Surveyors, cartographers, and photogrammetrists 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 from surveys and from data and photographs collected using airplanes and satellites. 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 and elevations of points, lines, and contours 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 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 about their work. Surveyors also record their results, verify the accuracy of data, and prepare plots, maps, and reports.
Some surveyors perform specialized functions closer to those of cartographers and photogrammetrists than to those of traditional surveyors. 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.
Surveyors use the Global Positioning System (GPS) to locate reference points with a high degree of precision. To use this system, a surveyor places a satellite signal receiver—a small instrument mounted on a tripod—on a desired point, and another receiver on a point for which the geographic position is known. The receiver simultaneously collects information from several satellites to establish a precise position. The receiver also can be placed in a vehicle for tracing out road systems. Because receivers now come in different sizes and shapes, and because the cost of receivers has fallen, much more surveying work can be done with GPS. Surveyors then interpret and check the results produced by the new technology.
Field measurements are often taken by a survey party that gathers the information needed by the surveyor. A typical survey party consists of a party chief and one or more surveying technicians and helpers. The party chief, who may be either a surveyor or a senior surveying technician, leads day-to-day work activities. Surveying technicians assist the party chief by adjusting and operating surveying instruments, such as the total station, which measures and records angles and distances simultaneously. Surveying technicians or assistants position and hold the vertical rods, or targets, that the operator sights on to measure angles, distances, or elevations. They may hold measuring tapes if electronic distance-measuring equipment is not used. Surveying technicians compile notes, make sketches, and enter the data obtained from surveying instruments into computers either in the field or at the office. Survey parties also may include laborers or helpers who perform less-skilled duties, such as clearing brush from sight lines, driving stakes, or carrying equipment.
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—for example, 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, and LIDAR.
LIDAR—light-imaging detection and ranging—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, and construction, and other fields.
Geographic Information Systems (GIS) have become an integral tool for surveyors, cartographers and photogrammetrists, and surveying and mapping technicians. Workers use GIS to assemble, integrate, analyze, and display data about location in a digital format. They also use GIS to compile information from a variety of sources. GIS 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.
Work environment. Surveyors and surveying technicians usually work an 8-hour day, 5 days a week and may spend a lot of time outdoors. Sometimes, they work longer hours during the summer, when weather and light conditions are most suitable for fieldwork. Construction-related work may be limited during times of inclement weather.
Surveyors and technicians engage in active, sometimes strenuous, work. They often stand for long periods, walk considerable distances, and climb hills with heavy packs of instruments and other equipment. They also can be exposed to all types of weather. Traveling is sometimes part of the job, and land surveyors and technicians may commute long distances, stay away from home overnight, or temporarily relocate near a survey site. Surveyors also work indoors while planning surveys, searching court records for deed information, analyzing data, and preparing reports and maps.
Cartographers and photogrammetrists spend most of their time in offices using computers. However, certain jobs may require extensive field work to verify results and acquire data.
| 1. | Check all layers of maps in order to ensure accuracy, identifying and marking errors and making corrections. |
| 2. | Determine scales, line sizes, and colors to be used for hard copies of computerized maps, using plotters. |
| 3. | Monitor mapping work and the updating of maps in order to ensure accuracy, the inclusion of new and/or changed information, and compliance with rules and regulations. |
| 4. | Identify and compile database information in order to create maps in response to requests. |
| 5. | Produce and update overlay maps in order to show information boundaries, water locations, and topographic features on various base maps and at different scales. |
| 6. | Trace contours and topographic details in order to generate maps that denote specific land and property locations and geographic attributes. |
| 7. | Lay out and match aerial photographs in sequences in which they were taken, and identify any areas missing from photographs. |
| 8. | Compare topographical features and contour lines with images from aerial photographs, old maps, and other reference materials in order to verify the accuracy of their identification. |
| 9. | Compute and measure scaled distances between reference points in order to establish relative positions of adjoining prints and enable the creation of photographic mosaics. |
| 10. | Research resources such as survey maps and legal descriptions in order to verify property lines and to obtain information needed for mapping. |
| 11. | Form three-dimensional images of aerial photographs taken from different locations, using mathematical techniques and plotting instruments. |
| 12. | Enter GPS data, legal deeds, field notes, and land survey reports into GIS workstations so that information can be transformed into graphic land descriptions, such as maps and drawings. |
| 13. | Analyze aerial photographs in order to detect and interpret significant military, industrial, resource, or topographical data. |
| 14. | Redraw and correct maps, such as revising parcel maps to reflect tax code area changes, using information from official records and surveys. |
| 15. | Train staff members in duties such as tax mapping, the use of computerized mapping equipment, and the interpretation of source documents. |
| 16. | Research and combine existing property information in order to describe property boundaries in relation to adjacent properties, taking into account parcel splits, combinations, and land boundary adjustments. |
| 17. | Supervise and coordinate activities of workers engaged in plotting data and drafting maps; or in producing blueprints, photostats, and photographs. |
| 18. | Create survey description pages and historical records related to the mapping activities and specifications of section plats. |
| 19. | Calculate latitudes, longitudes, angles, areas, and other information for mapmaking, using survey field notes and reference tables. |
| 20. | Identify, research, and resolve anomalies in legal land descriptions, referring issues to title and survey experts as appropriate. |
| 21. | Complete detailed source and method notes detailing the location of routine and complex land parcels. |
| 22. | Answer questions and provide information to the public and to staff members regarding assessment maps, surveys, boundaries, easements, property ownership, roads, zoning, and similar matters. |
| 23. | Trim, align, and join prints in order to form photographic mosaics, maintaining scaled distances between reference points. |
| 24. | Produce representations of surface and mineral ownership layers, by interpreting legal survey plans. |
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