Abstract:
A map can be defined as a scaled graphic representation of the Earth’s surface. People have
been using maps since the earliest civilizations. Initially, these historical maps were
considered only as objects with historical value. However, with the development of
Geographic Information System (GIS), new methods emerged to digitize these old paper
maps using Georeferencing and overlaying them on various modern maps, such as satellite
image platforms. Although the earliest map representation of Sri Lanka dates back to 139 AD,
European colonials compiled detailed maps of the island. Under Dutch rule along the coastal
areas of Sri Lanka, many maps of their fortifications were produced, with one of the most
significant being the Colombo fortification. Originally constructed by the Portuguese and later
developed and reconstructed by the Dutch, this monument is not visible today except for a
few remnants. The Dutch compiled numerous plans and maps of the Colombo fortification;
some are available for download in the Dutch archive in the Netherlands. Against this
backdrop, the objective of this research was to georeference one of these historical Dutch
maps, overlay it on a present-day Google map, and compare the past and present landscapes
of the Colombo Fort area. Following the Georeferencing process, the historical map achieved
a remarkably accurate overlay on the satellite map, with a Root-mean-square (RMS) error of
approximately 7 pixels. The output provides a clear understanding of the Dutch fortification's
function during the 17th century and the locations of its components in the present space of
Colombo. Importantly, it underscores that while the fortress may be invisible today, the
spatial arrangement of the current Colombo Fort remains akin to its Dutch predecessor.
