The 1:10 million scale maps in Figure 33 show the same geographical area using the 1:110, 1:50 and 1:10 million Natural Earth data and the 1:2 million GADM data. It is important to choose data of the correct scale. The vector data provided by Natural Earth and DIVA are in the popular shape file format. DIVA-GIS provides global and country-level vector and raster data suitable for maps at a scale of 1:2 million (i.e. for which 1 cm on a scale bar represents 20 km). Natural Earth provides global vector and raster data designed for maps at scales of 1:10, 1:50 and 1:110 million i.e. maps for which 1 cm on a scale bar represents 100, 500 and 1,100 km, respectively. The Earth System Grid Federation climate predictions are available at several nodes.įigure 33: 1:10 million scale maps of northern Madagascar using the 1:110, 1:50, 1:10 million Natural Earth data and the 1:2 million GADM data. The 1:2 million data provided by DIVA is an earlier version of the data provided by GADM, so in most cases it is advisable to use the latter. Table 12: Sources of freely available base, ecological, environmental and satellite imagery map layers. The sections below describe and illustrate each in turn. Many of the most useful sources of map data are freely available (Table 12). The starting point for drafting a map is one or more base data layers-such as national or adminstrative boundaries, water bodies, roads or relief-for geographical context.
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