In recent years, Geographic Information Systems (GIS) have become indispensable for analysing contemporary urban growth. But, if the analytical and visualisation power of GIS is extended beyond the recent and future growth and integrated with the analogue information from the historic maps, it can also offer precise spatial-temporal analysis, offering a comprehensive understanding of urban evolution and morphology. This paper explores integrating GIS with urban morphological studies, demonstrating how GIS-based tools can reconstruct and analyse historical city growth patterns, especially where reliable cartographic sources are available. Such integration offers a powerful approach to understanding urban development, enabling precise insights into spatial changes over time.
This approach relies on the morphological data embedded in historic maps of different scales and provenances. Reconciling these data digitally and spatially requires a systematic and replicable methodology, and one that can cope with variations in morphological detail. Calcutta (modern-day Kolkata) which was the capital of British India (ca.1772-1911) has been chosen to demonstrate the viability of this integrated method, as the colonial governance generated abundant, multi-temporal maps, making Kolkata one among the few global metropolises whose origins are recent enough to be consistently traced and mapped.
Now, doing so also means tackling the familiar weaknesses of historic maps: geometric and projection errors, inconsistent symbols, colours, scales and conventions, print artefacts (e.g., press-induced distortions, ink bleed, plate wear, paper deterioration etc.), as well as imaging distortions introduced during photography or scanning. This method reframes these issues not as disqualifying defects but as recognised uncertainties requiring management. Specifically, this method employs controlled georeferencing with documented control points and RMSE thresholds, appropriate transformations such as spline or higher-order polynomials, depending on the condition of the original paper map. After georeferencing, standardised morphological features from each map (streets, plots and buildings) are digitised, making the relationship between the plan-elements computable and suitable for diachronic comparison among the various parts of the city, that are historically labelled “White Town” and “Black Town,” without reinscribing the categories uncritically. The simplicity and replicability of this method allow us to select other historical cities with similar cartographic evidence, and a synchronic comparison also becomes easier with the predetermined parameters of comparison (street density, street sinuosity, plots density, built coverage percentage etc.). It further helps us understand how spatial growth relates to social, political and cultural events. Methodologically, this offers a procedure that is neither normative nor purely subjective—a global, evidence-led, cognitive approach that any city, irrespective of its geographical and cultural context, can adopt. This is especially important for colonial cities like Calcutta, where the map sources are highly skewed to imperial interests.
Thus, this paper highlights the potential of using GIS based technologies as both computational engine and visualisation medium for historical urban analysis, at the same time assessing the limitations imposed by the source materials. The outcome is a transferable, auditable workflow that complements classic town-plan analysis and advances comparative, cumulative urban history in the digital humanities.
Diya Banerjee (Author/Presenter)
(AHRC-Northern Bridge Consortium Funded PhD Student)
School of Natural and Built Environment
Queen’s University Belfast
Primary Supervisor: Dr Keith Lilley