A topographic survey is usually performed by a group of geologists with the goal of producing two-dimensional maps which represent three-dimensional components of the landscape. The features commonly included are both natural and man-made objects, such as mountains, lakes, trees, dams, buildings and roads. These diagrams are also known as relief maps.
The cartographers use contour lines, symbols and colors as representations for different land elements, including elevation and depressions. The line, polygon and point are the three main symbols incorporated into topographical diagrams. Small structures such as buildings are represented by dots. Straight, curved and dotted lines are used to depict linear items such as roads, railways and rivers. Wide expanses of water are often indicated by blues, dense forests with greens.
Contoured lines spaced apart at specific intervals can be utilized to illustrate sharp slopes, deep trenches and tall mountains. The more closely spaced lines symbolize steep hills, while widely spaced lines denote gentle slopes.
There are several methods used during the creation of relief diagrams. The direct inspection of a site has been a consistent practice since the earliest known topographical map was created by the United States Geological Service in 1876. Visiting sites can provide the map-making teams with important confirmable data points.
Since the 1940s, aerial studies have also provided valuable resources to cartographic teams. The development of the ability to take photographs from airplanes and helicopters has helped expand the detail and accuracy of relief charts.
An effective topographic survey can lead to the creation of very useful pamphlets. Campers, engineers, hikers, students and others can have the advantage of exploring the natural and artificial land features of areas without being required to visit the sites in person. Among other uses, access to landscape details can be helpful when planning vacations, analyzing weather patterns or considering construction projects.