![]() ![]() Local governments (state, county, municipality) may have additional higher-quality data that is not available from The National Map, and these can included LiDAR-derived DEMs, more detailed contours, or other forms of data. ![]() For larger areas, a number of approaches can work, including contours available from The National Map at the 1:1million scale (see the Small-scale Datasets section). For smaller areas, try downloading raster data at the 1/3 or 1/9 arc-second, and deriving your own contours. More than 100 such sheets have been produced. A topographic map is a detailed and accurate graphic representation of cultural and natural features on the ground. From 1958, a number of town maps at scales of 1:5,000 or 1:10,000 were also made, initially on the Gauss-Krger projection, but after 1970 on a stereographic projection. ![]() Contours at this scale will not be detailed enough for small areas, like a city block, and will have too much detail for representing topography over larger areas. These products are available in print, digital raster and digital vector GIS formats from East View Geospatial. This is suitable for mapping at somewhere around the size of a neighborhood or town. Next, the vector contours must be tagged with their corresponding elevation values. Topographical Map Content Owned & Maintained by Survey of India Feedback. Data for Alaska is at a different resolution.Ĭontours are available at a scale of 1:24000. The raster elevation contours must first be converted to vectors. Some areas have higher resolution data, at 1/9 arc-second (1 point every 3 meters), including SE Michigan. Raster resolution is 1 arc-second (approximatelly 1 point every 30 meters) and 1/3 arc-second (approximately 1 point every 10 meters) for most areas. 3DEP data from the USGS (which has superceded the National Elevation Dataset (NED) USGS is a primary source of geographic information system (GIS) data. ![]()
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