6.9 Map Data

6.9 Map Data

In remote sensing, the following maps are needed for particular objectives. Given below are requirements for satellite remote sensing. For airborne sensing one usually requires the larger scaled maps.

a. Topographic map:
1.25,000 or 1/50,000 topographic map will be best used to select ground control points and to extract DEM (digital elevation model) for digital rectification or the generation of a three dimensional view.

b. Thematic maps;
Land use, forest, soil, and geological maps etc. are used to collect training data for classification. A map scale of 1/50,000 - 1/250,000 is best for this purpose. The thematic maps can be digitized to permit integration of remote sensing data into geographic information systems (GIS) containing the thematic information.

c. Socio-economic maps;
Political units, transportation network, population distribution, agricultural and industrial census, tax or land price, and so on, are important factors for remote sensing applications and GIS.

Table 6.9.1 summarizes the required maps for remote sensing and GIS. Global change monitoring with the use of NOAA AVHRR, Nimbus CZCS or geosynchronous meteorological satellites is important for earth environmental analysis. In such cases, world maps which cover the whole earth may be necessary as a reference. Up to now, United Nations organizations such as UNESCO, UNEP, UNFAO etc. as well as NASA, NOAA and other international organizations, have produced various world maps.

Table 6.9.2 shows the UN statistics for world topographic mapping as of 1987 with respect to the map scale and region. As seen in this table, topographic maps of 1:50,000 scale have been completed for only about 60 % of the total earth's land area, with especially low coverage in Africa, South America and Oceania. This is one reason why high resolution stereo image data are required for topographic mapping from space, and why radar imagery is attractive.