Field
Methods:
Grids in area surveys
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| The
area survey is designed to uniformly sample a region by acquiring measurements
at a uniform spacing along X- and Y-axes in a regular cartesian
grid. The area to be surveyed is typically subdivided into a series of
square or rectangular grids in order that data from day-to-day and from
instrument-to-instrument can be efficiently managed and correctly located.
Grid sizes from 10 x 10 m to 30 x 30 m, or larger, are used. Within each
grid instruments are moved along traverse, and measurements are sampled
on each traverse according to a desired sampling density (see traverses
and samples in area surveys). Data collection with an instrument begins
in a grid and then commences to the next grid, and the next, and so on.
Grids are numbered for identification and may or may not be contiguous.
Work with several instruments can be ongoing within several grids simultaneously.
During data processing information from contiguous grids is tiled together
by software and all grids are correctly located spatially using software
like a geographical information system (GIS).
Because the grid controls the spatial positioning of the instruments, and therefore the accuracy of the mapping of identified anomalies, great care should be made in establishing the grid system using theodolites or EDM (see setting up a grid). Frequently, because of impediments on the landscape (buildings, trees and bushes, large rocks), only partial grids can be geophysically surveyed. |
Contribution
by: Kenneth
L. Kvamme, Archeo-Imaging Lab, University of Arkansas
