Page 1 of 2 Next  Ananya Ghosh Sub-Editor, GIS Development ananya.ghosh@gisdevelopment.net The history of surveying in Sri Lanka dates back to ancient times when sophisticated irrigation systems were laid down using excellent surveying techniques. The Greek geographer, Ptolemy, in his seminal work Geographia, drew the first outline map of Sri Lanka that was published around 150 AD. Ptolemy's depiction of the areal extent of Taprobane (Sri Lanka) was grossly over estimated owing to his limited knowledge of the world that lay outside the Greco-Roman world. Was Taprobane actually Sri Lanka? A definitive answer to this debatable question has not been found as yet. Many centuries later, artistic maps of Sri Lanka (then called Ceylon) were drawn by the Dutch imperialists in the 17th and 18th century using charts and more scientific cartographic techniques. The British were the ones who played an instrumental role in carrying out accurate surveys of the largest islands of the Bay of Bengal in the 19th century. Beginning of Modern Mapping The British published accurate maps of the island colony titled 'One inch to 4 miles map of Ceylon' for the first time in 1840. By 1897, the foundation for 'topographical mapping' was laid down after the survey for establishment of triginometrical stations for the Triangulation of Ceylon was completed. In 1924, a total of 72 maps, having a representative fraction of 1 inch to 1 mile was released. These maps not only depicted relief features but also contained cultural features, geographical names, administrative boundaries, contours etc. The 72 map series was drawn on the basis of plane table surveys. Within the next 25 years, old methods gave way to new ones after Sri Lanka gained independence from British rule in 1948. Aerial surveys for the whole of the island nation was conducted in 1956 on the scale of 1:40,000. The later part of the next decade witnessed the establishment of an Institute of Surveying and Mapping in the year 1969. Upgradation of Maps, Surveying and Mapping Methods The ready availability of trained surveyors and cartographers gave an impetus to the Land Use Mapping Programme, carried out between the years 1982-1991, wherein the entire country was surveyed at a district level on a scale of 1:100,000 using aerial photography and satellite imagery. The period from 1985 onwards saw a lot of activity in the field of mapping and surveying in Sri Lanka. The first edition of maps drawn on a metric scale of 1:50,000 was completed between 1985 and 1996 with the help of extensive ground and aerial surveys. These maps were essentially an updated version of the 1 inch: 1 miles series, albeit on a metric scale. In 1988, the first National Atlas of Sri lanka was published. By 1992, digital data compilation was introduced using photogrammetric techniques on aerial photographs. In 1994, a satellite image mosaic map of the country having a scale of 1:500,000 was published using IRS 1B LISS II imagery acquired from the National Remote Sensing Agency, India in 1992. ( see fig.1) Sri Lanka's expertise in remote sensing activities dates back to the late 1970s when the Center for Remote Sensing (CRS) was established under the Sri Lanka Survey Department. The Sri Lanka Center for Remote Sensing is the central organization for Remote Sensing related activities in the country. CRS is largely engaged in specific operations essential for interpreting remotely sensed data, specially interpretation of aerial photographs and satellite images. The main goal is to provide support and also supplement the existing mapping services in Sri Lanka that include land use mapping, national archiving of satellite data and satellite image mapping. The 1990s was a also decade of digitization of maps and surveys at large scales. Digitization of topographical maps were taken up. Also, the map series of scale 1:250,000 was completely digitized. By the end of the decade, the entire country of Sri Lanka was surveyed using aerial photography on a scale of 1:20,000. In the early 1990s, surveyors realised that the existing triangulation system in the country was not accurate enough to be used by systems like EDM (Electro-Magnetic Distance Measuring) and GPS (Global Positioning System). There was also a rising demand to establish a Land Information System that required precise geodetic control points. Thus, Sri Lanka's first highly accurate GPS device was procured in 1994. Using the GPS, triangulation surveys were conducted by measuring the distance between the base stations in order to establish precise control network. The longest line measured was from Jaffna to Matara with a distance of 417.26674 km having an accuracy of 3 cm. In 1999, the coordinates of all control points was published. This system came to be known as Sri Lanka Datum 1999.  Fig. 1: Satellite mosaic map of Sri Lanka (Source: Survey Department, Sri lanka) Present Status of Surveying and Mapping The current status of surveying and mapping looks extremely promising for the geospatial information community in Sri Lanka. Digital land use maps are being drawn at 1:50,000 scale using topographical maps of the same scale as the database. The second edition of National Atlas of Sri lanka is also in the pipeline. Sri Lanka is also one of the contributor countries to the Global Mapping Program organised by the International Steering Committee for Global Mapping. The global map data will have eight layers of database that include Elevation, Drainage, Land Cover, Vegetation, Land Use, Boundaries, Transportation and Population Centres. The establishment of digital topographic vector database on 1:250,000 and 1:50,000 scales has been completed, while the digitization of 1:10,000 database is still in progress. Once completed, the series will have 1834 maps. Fig.2 shows the current status of the digitization of 1:10,000 scale database. Map Products in Public Domain Topographical maps are available on three different scales, namely, 1:250,000 (available in English and Sinhala); 1:50,000 (available only in English) and 1:10,000 which are presently available for selected areas only. Administrative series maps having a scale of 1 inch to 1 mile, showing Electoral Districts, Administrative Areas and Local Authority Areas, are available only for limited areas. Historical map series is also available on sale which comprises Portuguese, Dutch and British period maps available for Galle Fort, Anuradhapura, Polonnaruwa and Colombo. Town maps of almost all the major towns and cities of Sri lanka are available to the general public.
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