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Urban Expansion in Spitali: A Satellite-Based Analysis (2015–2025)
Cyprus is undergoing a rapid expansion in population, primarily due to geopolitical issues in Eastern Europe and the Middle East. Much of this growth has been centred around the town of Limassol, which has grown by between 8% and 10% since 2020.
Associated with this has been a building boom. The village of Spitali, which lies at the northern tip of the Limassol conurbation, has seen extensive expansion of its housing network. To quantify this growth, I used historical satellite imagery together with a CNN-based neural network model (previously trained on buildings elsewhere in Cyprus) to estimate changes in the landscape for the Spitali village environs, specifically detecting the extent of buildings.
The area sampled was approximately 1.5 km by 1 km. Each image patch analysed represented an area of around 150 × 150 square metres. Random sampling indicated that the model achieved an overall accuracy of 93%, with an F-score of 0.89 when applied to the Spitali datasets. This represents strong performance given the training data and application domain.
Two datasets were used: one generated from January 2015 and another ten years later, from June 2025 (the most recent available). The results showed that in 2015 there were 51 image patches that included buildings. By 2025, this had increased to 66, representing a 29% increase. Building has continued apace since the latest high-resolution satellite images became available. I intend to collect updated images as they become available and rerun the models to monitor the rate of change.
Model comparison using McNemar's Test.
Can now compare model performanace using McNemar's Test. McNemar’s test is a statistical test used to compare two classification models on the same dataset by evaluating whether their error rates differ significantly. This can now be used to evaluate whether one model is better than another. The screenshot below shows the results of comparing the ResNet50 architecture against MobileNetV3, with ResNet50 winning out on this dataset.
Graph Neural Networks
Prototyped some graph neural networks, with a ResNet50 backbone, using pytorch. Graph neural networks model data as nodes and edges to learn from relationships and structure rather than isolated features. In image classification, they represent pixels, regions, or objects as graphs, enabling context-aware recognition that captures spatial and semantic relationships beyond standard CNNs. Promise shown; on the garbage detection domain it exhibited similar performance to that of basic ResNet50.
Model comparison using McNemar's Test.
Can now compare model performanace using McNemar's Test. McNemar’s test is a statistical test used to compare two classification models on the same dataset by evaluating whether their error rates differ significantly. This can now be used to evaluate whether one model is better than another. The screenshot below shows the results of comparing the ResNet50 architecture against MobileNetV3, with ResNet50 winning out on this dataset.