Survey.
Archaeological survey may comprise of a range of survey techniques, from topographic, contour and 3D surveys of visible earthworks, to geophysical survey of buried archaeological remains. Surveys may be required as a planning condition prior to visible archaeological remains being affected by development, whilst geophysical techniques may be used as part of an evaluation programme of works, or to target trial evaluation trenches prior to development.
Geophysics
This is the way in which people attempt to find underground features by using various, usually, electrical devices. The principal techniques used are magnetometry, resistivity, magnetic susceptibility, ground penetrating radar, electromagnetic techniques, metal detectors, seismic methods, sonar and micro gravity.
Geographic Information System (GIS)
A Geographic Information System (GIS) is software that blends the power of a map with the power of a database to allow people to create, manage and analyse information, particularly information about location.
GPS Survey.
GPS stands for global positioning system, is a satellite-based navigation system. GPS was first developed for military use starting in the 1970s and became fully operational in 1993. Since then, it has expanded its use to consumer and commercial applications.
GPS uses a network of satellites, which communicate with receivers on the ground. When a receiver requests data to calculate its location, four or more GPS satellites will communicate with the receiver, sending the position of the satellite, the time the data was transmitted and the distance between the satellite and the receiver. The information collected from these satellites then calculates the latitude, longitude and height of the receiver. If the receiver is moving, continuous data collection can be used to calculate the changing position of the receiver over time, which can be used to calculate speed. No matter the weather conditions or time, GPS can triangulate the signal and provide a location.
GPS technology provides valuable information for surveyors to help develop plans and models for client projects.
3D Photogrammetry.
Photogrammetry is the use of a two-dimensional (2D) image or images, such as a photograph, to allow a person to analyze the image in order to make accurate measurements of size and orientation of the objects in the image in terms of the original three-dimensional (3D) space. The process allows a person to make measurements of the height, width, and depth of objects in a photograph or similar 2D image, which can then be used to re-create the objects to scale in 3D space. With 3D photogrammetry, the application is used to take images of objects, such as photographs, and re-create the original object as a 3D computer model, typically for use in computer animation or similar applications.
LiDAR
LiDAR is an acronym of “light detection and ranging” is a method for determining ranges (variable distance) by targeting an object with a laser and measuring the time for the reflected light to return to the receiver. LiDAR can also be used to make digital 3-D representations of areas on the earth’s surface and ocean bottom, due to differences in laser return times, and by varying laser wavelengths. It has terrestrial, airborne, and mobile applications.
The technique is commonly used to make high-resolution maps, with applications in surveying, geomatics, archaeology, geography and geology.
