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 A topographic map ('topo') is a site map showing the topographic features of a site. Topographic features could include drainage patterns, locations of rock outcroppings, hills and other natural features. The map may also include artificial features such as buildings, utility locations, detention ponds and other features which would affect engineering design on the site. Topographic contours can be shown at almost any interval that is specified by the client. In areas of steep terrain, a larger contour interval can show the topography without the crowding of contour lines that would be introduced by a smaller contour interval. In areas of relatively flat terrain, a smaller contour interval is necessary to show the small changes in topography in a meaningful way.
The topographic map is prepared by gathering horizontal and vertical information in the form of XYZ coordinates. For smaller sites, the information may be gathered by traditional survey methods using a theodolite and data collector. For larger sites, it may be more cost-effective and produce better results to use aerial mapping methods. After the raw data has been gathered, it may be used to create a digital terrain model as an intermediate step to the production of contour lines.
A topographic map is often requested by engineers, architects or building contractors who need to know information about overall site grade and elevations. This information may be used to determine placement of site improvements, estimate the volume of dirt to be moved, or for many other construction and development purposes.
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