A widely useful purpose for performing a topographic survey involves the development of two-dimensional grids which reflect three-dimensional landscape elements. Both artificial and natural objects are examined and plotted by teams of geologists. Topographical depictions include hills, streams, bridges, buildings and trees. These illustrations are commonly referred to as relief maps.
Cartographic experts use lines, dots, colors and symbols to portray a variety of land features, including deep ocean depressions and high-altitude mountain peaks. Polygons, lines and points are the three primary symbols that are used on 3-D diagrams. Houses and other buildings are symbolized by dots. Linear features such as rivers, railways and roads are depicted by curved and straight lines. Wooded areas are usually shaded with greens, bodies of water with blues.
The spacing between the elevation lines delineate features such as deep trenches, steep hills and towering mountains. Widely spaced marks are used to portray gently sloping hillsides, while lines that are closer together indicate steep cliffs.
Scientists use a variety of methods to draft highly-detailed relief graphs. The direct inspection technique has been utilized since the development of the first 3-D chart in 1876 by team members from the U. S. Geological Service. Critical, informative data can be accurately collected by groups of on-site inspectors.
During the 1940s, cartographers expanded their data-collecting capacity with aerial photography. This advancement had an important impact on the accuracy and scope of global mapping.
The performance of a topographic survey can lead to the publication of accurate, accessible, meaningful information. Many people benefit from the opportunity to study the man-made and naturally-formed aspects of geographic locations without the need to travel to the sites in-person. Educators, builders, campers and others can interpret the data from 3-D maps to perform a diversity of functions, including engineering projects, weather analysis and family holiday planning.