Surveyors, cartographers, photogrammetrists, and surveying and mapping technicians are responsible for measuring and mapping the Earth's surface. Surveyors establish official land, airspace, and water boundaries. They write descriptions of land for deeds, leases, and other legal documents; define airspace for airports; and take measurements of construction and mineral sites. Other surveyors provide data about the shape, contour, location, elevation, or dimension of land or land features. Cartographers and photogrammetrists collect, analyze, interpret, and map geographic information using data from surveys and photographs. Surveying and mapping technicians  assist  these professionals  by  collecting  data in

the   field,  making  calculations,   and  helping   with   computer-aided

drafting. Collectively, these occupations play key roles in the field of geospatial information.

Surveyors measure distances, directions, and angles between points on, above, and below the Earth's surface. In the field, they select known survey reference points and determine the precise location  of  important  features  in  the  survey  area  using specialized

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equipment. Surveyors also research legal records, look for evidence of previous boundaries, and analyze data to determine the location of boundary lines. They are sometimes called to provide expert testimony in court regarding their work or the work of other surveyors. Surveyors also record their results, verify the accuracy of data, and prepare plots, maps, and reports.

Some surveyors perform specialized functions that support the work of other surveyors, cartographers, and photogrammetrists. For example, geodetic surveyors use high-accuracy techniques, including satellite observations, to measure large areas of the earth's surface. Geophysical prospecting surveyors mark sites for subsurface exploration, usually to look for petroleum. Marine or hydrographic surveyors survey harbors, rivers, and other bodies of water to determine shorelines, the topography of the bottom, water depth, and other features.

Photogrammetrists and cartographers measure, map, and chart the Earth's surface. Their work involves everything from performing geographical research and compiling data to producing maps. They collect, analyze, and interpret both spatial data – such as latitude, longitude, elevation, and distance – and nonspatial data – such as population density, land-use patterns, annual precipitation levels, and demographic characteristics. Their maps may give both physical and social characteristics of the land. They prepare maps in either digital or graphic form, using information provided by geodetic surveys and remote sensing systems including aerial cameras, satellites, light-imaging detection and ranging (LIDAR), or other technologies.

LIDAR uses lasers attached to planes and other equipment to digitally map the topography of the Earth. It is often more accurate than traditional  surveying  methods  and  also  can  be  used to collect

other forms of data, such as the location and density of forests. Data developed by LIDAR can be used by surveyors, cartographers, and photogrammetrists to provide spatial information to specialists in geology, seismology, forestry, construction, and other fields.

Geographic Information Systems (GIS) have become an integral tool for surveyors, cartographers, photogrammetrists, and surveying and mapping technicians. Workers use GIS to assemble, integrate, analyze, and display  data  about location  in  a  digital  format. CIS

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typically are used to make maps which combine information useful for environmental studies, geology, engineering, planning, business marketing, and other disciplines. As more of these systems are developed, many mapping specialists are being called geographic information specialists.

Exercises