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Topographical mapping

Jul 2007 | Comments Off

	A historical perspective

Development of topographical maps in some countries

USA, Australia and China are chosen for case studies, being large countries.

USA

In 1807 President Jefferson established the ‘Survey of Coast’ that was renamed in 1836 as ‘US Coast Survey’ and 1878 ‘US Coast and Geodetic Survey’. This organization surveyed the area near the coast line till 1878. In the meantime the mapping of interior of county was done by several organizations including ‘Army Corps of Topographical Engineers’. First maps were generally drawn by hands. Different groups were working in uncoordinated way. Therefore US Geological Survey was established in 1879. USGS started with topographic survey on various scales from 1:24,000 to 1:250,000. But the object of complete coverage could not be achieved by target year of 1925.

Thereafter the National Topographical Program was introduced in 1939. This legislation laid down the specifications for the National Topographical Map Series and appropriate standards of map accuracy. Based on this programme 1:24,000 scale (except deserts), 1:62,500 scale (in Alaska 1:63,360) and 1:250,000 scale surveys were adopted. USGS began using aerial photographs to produce and update maps since 1930s.

By 1947 maps at the scale of 1:24,000/1:62,500 covered only 25% of USA but by 1968 this had been increased to 78%. In 1976, national coverage at 1:24,000 was 68% complete and about 80% of the Alaska (at 1:63,360) had been covered. By that time many countries including India had almost complete coverage on 1:50,000 scale.

In order to speed up the revision of existing map sheets, an interim revision was introduced in 1967. Extensive and important topographical changes were overprinted in purple on exiting maps by using aerial photography but without field check.. In 1975, it was decided that for all areas not yet covered by traditional 1:24,000 scale sheets, orthophotoquads (rectified photographs with important details, names grid/graticule and marginal items etc) should be produced especially for deserts and less developed areas.

As it became evident that complete coverage by traditional maps at 1:24,000 scale could not be achieved before the end of century, manuscript maps without cartographic fair drawing have been printed since 1982.

Based on the Metric Conversion Act of 1975 a modification of official topographic maps of the USA was made to confirm to the metric system. In the 1980s, the use of computer to scan, redraw and publish the maps significantly reduced the time required to update maps in areas of rapid growth. A new series on 1:100,000 scale was published which was compiled from 1:24,000 scale maps. Some states adopted 1:25,000 scale after adoption of metric system.

Now the complete country except Alaska is covered by more than 55,000 sheets produced on 1:24,000/1:25,000 scale and Alaska is covered by 2,700 sheets on 1:50,000 scale. In addition complete topographic coverage of USA is also available at 1:100,000 scale and 1:250,000 scale. Most of the data is now available in digital form. Maps or data can be obtained by anyone without any restriction. USGS provides topographical maps, orthophoto maps and aerial photographs in the entire USA online for nominal charges. This data is also available from various websites e.g. topozone.

There is demand for complete and up to date topographical information. For a country of the size of USA , it is huge task even with the latest technology. Therefore to meet this requirement, USGS has started ‘The National Maps Corps Volunteer Programme’. Any citizen having a GPS receiver can become the volunteer for a selected part of the country. He will provide GPS data and information about new details. After validating the information, the USGS staff will update the topographical database. Now USGS is expecting that the changes in topographical data will be captured and integrated with the existing data in a process of continuous update, rather than through cyclical revision of 10 to 20 years. They expect that currentness of the data will be measured in months and not in years and decades.

China

China also underestimated the efforts needed to produce the topographical maps and in 1903 they originally targeted to produce a map series at 1:25,000 scale. But this proved impossible due to the insufficiently advanced state of available technology and the enormous geographical extent of the country. In 1914 it was decided to generate mapping at 1:50,000 and 1:100,000 scale as an alternative. Preparation of these series was interrupted due to outbreak of World War I. Moreover sheets produced prior to that, were strongly criticized because of their general inaccuracy. In 1928 a revised programme was introduced by the newly created Central Bureau of Land Survey (CBLS). Triangulations commenced in 1930 and from 1932 photogrammetric techniques were used for topographical survey. Tremendous efforts were made but the progress suffered because of civil conflicts and the war between China and Japan. Till then, the scales employed were 1:25,000, 1:50,000, 1:100,000 and 1:2,50,000. When People’s Republic of China was established in 1949, a new survey of China was undertaken because original base materials were transported to Taiwan by the previous government. Approximately 8000 sheets of 1:50,000 series had been produced which covered about a third of the country. However these were of somewhat inconsistent quality.

In 1956 a new National Bureau of Surveying and Mapping (NBSM) was set up. This employed the Bejing coordinate system of 1954. The control work was finished by end of 1978. The sheetline, numbering methods and symbolization of topographic maps were standardized which were similar to former USSR. Following series were used.

1. 1:25,000 For large towns and industrial zones.
2. 1:50,000 For other populated areas
3. 1:100,000 For desert and high mountains.

The NBSM expanded & became fully operational in 1973. It implemented an extensive revision programme for medium scales. In 1982 three large Bureaus together with numerous provincial Bureaus were setup and passed to Ministry of Urban & Rural Construction and Environment Protection. At that time about 80,000 personal were involved in various aspects of mapping. Priority was given to the large-scale surveys which resulted in the production of sheets at 1:10,000 and also photomaps. Even larger scales had been adopted for major towns in certain cases. By 1990 approximately 1,65,000 sheets on large scales covering built up areas had been completed. It also finished the topographical mapping of the entire country on 1:50,000/1:100,000 scales.

China has adopted digital technology since 1990 for converting the maps in digital form. National Topographical Data Base on 1:50,000 scale was created in 2005. This task involved 10,000 people from 100 different organizations. It was coordinated by NBSM and was completed in eight years. Besides vector data, this dataset includes raster maps, imageries (including 1m resolution imageies for cities), terrain, landcover and meta-data.

Chinese topographical maps except general-purpose geographical maps and tourists maps are generally not available to general public. The government is providing geo-spatial data to the industry on need base.

Australia

In Australia topographic mapping was undertaken by Commonwealth and State government mapping organizations. In 1945 National Mapping Council was created by agreement between the Commonwealth and State governments. Its function was to co-ordinate Commonwealth and State mapping activities. In 1966, metric scales were introduced.

By 1967 the whole of Australia was covered by aerial photography for the first time. The medium scale contoured mapping covered a reasonable area. In year 1968, 1:250,000 scale planimetric map series was completed. Relief on this sereies was generally shown by spot heights and hill shading. However 20% sheets were contoured.

In 1967, compilation of 1:100,000 scale National Topographical Map Series (NTMS) commenced. Relief was generally depicted by 20 meter contours. It was published by Commonwealth Government with some assistance provided by the States. There are 3065 sheets in this series. Compilation of this series was completed by 1988. Initially the publication programme had been restricted to 1646 sheets along with the coastal margins of the continent and island state of Tasmania. The interior of the continent was compiled at 1:100,000 scale but published at 2,50,000 scale. This was completed by 1986.

In 1975 the publication of the 1:2,50,000 scale National Topographic Map Series commenced. Sheets in this series depict contours at 50 meters interval. The 1:2,50,000 scale NTMS is published to civilian specifications and a parallel 1:2,50,000 scale Joint Operations Graphic series is produced for defence requirements. All of the 541 sheets required at this scale were completed by 1989 in both the series.

Now topographic maps at scales of 1:50,000 and 1:25,000 are produced by Commonwealth and State government mapping organizations. Coverage at these scales is generally confined to the closer settled areas and other places of specific interest. The State mapping organizations also undertake mapping at scales of 1:10,000 and larger for cities and other fast developing areas.

Now Geoscience Australia is responsible for producing topographic map products with a national coverage. The NATMAP product brand refers to Geoscience Australia’s new 1:100,000 and 1:2,50,000 scale paper map products. The GEODATA product brand refers to its structured digital GIS and mapping data product at scales between 1:2,50,000 and 1:1 million. Now 1:2,50,000 is the largest scale at which National Digital Topographic Data Base exists for entire continent. It is available in different themes and contains a number of feature classes. Large-scale digital data is available for developed areas. Most of the digital products are priced and are licensed for use and available to users without any further restriction.

Conclusion

Topographical mapping evolved as one of the tools of colonial powers to serve their interest. Afterwards it became essential for armed forces for planning and execution of their operations. This brought the attribute of ‘secrecy’ attached to it during 18th, 19th and early 20th century.

Applications of topographical maps for developmental activities had started gaining importance from last century. Independent experts calculated that around 10% of Great Britain’s economic activity is dependent on Ordnance Survey ( NMA) data. It is about 136 billion pounds worth of economic activity in Britain.

With the advent of GPS, total stations, digital photogrammetry, digital cartography etc. all the stages of map making have become automatic, very easy, flexible and fast. Now the demands of user community is also changing. They want multilayered, current, complete, consistent and accurate data on larger scale, tailored for their use. Therefore concept of National Spatial Data Infrastructure is being developed in many countries.