized urban areas that lack access to essential services and infrastructure. UN-Habitat estimates that close to a billion people currently live in these deprived and informal urban settlements, generally grouped under the term of urban slums. Two major knowledge gaps undermine the efforts to monitor progress towards the corresponding sustainable development goal (i.e., SDG 11—Sustainable Cities and Communities). First, the data available for cities worldwide is patchy and insufficient to differentiate between the diversity of urban areas with respect to their access to essential services and their specific infrastructure needs. Second, existing approaches used to map deprived areas (i.e., aggregated household data, Earth observation (EO), and community-driven data collection) are mostly siloed, and, individually, they often lack transferability and scalability and fail to include the opinions of different interest groups. In particular, EO-based-deprived area mapping approaches are mostly top-down, with very little attention given to ground information and interaction with urban communities and stakeholders. Existing top-down methods should be complemented with bottom-up approaches to produce routinely updated, accurate, and timely deprived area maps. In this review, we first assess the strengths and limitations of existing deprived area mapping methods. We then propose an Integrated Deprived Area Mapping System (IDeAMapS) framework that leverages the strengths of EO- and community-based approaches. The proposed framework offers a way forward to map deprived areas globally, routinely, and with maximum accuracy to support SDG 11 monitoring and the needs of different interest groups
Integrating openstreetmap data and sentinel-2 Imagery for classifying and monitoring informal settlements
Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science in Geospatial TechnologiesThe identification and monitoring of informal settlements in urban areas is an important
step in developing and implementing pro-poor urban policies. Understanding when,
where and who lives inside informal settlements is critical to efforts to improve their
resilience. This study aims at integrating OSM data and sentinel-2 imagery for
classifying and monitoring the growth of informal settlements methods to map informal
areas in Kampala (Uganda) and Dar es Salaam (Tanzania) and to monitor their growth
in Kampala. Three building feature characteristics of size, shape and Distance to nearest
Neighbour were derived and used to cluster and classify informal areas using Hotspot
Cluster analysis and ML approach on OSM buildings data. The resultant informal
regions in Kampala were used with Sentinel-2 image tiles to investigate the spatiotemporal
changes in informal areas using Convolutional Neural Networks (CNNs).
Results from Optimized Hot Spot Analysis and Random Forest Classification show that
Informal regions can be mapped based on building outline characteristics. An accuracy
of 90.3% was achieved when an optimally trained CNN was executed on a test set of
2019 satellite image tiles. Predictions of informality from new datasets for the years
2016 and 2017 provided promising results on combining different open source
geospatial datasets to identify, classify and monitor informal settlements
Mapping Informal Settlements in Developing Countries using Machine Learning and Low Resolution Multi-spectral Data
Informal settlements are home to the most socially and economically
vulnerable people on the planet. In order to deliver effective economic and
social aid, non-government organizations (NGOs), such as the United Nations
Children's Fund (UNICEF), require detailed maps of the locations of informal
settlements. However, data regarding informal and formal settlements is
primarily unavailable and if available is often incomplete. This is due, in
part, to the cost and complexity of gathering data on a large scale. To address
these challenges, we, in this work, provide three contributions. 1) A brand new
machine learning data-set, purposely developed for informal settlement
detection. 2) We show that it is possible to detect informal settlements using
freely available low-resolution (LR) data, in contrast to previous studies that
use very-high resolution (VHR) satellite and aerial imagery, something that is
cost-prohibitive for NGOs. 3) We demonstrate two effective classification
schemes on our curated data set, one that is cost-efficient for NGOs and
another that is cost-prohibitive for NGOs, but has additional utility. We
integrate these schemes into a semi-automated pipeline that converts either a
LR or VHR satellite image into a binary map that encodes the locations of
informal settlements.Comment: Published at the AAAI/ACM Conference on AI, ethics and society.
Extended results from our previous workshop: arXiv:1812.0081
Mapping New Informal Settlements using Machine Learning and Time Series Satellite Images: An Application in the Venezuelan Migration Crisis
Since 2014, nearly 2 million Venezuelans have fled to Colombia to escape an
economically devastated country during what is one of the largest humanitarian
crises in modern history. Non-government organizations and local government
units are faced with the challenge of identifying, assessing, and monitoring
rapidly growing migrant communities in order to provide urgent humanitarian
aid. However, with many of these displaced populations living in informal
settlements areas across the country, locating migrant settlements across large
territories can be a major challenge. To address this problem, we propose a
novel approach for rapidly and cost-effectively locating new and emerging
informal settlements using machine learning and publicly accessible Sentinel-2
time-series satellite imagery. We demonstrate the effectiveness of the approach
in identifying potential Venezuelan migrant settlements in Colombia that have
emerged between 2015 to 2020. Finally, we emphasize the importance of
post-classification verification and present a two-step validation approach
consisting of (1) remote validation using Google Earth and (2) on-the-ground
validation through the Premise App, a mobile crowdsourcing platform
Multi-level Feature Fusion-based CNN for Local Climate Zone Classification from Sentinel-2 Images: Benchmark Results on the So2Sat LCZ42 Dataset
As a unique classification scheme for urban forms and functions, the local
climate zone (LCZ) system provides essential general information for any
studies related to urban environments, especially on a large scale. Remote
sensing data-based classification approaches are the key to large-scale mapping
and monitoring of LCZs. The potential of deep learning-based approaches is not
yet fully explored, even though advanced convolutional neural networks (CNNs)
continue to push the frontiers for various computer vision tasks. One reason is
that published studies are based on different datasets, usually at a regional
scale, which makes it impossible to fairly and consistently compare the
potential of different CNNs for real-world scenarios. This study is based on
the big So2Sat LCZ42 benchmark dataset dedicated to LCZ classification. Using
this dataset, we studied a range of CNNs of varying sizes. In addition, we
proposed a CNN to classify LCZs from Sentinel-2 images, Sen2LCZ-Net. Using this
base network, we propose fusing multi-level features using the extended
Sen2LCZ-Net-MF. With this proposed simple network architecture and the highly
competitive benchmark dataset, we obtain results that are better than those
obtained by the state-of-the-art CNNs, while requiring less computation with
fewer layers and parameters. Large-scale LCZ classification examples of
completely unseen areas are presented, demonstrating the potential of our
proposed Sen2LCZ-Net-MF as well as the So2Sat LCZ42 dataset. We also
intensively investigated the influence of network depth and width and the
effectiveness of the design choices made for Sen2LCZ-Net-MF. Our work will
provide important baselines for future CNN-based algorithm developments for
both LCZ classification and other urban land cover land use classification
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